Conference PaperPDF Available

Pathology of Macropods

Ladds, P.W., and I.K. Barker. Pathology of Macropods. In: K. Rose (ed), Proceedings,
Diagnostic Pathology of the Diseases of Aquatic, Aerial and Terrestrial Wildlife 2012,
Australian Registry of Wildlife Health, Sydney, NSW, Australia. February 13-18, 2012,
pp. 254-
Philip W. Ladds
Graduate Research College, Southern Cross University
P.O. Box 157, Lismore, NSW 2480
Revised by
Ian K. Barker
Canadian Cooperative Wildlife Health Centre, Ontario/Nunavut Region
Dept. of Pathobiology, Ontario Veterinary College,
University of Guelph, Guelph, ON, Canada N1G 2W1
Most information in these notes is covered more fully in ‘Pathology of Australian Native Wildlife’ (Ladds,
2009), in which references to cited literature, other than those added in revision, are given.
Readers are referred to the publications below for information on the systematics, biology, anatomy,
physiology, captive management and medicine of macropods, which may aid in interpretation of disease
processes encountered by the pathologist.
Armati, P.J., C.R. Dickman & I.D. Hume (eds). 2006. Marsupials. Cambridge University Press,
Cambridge. Pp 373.
Coulsen, G. & M. Eldridge (eds). 2010. Macropods. The Biology of Kangaroos, Wallabies and Rat-
kangaroos. CSIRO Publishing, Collingwood. Pp 408.
Jackson, S. 2003. Australian Mammals. Biology and Captive Management. CSIRO Publishing,
Collingwood. Pp 524.
Ladds, P. 2009. Pathology of Australian Native Wildlife. CSIRO Publishing, Collingwood. Pp 640.
Tyndale-Biscoe, H. 2005. Life of Marsupials. CSIRO Publishing, Collingwood. Pp 464.
Vogelnest, L., & R. Woods. 2008. Medicine of Australian Mammals. CSIRO Publishing,
Collingwood. Pp 686.
Alphaherpesviruses (Macropod Herpesvirus-1 and -2) have been associated with disease in a number
of macropod species, virtually always in captive animals, although there is serologic evidence of wide
exposure to herpesviruses in free-ranging macropods. These agents are capable of latency, have been
detected in the trigeminal ganglion, and may recrudesce in immunocompromised animals.
In general, clinical signs include respiratory rales, conjunctivitis, discharge from the eyes and nostril,
incoordination, vesicles 2 to 3 mm in diameter in the labial and gingival mucosa and ano-genital region,
depression, anorexia, and death.
Gross lesions can include the mucocutaneous vesicles and ulcers seen clinically; pulmonary congestion
and edema; pinpoint red foci in the lungs; and pale 1-5mm diameter foci scattered throughout the liver. In
parma wallabies a mucoid tracheitis was observed.
Microscopic changes included lymphoid depletion and apparent lymphocytolysis in germinal centres in
the spleen, and multifocal necrosis in the liver. Eosinophilic to basophilic intranuclear inclusions are
scattered in hepatocytes around necrotic foci. In experimental infections in parma wallabies, inclusions
were not seen in liver, but necrosis with mineralisation was a feature.
Gammaherpesvirus infection (Macropod Herpesvirus-3) recently has been reported in a captive
collection of eastern grey kangaroos in North America and in a free-ranging animal in Victoria. In the
captive collection the virus was detected in a population with a high prevalence of mammary tumours, in
individuals with clinical ulcerative cloacitis. The Victorian case was from a population, including animals
relocated subsequent to the bushfires of 2009, in which a small outbreak of mortality was noted, though
none were necropsied. Animals were observed with ataxia, oculo-nasal discharge, lethargy and
recumbency. Mucosal lesions were not noted in the single animal examined clinically. However, a
gammaherpesvirus similar to that described in the captive animals was detected by PCR on swabs, but
not isolated. While the association of a gammaherpesvirus with clinical disease in these cases is not
proof of causality, it indicates that it should be suspected in grey kangaroos with ulcerative
mucocutaneous lesions and/or respiratory disease.
Diagnosis of herpesviruses is suggested by the pattern of gross and microscopic lesions and confirmed
by virus isolation, PCR, or presumptively, by electron microscopy on tissue sections.
Wilcox, R.S., P. Vaz, N.P. Ficorilli et al. 2011. Gammaherpesvirus infection in a free-ranging
eastern grey kangaroo (Macropus giganteus). Australian Veterinary Journal 89: 55-57.
Enlarged epithelial cells containing prominent eosinophilic intranuclear inclusions have been described as
an incidental finding in the renal collecting tubules of Eastern Bettongs. The agent involved has not been
confirmed, but ultrastructurally, it is consistent with an adenovirus, rather than a herpesvirus, since no
enveloped particles were observed in the cytoplasm of affected cells.
Poxvirus and papillomavirus
The lesions caused by these viruses represent separate disease entities. However, some reports of
clinically similar proliferative skin lesions in macropods and several other native Australian species are
Papillomaviruses associated with typical warts have been described among marsupials only in
brushtailed possums and woylies, although papillomavirus genome has been detected on the skin of
clinically normal koalas and from an eastern grey kangaroo, among the seven macropods surveyed. The
lesions on the woylie were comprised of multiple projecting papillary folds, with marked orthokeratotic
and parakeratotic hyperkeratosis. The thick stratum spinosum contained typical koilocytes, and
immunohistochemistry and in situ hybridization revealed papillomavirus signal in nuclei, although
intranuclear inclusions were not described.
Lesions compatible with poxvirus infection in the skin of macropods (quokka, tammar wallabies, agile
wallabies, swamp wallabies, wallaroos, red kangaroos, eastern and western grey kangaroos), are
described in all ages, but mostly young animals. They may be solitary or multiple, and occur in skin on
any part of the body, such as the tail, head or limbs. Two types of lesion, varying from a few mm to about
5 cm in diameter, are described. Whether these lesion types are distinctly different or whether there is a
single entity, which in some animals may produce multiple lesions resembling human molluscum
contagiosum, is unresolved. This latter type, seen infrequently, is an umbilicated, firm to hard papule that
is non-tender. More common are proliferative, wart-like lesions that are irregular, have a roughened,
hyperkeratotic surface, and become hairless and darker as they enlarge.
The microscopic appearance depends on the type of lesion and stage of development or regression. In
those resembling molluscum contagiosum, hyperkeratosis and accumulation of trapped keratin in deeper
locations may give the lesion a cup-shaped appearance at low magnification. In the papillomatous lesion
there is marked acanthosis and hyperkeratosis, the thickened epidermis being directly continuous with
normal epidermis. The more superficial cells are enlarged, often vacuolated, and may contain
intracytoplasmic, eosinophilic inclusions up to approximately 45 µm in diameter which displace the
nucleus. The amount of dermal inflammation associated with these lesions varies. There may be
necrosis of the superficial part of the lesion, with a marked local neutrophilic infiltrate, and a
lymphoplasmacytic infiltrate may be evident in the dermal papillae and subjacent dermis. While typical
poxviruses have been demonstrated using electron microscopy, neither isolation nor molecular
characterisation seems to have been accomplished.
Bennett, M.D., A. Reiss, H. Stevens et al. 2010. The first complete papillomavirus genome
characterised from a marsupial host: a novel isolate from Bettongia penicillata. Journal of
Virology 84: 5448–5453.
Serology and virus isolation have confirmed that infections with arthropod-borne viruses are common in
native mammals in Australia, but with the exception of Wallal, and perhaps Warrego and Eubenagee
viruses, although infection and viraemia in native species may amplify the viruses, they are not
associated with overt illness or demonstrable lesions.
Two significant systemic diseases of macropods caused by orbivirus infections are recognised, epidemic
blindness (choroid blindness, chorioretinitis of kangaroos), and a sudden death syndrome in tammar
Epidemic blindness: Blindness, associated with infection by a midge-transmitted orbivirus of the Wallal
serogroup, and possibly Warrego virus, has been observed in western grey kangaroos, and less often in
eastern greys, red kangaroos and euros.
Gross lesions directly attributable to the viral infection are not reported.
Microscopically, in both spontaneous and experimental cases there is chorioretinitis with uveitis and often
an accompanying non-suppurative encephalitis or meningoencephalitis. In some animals, however, there
is encephalitis with no ocular lesions. In acute lesions chorioretinitis is severe and necrotising, with
proteinaceous exudate, and neutrophils and gitter cells in the reaction. It may be segmental, or so
extensive that little normal retinal tissue remains. In older lesions, chronic retinitis may be associated with
segmental retinal atrophy, perhaps with little inflammation, and Wallerian degeneration of the optic nerve
and optic tracts in the brain. Significant changes are not evident in other (non-ocular) tissues.
Sudden death syndrome in tammar wallabies: Sudden deaths associated with an orbivirus of the
Eubenangee serogroup have been described in captive tammar wallabies. Mortality rates can be high,
and most animals died without showing signs.
Grossly, consistent findings included pulmonary congestion, subcutaneous oedema of the hindlimbs and
inguinal region, and mottling of the liver. Additionally, in about 30% of animals, there was extensive
haemorrhage in many areas including fascia and muscle of the hindlimbs, the inguinal and dorsal cervical
regions, ventral thorax and perirenal area.
Microscopically, congestion and haemorrhage, especially in the liver, were confirmed and in some there
was acute periacinar hepatic necrosis. The gross and microscopic findings are consistent with endothelial
damage and disseminated intravascular coagulation, pathogenetic mechanisms common to orbiviral
diseases such as Bluetongue and Epizootic haemorrhagic disease.
Rose, K.A., P.D. Kirkland, R.J. Davis et al. 2012. Epizootics of sudden death in tammar wallabies
(Macropus eugenii) associated with an orbivirus infection. Australian Veterinary Journal. In press.
Encephalomyocarditis virus
Encephalomyocarditis (EMC) virus, a picornavirus, has been identified by immunohistochemistry in the
myocardium of a quokka, and was also diagnosed or suspected as the cause of myocarditis and death in
captive macropods.
Gross findings appear to be similar regardless of species, and include focal or diffuse pallor of the
myocardium, perhaps mostly of the ventricles, and pulmonary congestion.
Microscopically, necrotising non-suppurative myocarditis is a consistent lesion, with accompanying
fibrosis in some, presumably more chronic, cases.
Other viruses
Foot and mouth disease (FMD) virus: Following experimental infection with the FMD virus, lesions –
consisting of vesicles on the tongue and foot pads – were noted in red kangaroos and (Matschiei’s) tree
kangaroos (Dendrolagus matschiei). It was concluded unlikely that these species would play a significant
role in the spread of FMD.
A recent report, however, described FMD in an eastern grey kangaroo captive in a zoological garden in
India. Signs were those of sloughing of footpads, pain sufficient to prevent the animal from standing, and
death two days after the onset of signs. Microscopically, focal myocardial necrosis and myocarditis were
observed. Culture and typing by ELISA confirmed the presence of type O FMD virus.
Pathological changes observed in animals with bacterial infections, especially acute infections, are chiefly
those of septicaemia, are seldom specific, and probably for this reason are rarely reported. Fortunately,
as is the case with most injurious agents, in sub-acute and chronic disease with persistent infection or
exposure, host response usually becomes increasingly obvious, and the type of response may be highly
specific or even pathognomonic.
(a) Gram-positive bacteria
Included here are infections with Staphylococcus aureus, S. epidermidius, S. xylosus and S. capitis.
Whereas S. aureus often appears to be a primary pathogen the other staphylococci are normally non-
pathogenic or opportunistic.
Although most Australian native terrestrial mammals are susceptible to staphylococcal infection, some
species differences have been noted; macropod joeys seem to have innate resistance to S. aureus
Gross findings may be those of peracute septicaemia with widespread petechial haemorrhage.
Localising lesions vary with the duration of infection – acute lesions being fluctuating, and oedematous or
suppurative, with later lesions being firmer due to abscess formation and fibrosis, and sometimes
granuloma formation (botryomycosis).
Microscopic findings may be confounded by concurrent infection with other bacteria, especially if the
lesion is superficial or cutaneous. Although the inflammatory response in staphylococcal infections seems
mostly to be exudative and suppurative, the presence in some cases of so-called ‘club colonies’
surrounded by a pyogranulomatous response gives the lesion some specificity which is helpful in
diagnosis of the botryomycotic form of staphylococcosis. This change has been observed in the koala,
bilby, and echidna, and may presumably occur in macropods.
Diagnosis at necropsy is based on culture of localising lesions, or of several parenchymatous organs
(liver, spleen, lung) in the case of suspected septicaemia. Histologically staphylococci are recognised as
large Gram (+) cocci, sometimes forming clusters.
Most reports of disease in Australian native land mammals associated with streptococcal infection
incriminate β-haemolyic streptococci but in some reports no species identification is given.
Infection with both haemolytic and non-haemolytic streptococci occurs frequently and may be secondary
to, or concurrent with, other microbial infections such as in candidiasis in young hand-reared kangaroos,
or with Fusobacterium necrophorum and other bacteria in ‘lumpy jaw’ necrobacillosis. In such cases the
precise contribution of streptococci to illness cannot be assessed. Infection of wounds is commonly due
to β-haemolytic streptococci as well as other bacteria such as Staphylococcus aureus and
Corynebacterium spp. On the feet and lower limbs these may be evident as suppurative pododermatitis
with tenosynovitis, and purulent to caseous inflammation and necrosis of the draining lymph nodes.
Streptococcus equisimilis, usually a human pathogen, was isolated from a fatal osteomyelitis lesion mid-
shaft in the radius and ulna of a mature eastern grey kangaroo. Necropsy revealed a small sinus filled
with creamy yellow pus.
Diagnosis is based on culture of localising or suspected primary lesions, or of parenchymatous organs in
suspected speticaemias. Streptococci can be recognised in tissue as small Gram (+) cocci, often
arranged in pairs or sometimes small clusters.
Arcanobacterium pyogenes is a pyogenic, Gram (+), pleomorphic, cocco-bacillary organism that can
cause a wide variety of nonspecific suppurative lesions involving various visceral organs. As with
staphylococci and streptococci, Arcanobacterium pyogenes frequently is isolated from inflamed lesions
due to trauma sustained in capture of wallabies and several other native mammals. Footpads are
especially involved with resultant suppurative pododermatitis, tenosynovitis and lymphadenitis. In
untreated animals, septicaemia and embolic pneumonia may follow.
Tetanus, resulting from infection of wounds with Clostridium tetani, is described as common in
marsupials but opinion on its significance in these species is divided. It is reported in several macropod
species. Signs, which may be of sudden onset and rapid progression, include protrusion of the nictitating
membrane, dilation of nostrils, and marked tetanic contraction of muscles, especially those of the head,
neck, thorax, forelimbs and tail. Mastication becomes ‘impossible’, presumably due in large measure to
so-called ‘lock jaw’, and pulmonary oedema – as evidenced by frothing at the nostrils and dyspnoea –
develops, and death occurs within several days.
Because pathological changes in tetanus are minimal, diagnosis must be based on clinical signs. Tearing
of muscles associated with severe terminal spasms has however been observed, and lesions providing
anaerobic conditions conducive to germination of C. tetani, may also be found. Such lesions have
included a dog bite, and compound fractures of metatarsal bones.
Enterotoxaemia is reported in young kangaroos. Necropsy revealed petechiation on serous surfaces,
and much translucent, straw-coloured fluid in body cavities. Within the small intestine there were
petechiae and much ‘custard-like’ ingesta, a smear of which, when examined after staining with
polychrome methylene blue, was seen to contain moderate numbers of bacterial rods consistent with
Clostridium perfringens.
Tyzzer’s Disease, caused by Clostridium piliforme, has been reported in diverse native mammals
including an eastern grey kangaroo, and a male wallaby of unrecorded species. Most reported cases of
Tyzzer’s disease involved captive juveniles in which disease appeared suddenly and progressed quickly,
with death occurring in one to several days.
Gross findings were chiefly observed in the liver, which was enlarged, congested and mottled, perhaps
with an accentuated lobular pattern and scattered haemorrhages, and multiple pale, grey-white foci up to
3 mm in diameter throughout the parenchyma. Unlike in other diseases producing focal hepatic necrosis,
including herpsviruses, and Gram-negative septicemias, in which there is splenic enlargement or focal
necrosis, in Tyzzer’s disease, the spleen is normal or perhaps shrunken. Typhlocolitis, often seen in
eutherian mammals with Tyzzer’s disease, seems not to have been reported in macropods.
Histologically, in the liver the significant change in all cases was multifocal necrosis. The causal bacilli
were usually discernible at the edge of lesions as faintly basophilic rods in sections stained with
Haematoxylin and Eosin. They do not take Gram stain, but with silver (GMS) staining were seen clearly
as skeins of distinct, often beaded rods.
Perhaps because clinical signs and pathological findings of Erysipelothrix sp. infection in native fauna
lack specificity, erysipelas in these species seems under-reported. There is an early report of E.
rhusiopathiae causing ‘raised red’ lesions on the inner aspect of the hindlimb of two kangaroos, and
erysipelas has also been diagnosed in a captive wallaby with septicaemia manifested by muco-
haemorrhagic enteritis, epicardial petechiation and splenomegaly.
Microscopically, E. rhusiopathiae is distinguished as one of the only two Gram (+) coccobacilli likely to be
encountered in tissue (the other is Listeria). Microcolonies may be found in capillaries and small venules
throughout the body, associated with microvascular thrombosis, which probably explains the
haemorrhage which often is evident grossly in some tissues, such as epicardium. E. rhusiopathiae is
zoonotic, usually causing localised digital cellulitis, termed ‘erysipeloid’, and, rarely, valvular myocarditis or
septicaemia. Confusingly, ‘erysipelas’ in people is a dermal cellulitis caused by Streptococcus.
Actinomyces and Nocardia
These organisms are difficult to culture, and may occur in mixed infections with Fusobacterium.
Diagnosis often is based on their appearance in tissue sections, where both produce pyogranulomatous
inflammation. Actinomyces appears filamentous, and unequivocally Gram (+), while Nocardia is variably
Gram (+), forming beaded filaments, and stains weakly acid fast by a modified Ziehl-Neelsen method.
Both are environmental organisms which may be ingested or found in the mouth. They cause
opportunistic infections, often gaining entry to deeper tissues via a breach in the skin or oral mucosa,
where especially Actinomyces may be found in lesions of ‘lumpy jaw’. Actinomycosis, apparently
unassociated with jaw lesions, was diagnosed as the cause of abdominal abscesses in a captive
Nocardiosis in macropods appears especially to involve the lungs, perhaps through inhalation of
contaminated material, with acute respiratory embarrassment being observed clinically. Necropsy may
reveal pyogranulomas, multi-focal caseous abscessation or involvement of an entire lobe, with adhesions
between lobes, and serosanguinous exudate in the pleural cavity. Microscopy reveals the typical
appearance of the organism.
Listeriosis due to infection with Listeria monocytogenes has been diagnosed in a red-necked wallaby and
a rufous bettong. It is an environmental opportunist, and the host likely is immunocompromised. A
constant gross finding was the presence of a variable number of pale foci of necrosis, pinpoint to
approximately 2 mm in diameter throughout the liver. Microscopically, these foci were confirmed as
necrotic areas which were infiltrated by neutrophils or mixed inflammatory cells including histiocytes, and
with scattered Gram (+) coccobacilli, usually intracellular, at the periphery of the lesion.
(b) Gram-Negative bacteria
With the exception of Fusobacterium, Bacteroides and Bartonella, infections with the Gram (-) bacteria
described here are diagnosed based on a compatible suite of lesions, associated with isolation of the
agent from tissues with lesions, and from two or more parenchymatous organs, if septicaemia is
Fusobacterium necrophorum infection (Necrobacillosis)
Necrobacillosis, a necrotising inflammation involving bone and or soft tissues, may be acute or chronic,
and although caused primarily by Fusobacterium necrophorum, it may be exacerbated by concurrent
infection with a variety of other microorganisms. Fusobacterium is an environmental opportunist, present
on the ground, and in ingesta. To colonise it requires a breach in the epithelium of the skin, gingiva, oral
cavity or upper gastrointestinal tract, after which its necrotizing toxins and leukocidins promote soft tissue
necrosis with relatively little peripheral inflammation.
Necrobacillosis, especially involving the jaw (so called jaw disease or ‘lumpy jaw’), is a common disease
in captive macropods. All macropod species appear to be susceptible.
Perhaps surprisingly, animals may appear relatively normal until shortly before death – which occurs a
few days to several weeks after the initial appearance of signs. The lesions probably start at the alveolar
gingiva or at some breach in the gingival mucosa elsewhere, which may be related to trauma, dental
progression, or sharp components in the diet.
Typically, gross lesions are primarily necrotising and involve mucous membranes, but in some very acute
cases there is diffuse cellulitis of subcutaneous tissues of the face with minimal oral involvement.
As lesions develop there is characteristically an inner necrotic zone and an outer fibrous zone with both
layers enclosing pockets of pus or caseous material. Usually ulceration or fistulation is apparent. The pus
is yellow-green and has a foul odour. Bony changes in more chronic cases, as anticipated from clinical
observations, include formation of sequestra – usually involving the dental alveoli – and sub-periosteal
bone formation with increasing deformity, especially of the mandible. Extension of infection to contiguous
organs such as parotid salivary glands, nasal turbinates or brain may occur.
Visceral lesions can include multiple nodules containing yellow caseous material over the gastric serosa
and throughout the liver, and necrotising foci in the lung, liver and stomach, perhaps related to swallowing
or inhaling exudate containing massive numbers of bacteria, which set up local lesions in the lungs or
stomach, the latter metastasizing via the portal flow to the liver.
Microscopically, the essential lesion in soft tissues is focal necrosis associated with masses of tangled
Gram (-) filaments, which may be seen by careful observation in H&E sections. Other opportunistic
bacteria, such as Bacteroides and Actinomyces also may be present. Necrosis is at first coagulative but
later there is total loss of tissue structure. The bacteria may be only at the periphery, or be present
throughout necrotic areas. Necrotic foci are in turn surrounded by leukocytes, predominantly
mononuclear cells, many of which are degenerating. Beyond the leukocytes is a variable zone of
fibroplasia. Necrotising lesions within bone are comparable to those in soft tissues and may be sharply
demarcated from normal bone. Necrotic bone may become lytic and lost, and occasionally the entire
distal mandible will slough, bilaterally. Marked reactive osteogenesis also may occur, contributing to
mandibulo-maxillo-facial distortion.
Diagnosis is based on the characteristic suite of lesions, and recognition of the organism in lesion
smears or tissue section. It is anaerobic, and rarely is isolation attempted.
Bacteroides is a gastrointestinal anaerobe, most commonly recognised as an opportunistic contributing
pathogen in ‘lumpy jaw’ caused primarily by Fusobacterium infection. However, Bacteroides sp. was
isolated from lung of a long-footed potoroo with fibrinous pleuropneumonia. Bacteroides produces clumps
or microcolonies of small basophilic organisms visible in H&E sections at the periphery of areas of
coagulative-liquefactive necrosis in tissue.
Most Salmonella isolates from mammals are Salmonella enterica, ssp. enterica; the species and
subspecies names are usually dropped, and the organism is designated by serotype in normal font, but
initially capitalised (eg. Salmonella enterica enterica Typhimurium is expressed as Salmonella
In Australia, many serotypes of Salmonella have been isolated from wildlife, especially macropods, but
few reports relate particular isolates to clinical findings and even fewer describe lesions. Salmonella
Typhimurium appears to be the main serotype associated with disease.
Clinical illness, death, and or lesions due to Salmonella infection are reported in many species of
macropod, perhaps with the red kangaroo being over-represented and therefore possibly more
susceptible – although removal from its normally arid environment may have heightened susceptibility.
Importantly, salmonellosis appears not to be reported in free-ranging macropods, even though they may
frequently be carriers of infection.
Death may occur without signs being observed. When present, signs are those of enteritis and
septicaemia. Diarrhoea is the most consistent sign. In orphaned macropod joeys, loose faeces may
contain streaks of blood sometimes progressing to profuse bloody diarrhoea.
Gross findings in fatal salmonellosis may include marked petechial and ecchymotic haemorrhages,
pulmonary oedema, splenomegaly, and variably normal to fibrinohaemorrhagic intestinal mucosa, with
luminal diarrhoea, fibrin, blood and casts, depending on the type of mucosal lesion.
In two acute cases in immature western grey kangaroos, in which gross lesions were not seen, there was
microscopic focal hepatic necrosis, focal inflammation and necrosis of the muscularis of the small
intestine, and suppurative bronchopneumonia. Focal hepatic necrosis with cholangitis was also seen in a
pretty-faced wallaby with salmonellosis.
Escherichia coli
E. coli has been shown to be a significant pathogen, together with other Gram-negative bacteria, in
macropod joeys – causing enteritis with bloody diarrhoea, peritonitis, pneumonia and septicaemia. Gross
findings are those of a ‘dull’ peritoneum with occasional fibrin strands but no pus present. Extensive parts
of the lung may be reddened and oedematous or consolidated, but not necrotic.
Pseudomonas spp. are opportunistic bacteria which occasionally cause serious disease in mammals
either as primary pathogens or in association with other microorganisms.
Pseudomonas spp. are frequently isolated from cases of ‘lumpy jaw’ and have been recognised as
pathogens in association with Fusobacterium necrophorum and other gram-negative bacteria in ‘stressed’
pademelons with pneumonia.
Pseudomonas infection appears to be more prevalent and serious in macropod joeys than adults; the
organism often is isolated from the faeces of orphan joeys. Other than peritonitis and the frequent
presence of pneumonia, lesions of septicaemia in Pseudomonas spp. infection in these joeys are not
reported. But oedema, congestion, excess fluid in body cavities, and petechial haemorrhage, might be
Bordetella bronchiseptica
There are several reports of illness or mortality of wallabies associated with B. bronchiseptica infection.
At necropsy, marked congestion and consolidation of the lungs were apparent. Microscopically,
neutrophils were within bronchi and alveoli in affected lung, while in more normal areas, there was an
increased prevalence of alveolar macrophages. Subacute pneumonia and pleurisy were diagnosed.
Pasteurellosis, caused mostly by infection with Pasteurella multocida, is described in a variety of
Australian native mammals including kangaroos and potoroos.
No doubt because of its presence in the upper respiratory tract of healthy animals, respiratory lesions in
P. multocida infection are often found. Gross lesions in macropods have included bronchopneumonia,
fibrinous pneumonia or pleuropneumonia. Other gross lesions in fatal pasteurellosis in kangaroos
include haemorrhages in the gastrointestinal tract and lymph nodes.
In captive potoroos that died of pasteurellosis the lungs were diffusely red and sank partly in 10%
formalin. Severe, lobular, acute-subacute pneumonia that was sometimes necrotising and, in more
chronic cases, walled-off abscesses, were noted.
In common with several other gram-negative bacteria, Yersinia pseudotuberculosis may be isolated from
the faeces of apparently healthy wild birds and animals. Under stressful conditions, however, fatal
disease may occur.
Yersiniosis is described in a variety of Australian native mammals including kangaroos, and the red-
necked wallaby. Yersiniosis is a zoonotic disease. Yersinia infects via the faecal-oral route, so lesions are
distributed accordingly.
Macrocopically, widespread serosal petechiation and enteritis with congestion, haemorrhage and perhaps
fibrinohaemorrhagic ulceration may be observed in acute cases. But Y. pseudotuberculosis often
produces a characteristic picture of enteritis with necrosis of intestinal lymphoid tissue, mesenteric
lymphadenitis, and hepatic and splenic areas of necrosis, seen as white foci, sometimes accompanied by
consolidating embolic pneumonia.
Histologically, in affected portions of the intestine there is mucosal necrosis with mats of bacteria or
aggregates of coccobacilli forming microcolonies visible in H&E sections, along the mucosal surface and
within necrotic debris, often in gut-associated lymphoid tissue. In the more chronic cases, the discrete
pale foci seen at necropsy consist of foci of necrosis infiltrated with neutrophils and macrophages, the
latter predominating around lesions of some standing.
Proteus spp. are frequently isolated from both healthy and diseased Australian native mammals. They
seldom are incriminated as primary pathogens. Proteus spp. are frequent isolates from the faeces of
apparently normal animals as well as from those with disease.
Proteus vulgaris and P. mirabilis were isolated together with other bacteria from intestinal content of
kangaroos with fatal stongyloidosis, and from orphaned macropod joeys. Proteus morgagnii and P.
rettgeri have also been isolated from cases of pneumonia, and P. rettgeri has been isolated from a case
of peritonitis in a joey. Lesions are comparable to those in coliform infections.
Burkholderia pseudomallei is an opportunistic soil- and water-borne organism that causes meliodoisis,
which, in people, has a relatively high fatality rate. Personal protective measures should be followed
rigorously if necropsying an animal which may have died of melioidosis. Although serological surveys
indicate that exposure to Burkholderia pseudomallei is widespread in Australian native mammals,
especially in northern Australia, infection rates are not high, and there are few reports of overt disease, or
descriptions of associated lesions.
Gross findings in melioidosis in Australian native mammals appear in general to be similar to those seen
in domestic species. The pattern of lesions suggests infection via the intestinal tract, with dissemination
via the portal blood to the liver and subsequent septicaemia. In a tree kangaroo that died of melioidosis
after an observed illness of only a few days, multiple foci of necrosis were present in an enlarged,
discoloured liver. In wallabies, similar pale foci up to about 1 mm in diameter, which were sometimes
confluent, were throughout the liver and spleen, but pus was not observed.
Chromobacterium violaceum, a bacterium found in soil and water in the tropics, which occasionally
causes serious illness in man and other species, was reported as the cause of septicaemia in a young
captive agile wallaby. At necropsy the lungs did not deflate, were oedematous, and contained multiple
haemorrhages up to approximately 4 mm in diameter. Microscopically, pulmonary hyperaemia, oedema
and haemorrhage were confirmed, and fluid was present in alveoli and bronchioles. Bacteria were
prevalent throughout the lung, being most abundant in areas of exudation and haemorrhage.
Morganella morganii was isolated, in mixed culture with Bacteroides spp. and a β-haemolytic
Streptococcus from lung lesions of a common wallaroo with hypertrophic osteopathy.
Bartonella australis, a facultative intracellular Gram (-) bacterium has recently been isolated from blood of
eastern grey kangaroos in central coastal Queensland, and a number of other Bartonella species have
been recognised in fleas parasitising marsupials, including several macropods. No description of any
associated illness or lesions is available, and pathogenicity of these organisms in macropods or humans
is unknown. In view of possible human health implications, and the syndrome of anaemia and deaths of
eastern grey kangaroos associated with presence of an unidentified haemoparasite (see under protozoa),
the need for further investigation of B. australis is indicated.
Kaewmongkol, G., S. Kaewmongkol, L.M., McInnes et al. 2011. Genetic characterization of flea-
derived Bartonella species from native animals in Australia suggests host–parasite co-evolution.
Infection, Genetics and Evolution 11: 1868-1872.
(c) Spirochaetes
Review of the literature on leptospirosis is complicated by the detailed nomenclature based traditionally
on serological cross-testing, and, by the relative lack of concordance of the results of such testing with
genospecies determinations determined by DNA analysis of these organisms – which morphologically are
A number of surveys involving serology, and sometimes bacteriological culture of mostly healthy animals,
have investigated the presence and prevalence of leptospiral infection in Australian native mammals.
Antibodies against leptospires have been demonstrated in a wide diversity of species including various
macropods but no associated lesions appear to have been reported in macropods. Leptospira
interrogans may be shed in urine of carrier animals, and is zoonotic.
(d) Mycobacteria
In many Australian native mammals, the presence of acid-fast bacilli (AFB) within lesions has been
shown by culture or by other means, such as PCR, to reflect infection with Mycobacterium spp., including
M. bovis, M. tuberculosis, M. ulcerans, M. avium paratuberculosis, M. terrae, M. asiaticum, M. chelonae,
M. fortuitum, M. chitae, M. smegmatis, M. avium and M. intracellulare.
Mycobacteriosis is reported in a variety of macropods, emphasising the ubiquitous presence of mainly
opportunistic mycobacteria in the environment. In macropods in South Australia, gross lesions suggestive
of Johne’s Disease (JD), microscopic changes consistent with JD, and positive tissue culture for M.
avium subspecies paratuberculosis, indicated a likely epidemiological link between JD in domestic
ruminants and macropods.
A review of cases in macropods published up to 1986 revealed that lesions of mycobacteriosis were seen
most frequently in spleen and lymph node and less often encountered in bone, the respiratory system,
then liver, in that order. In subsequent reports, involvement of the skin and subcutis is described more
often, perhaps indicating caution in earlier reports of incriminating AFB as the primary pathogen in view of
their ubiquitous nature and frequent identification in contaminated superficial lesions – together with other
likely pathogens. The typical lesion in macropods varies from small miliary foci to massive nodules with
an internal consistency varying from purulent to caseous. ‘Grittiness’ due to mineralisation occurs
sometimes but is not a common finding.
Microscopically in macropods, lesions of mycobacteriosis consist typically of central areas of necrosis
surrounded by histiocytes and giant cells. Peripheral to these cells are aggregates of lymphocytes, fewer
plasma cells and polymorphonuclear neutrophils, and fibroplasia. Giant cells are usually present but their
prevalence is variable. Mineralisation is not a constant feature. Acid fast bacteria tend to be plentiful in
caseous areas but variable and, often rare, in more proliferative granulomatous lesions.
(e) Rickettsia
Major interest in rickettsioses is their zoonotic potential and the role native species may serve as
reservoirs of infection. Although serological surveys have demonstrated that infections with Coxiella
burnetti and Rickettsia spp. occur in a wide range of Australian native marsupials and rodents, clinical
disease is not apparent and lesions seem not to have been described. In fatal experimental infection in
one of two rufous rat kangaroos with C. burnetti, however, there was apparent splenomegaly and focal
necrosis in the liver.
Potter, A.S., M.J. Banazis, R. Yang et al. 2011. Prevalence of Coxiella burnettii in western grey
kangaroos (Macropus fuliginosus) in Western Australia. Journal of Wildlife Diseases 47: 821-828.
Respiratory aspergillosis has been observed in captive macropods including wallabies and wallaroos, but
lesions were not described. Also Aspergillus sp. was isolated from and demonstrated within oesophageal
tissues of a captive kangaroo.
Candidiasis in Australian native mammals is caused mostly by Candida albicans but other Candida spp.
such as C. catenulata, C. tropicalis and C. krusei are sometimes involved. Macropodids with candidiasis
include kangaroos, wallabies, the wallaroo, and the musky rat-kangaroo.
Candidiasis may be localised in the gastrointestinal tract, cloaca, or skin, or be systemic, so signs will
vary accordingly. Clinical examination of affected animals may reveal pale plaques or ulcers in the oral
cavity on the tongue, gums and lips – which may be swollen, and pharyngitis of varying severity. Skin,
especially around the mouth, may also be affected.
In addition to those lesions seen clinically, gross changes in kangaroos included linear white
encrustations adherent to the folds of oesophageal epithelium, and distension of the non-glandular
stomach with curd-like material much of which was adherent to the epithelium. In systemic candidiasis in
a juvenile kangaroo, multiple, discrete necrotic but firm foci up to 5 mm in diameter were present
throughout the liver. These foci were light brown and depressed below the surface.
Microscopically, although Candida preferentially invades the superficial layers of squamous epithelium, in
severe infections deeper layers of such epithelium, as well as mucosa and contiguous tissues may be
Liver lesions only were reported in one eastern grey kangaroo with systemic candidiasis, the causal
organism, C. tropicalis, presumably having metastasised from the gut, lung or some other location during
a protracted illness. Foci of necrosis in the liver were associated with many fungal elements, including
blastospores, pseudohyphae and true mycelia.
Cryptococcosis is most commonly caused by two species, Cryptococus neoformans (consisting of two
varieties - C. neoformans var. grubii and C. neoformans var. neoformans), and C.gattii (formerly C.
neoformans var. gattii or C. bacillosporus).
Cryptococcosis is reported in several diverse species of macropodids. Cryptococcal infection that is
clinically apparent seems often to be opportunistic.
Signs in a captive long-nosed potoroo initially presented with weight loss, weakness, muscle atrophy and
inappetence, included a subsequent head-tilt with circling, recumbency and visual deficits. Lesions of
cryptococcosis described in both Gilbert’s and long-nosed potoroos were those of meningoencephalitis,
with optic neuritis also being seen in the latter species.
Other deep or systemic mycoses
Pneumocystis carinii was diagnosed by microscopic examination of impression smears in a captive red
kangaroo with lesions of gastritis from which Candida albicans was isolated. In Giemsa-stained smears
eight intracystic uni-nucleated bodies were seen. These bodies were light blue and their nuclei red but the
cyst wall remained unstained. The cysts measured 5 to7 µm in diameter. With methenamine silver
staining the cysts were black and thick walled. No description of lesions was given.
Coccidioidomycosis is reported in wallaroos and a red kangaroo held in zoos overseas. Necropsy of
the kangaroo, which apparently had shown no signs of respiratory disease, revealed a solitary, firm,
discrete mineralised lung lesion measuring 11 x 8 mm, with a fibrous wall measuring 1 to 2 mm in
thickness. Microscopically, a granulomatous response was associated with spherules and free
endospores characteristic of Coccidioides.
Ringworm in wildlife species is of particular interest because of its zoonotic aspects and the occurrence of
clinical disease in carers and others handling wildlife or products thereof.
In several extensive surveys of Australian native mammals various fungi, including some potentially
pathogenic species, notably Trichophyton sp. and Microsporum sp. were isolated, but in no case was
isolation associated with clinical disease. Typical ringworm is overwhelmingly a disease of captive
animals; severe dermatophytosis caused by Microsporum persicolor was however observed in a red
kangaroo shot in the wild.
Ringworm has been reported in kangaroos, wallaroos, and wallabies. M. canis, or more often T.
mentagrophytes, have been involved.
In kangaroos ringworm may present as an area of alopecia with minor reddening of the skin and ‘little
else’. Two forms of the disease are recognised in macropod joeys. In the ‘classic’ form there are
discrete, sometimes multiple areas of alopecia with no erythema. In the more severe, generalised, form
quite large areas may be involved and the skin is roughened and thickened with associated alopecia.
There is a tendency for scabs to form. In young animals infection of the ears may lead to necrosis and
sloughing of parts of the ear.
Microscopic findings in ringworm appear to be similar across species. Skin changes are most prominent
in hair follicles, which show ortho- and parakeratotic hyperkeratosis, acanthosis and dilatation. Follicular
lumens may be full of neutrophils, fungal spores and hyphae – the latter being seen to infiltrate keratin.
Some of the follicles rupture, resulting in focal pyogranulomatous dermal inflammation. In orphan joeys it
was noted that scales of hyperkeratotic epidermis were also invaded by hyphae and spores.
Identification of the causal fungus requires other tests such as culture, but presumably, as in domestic
animals, Microsporum infections are generally characterised by a mosaic of polygonal arthrospores in an
ectothrix pattern whereas in Trichophyton infections there are chains of arthrospores in both endo- and
ectothrix patterns.
Mycotoxicosis due to sporodesmin was suspected in a two year-old eastern grey kangaroo. Death
occurred after a 3 to 4 week illness. Grossly the liver was small, firm and pale, and microscopically there
was a severe, diffuse cholangiohepatopathy with marked bile duct hyperplasia. At the time of the incident,
sporodesmin toxicity was reported in cattle in the area.
Toxoplasma infection, confirmed by pathological examination or serology is described in many Australian
native species, and it is suggested that vertical transmission may occur in macropods. Caution must be
placed on some earlier reports, which may have involved related organisms such as Neospora,
Hammondia or other tissue cyst-forming protists.
Toxoplasma infection is reported in most macropod species – in which the disease is often fulminating –
with minimal signs occurring before ultimate prostration and death.
Gross findings: Often no changes indicative of toxoplasmosis are observed at necropsy, and if present,
such changes are quite variable in severity. In a detailed correlative gross-microscopic study of
toxoplasmosis, necropsy findings (or lack of them) in macropods with fatal toxoplasmosis included: no
visible lesions, pulmonary congestion or consolidation, gastrointestinal reddening and ulceration,
myocardial haemorrhages and pale streaks, splenomegaly, cerebral malacia, adrenal enlargement and
reddening, pancreatic swelling, and lymphadenomegaly.
In this comparative study, diffuse or patchy pulmonary congestion, oedema and consolidation were
common in affected macropods, and white foci were present in lung parenchyma. Myocardial
haemorrhages were usually petechial and often interspersed with white streaks. Affected hearts were
enlarged due to retention of blood in the ventricles and atria. Gastro-intestinal changes were confined
primarily to the stomach and small intestine, and included ulceration and frequent patchy reddening, with
white foci. In the pancreas, swelling due to oedema was often accompanied by irregularly scattered white
foci of varying size. Malacic changes in the brain mostly involved the cerebral cortices.
Microscopic findings: Since gross lesions often are lacking or are inconsistent in animals with
toxoplasmosis, diagnosis usually depends on observing the characteristic microscopic changes –
associated in most cases with the free or encysted tachyzoites of T. gondii. Toxoplasmosis should be
suspected in a case with any combination of non-suppurative meningoencephalitis, non-suppurative
myocarditis, interstitial pneumonitis and focal hepatic and/or splenic necrosis. In spite of the great
variability across species in the microscopic changes seen, it seems remarkable that brain, myocardium
and lung are so consistently involved, and that the predominant changes are necrosis and some form of
non-suppurative inflammation. Whereas multi-organ, multi-focal necrosis associated with many
organisms is a feature of acute fulminating toxoplasmosis in susceptible animals, more often there is
encephalitis characterised by microglial nodules with some peri-vascular cuffing, myocarditis, and
interstitial pneumonia. In such cases organisms are sometimes numerous but otherwise may be difficult
to find, and usually are not associated directly with foci of necrosis, or with inflammatory foci in the brain.
Diagnosis in such cases is facilitated by use of specific immunohistochemical staining.
Parameswaran, N., R.M. O’Handley, M.E. Grigg et al. 2009. Vertical transmission of Toxoplasma
gondii in Australian marsupials. Parasitology 136: 939-944.
Parameswaran, N., R.C.A Thompson, N. Sundar et al. 2010. Nonarchetypal Type II-like and
atypical strains of Toxoplasma gondii infecting marsupials of Australia. International Journal of
Parasitology 40: 635–640.
Portas, T.J. 2010. Toxoplasmosis in macropodids: a review. Journal of Zoo and Wildlife Medicine.
41: 1-6.
Sarcocysts have been recognised in a variety of Australian native mammals including macropods.
Sarcocystis infections in marsupials generally appear to be innocuous, but as the early stages of infection
are pathogenic in some domestic animals, it is possible that disease may occur in marsupials – serving
as intermediate hosts – in special circumstances.
In the overwhelming number of reports, sarcocysts were found only on microscopic examination of
muscle. However, in some species they may be up to several mm in length, and thus be detected
Other Cyst-forming Apicomplexan Protists
Besnoitia spp. are characterised by production of usually multilocular intracytoplasmic cysts (meronts
containing merozoites) in markedly hypertrophic host connective tissue cells, often in superficial locations
on the body (dermis, ocular sclera, etc.). They are presumed to have a heteroxenous life cycle similar to
Sarcocystis, involving a prey species in which the meronts are found, and a predator species in which
sexual development occurs. However, a definitive host is not known for a number of the species of
Besnoitia found in large mammals, in which mechanical transmission by arthropods is suspected.
In some species the hypertrophic host cells are sufficiently large (~1 mm) to be visible to the naked eye in
superficial locations, or at necropsy.
A single case of besnoitiosis has been described in a captive western grey kangaroo in Western
Australia, and an allusion was made to besnoitiosis associated with epistaxis in wild kangaroos. Further
information is required on the prevalence and distribution of this organism before work on its biology and
significance can be determined. No Besnoitia are zoonotic, and most are probably fairly host-specific.
Anon. 2010. Besnoitia. Western Australian Animal Health Report, July 2010, Pp. 9.
Olias, P., B. Schade & H. Mehlhorn. 2011. Molecular pathology, taxonomy and epidemiology of
Besnoitia species (Protozoa: Sarcocystidae). Infection, Genetics and Evolution 11: 1564-1576.
Neospora caninum meronts were associated with myocarditis in a captive parma wallaby that died in a
zoo in Europe. Immunohistochemistry and/or molecular techniques would be required to differentiate
Neospora from Toxoplasma in such cases. While Neospora caninum is established in wild dog
populations in Australia, and causes disease in cattle, the possibility of a sylvatic cycle involving native
wildlife is speculative.
Cronstedt-Fell, A., B. Richter, T. Voracek et al. 2011. Neosporosis in a captive parma wallaby
(Macropus parma). Journal of Comparative Pathology (June 2011 - Epub ahead of print).
King, J.S., D.J. Jenkins, J.T. Ellis et al. 2011. Implications of wild dog ecology on the sylvatic cycle
of Neospora caninum in Australia. The Veterinary Journal 188: 24-33.
Intestinal and hepatic coccidiosis
The coccidia identified in macropods are Eimeria spp., more than 40 of which have been described.
Intestinal or hepatic coccidia associated with overt disease and lesions in macropods include Eimeria
kogoni and E. cunnamullensis.
Species affected: Clinical disease with lesions attributed to intestinal and or hepatic coccidiosis is
reported in eastern and western grey kangaroos; red kangaroos; and black-striped, tammar, whip-tail,
red-necked and parma wallabies.
Gross findings: As in domestic animals, the gross changes seen in coccidiosis in wildlife may reflect the
outcome of epithelial proliferation, inflammation with oedema or haemorrhage, or a combination of these
changes. Lesions in kangaroos include subcutaneous oedema, copious serous fluid in body cavities,
oedema and reddening of mesenteric lymph nodes, oedema of some viscera, and white or creamy-yellow
foci (0.5 to 2 mm in diameter) visible through the serosa of the small intestine, especially the jejunum –
these foci being more obvious in the mucosa which is eroded and haemorrhagic with blood stained
exudates in the lumen in such areas. Oedema of the wall of the small intestine is present anteriorly but
increases caudally, in association with luminal exudates changing from sero-mucoid to dark red, muco-
haemorrhagic in the jejunum. Diphtheroid changes may occur in very severe cases. Lesions are less
obvious in the ileum, and the wall of the large intestine is unaffected. Importantly, death may have
occurred so suddenly that there was no history of blood stained faeces indicating severe haemorrhagic
Lesions of coccidiosis involving both intestine and liver appear to be more common in tammar wallabies
than in other macropods. In one study, hepatic lesions were white nodules 2 to 5 mm in diameter or pale
areas surrounded by reddened borders. These lesions, which were scattered diffusely throughout the
liver, were often associated with intestinal coccidiosis.
Microscopic findings: Especially in fatal coccidiosis in macropods, schizonts are quite conspicuous, and
associated with pathological change. In one outbreak in wild eastern grey kangaroos only the small
intestine was affected, and both small and large schizonts, and both micro- and macrogametes were
present in cells of the lamina propria, sometimes with gametocytes ‘of a different type’ being present in
epithelial cells. Large schizonts, that lay deep in the lamina propria were up to 350µm in diameter but
were again arranged in clusters of 2 to10 individual schizonts, the conglomerate having an overall
diameter of up to 700 µm, and sometimes a rosette-like appearance. Microgametocytes in the lamina
propria were scarce, but macrogametes were numerous. Rupture of large schizonts sometimes resulted
in heavy infiltration of polymorphonuclear neutrophils. Both intestinal and hepatic lesions are expected in
tammar wallabies with coccidiosis. Schizogony is seen initially in the small intestine but later it occurs in
the liver.
The taxonomy of Cryptosporidium is dependent on molecular and biological characterisation, and is still
in a state of flux. Cryptosporidium has been recognised, based on oocysts in faeces or stages in intestinal
tissue sections, in a number of Australian marsupials, including the red, eastern and western grey
kangaroos, the red-necked wallaby, the swamp wallaby, the yellow-footed rock wallaby, Tasmanian and
red-necked pademelons, and the bilby. Cryptospridium fayeri has been characterised from the koala, and
C. macropodum from the eastern grey kangaroo; both species have been found in macropods. Other
genotypes from Australian marsupials await further characterisation before they can be described as
species. C. muris, probably originating in rodents, was detected in bilbies in a captive colony.
Gross abnormalities associated with Cryptosporidum infection include distension of the intestines with
gas and watery fluid, and perhaps congestion. Microscopically there may be mild to moderate villous
atrophy, crypt hyperplasia, some focal necrosis with loss of epithelium, and light to moderate infiltration of
the lamina propria with predominantly mononuclear cells. Some metaplasia to low columnar, cuboidal or
even squamous epithelium may occur.
Good cytology, necessitating minimal autolysis and therefore prompt fixation of infected intestine at
necropsy, is required for ready recognition of cryptosporidia in histological sections. In sections stained
with haematoxylin and eosin the parasites appear as basophilic bodies apparently attached to the surface
of cells, sometimes giving the microvillus brush border a ‘spotted granular appearance’. They are
spherical to elliptical in shape measuring 2 to 6 µm in diameter and protrude from the cell surface. Use of
special staining, especially Ziehl Neelsen, may help recognition of oocysts within the gut lumen or faeces.
Fayer, R. 2010. Taxonomy and species delimitation of Cryptosporidium. Experimental
Parasitology 124: 90-97.
Power, M.L. Biology of Cryptosporidium from marsupial hosts. Experimental Parasitology 124: 40-
Cyst-forming protists of the genus Klossiella parasitise the kidneys of several macropodid species, as
well as other marsupials. The presence of Klossiella is an incidental finding. There is no clear association
of the parasite with clinical disease, and gross lesions are not apparent. Microscopically, interest centres
on the parasite as almost always, an inflammatory reaction is absent or minimal. All stages of the life
cycle of the parasite may be seen in sections of kidney and the nephron may be involved at various
levels, necessitating a search especially of cortex but also contiguous medulla.
Infection with Leishmania sp. has been diagnosed as the cause of granulomatous dermatitis in captive
red kangaroos, and subsequently in wild northern wallaroos, a black wallaroo and agile wallabies.
Clinically, lesions presented as thickened, hairless and centrally ulcerated areas on the tail or ear, the
margin of which was in one case deformed by the lesion. Lesions often began as hairless papules that
became centrally encrusted, then later ulcerated as the crust fell away. Microscopic examination revealed
hyperkeratosis, acanthosis, focal dermal necrosis and extensive granulomatous inflammation. The
cytoplasm of macrophages within the dermis was seen to contain multiple round organisms with small
basophilic, eccentric nuclei. Molecular studies have confirmed this organism as a probably novel species
of Leishmania, which is transmitted by a day-feeding midge. The possible zoonotic significance of this
agent is yet to be determined.
Dougall, A., C. Shilton, J. Low Choy et al. 2009. New reports of Australian cutaneous
leishmaniasis in Northern Australian macropods. Epidemiology and Infection 137: 1516-1520.
Dougall, A.M., B. Alexander, D.C. Holt et al. 2011. Evidence incriminating midges (Diptera:
Ceratopogonidae) as potential vectors of Leishmania in Australia. International Journal for
Parasitology 41: 571-579.
Most reports of Trypanosoma spp. infection in Australian native species relate to recognition of the
parasite in blood smears, or more recently from PCR analysis of blood samples collected as part of
broader surveys. Infected indigenous species include the eastern grey kangaroo, and (following
experimental infection), the agile wallaby. In most of the reports, presence of trypanosomes was not
associated with clinical disease or lesions.
Experimental infection of agile wallabies and dusky pademelons (Thylogale brunii) with Trypanosoma
evansi, the agent of surra, endemic in south Asia, resulted in death or sickness, including anaemia.
Gross lesions varied considerably but included pericarditis, serous atrophy of fat, splenomegaly,
ulcerative gastritis and enteritis. Microscopically, there was mononuclear cell infiltration of the connective
tissue of most organs with little cellular destruction – striking lesions being apparent in the choroids,
heart, stomach and small intestine. In histological sections the trypanosome nuclei were seen as coccoid
structures approximately 0.5 µm in diameter located in the interstitial tissue of many organs. Larger
basophilic structures, 1 to 2 µm in diameter, and presumably representing more complete forms of the
parasite, were occasionally seen within vacuoles in the stroma.
Other haemoprotist infections
There are reports of presumed Babesia infection in a rock-wallaby, unassociated with illness, and
infection of an eastern grey kangaroo diagnosed by examination of a blood smear, then PCR. In the
kangaroo – which recovered with treatment – there was a significant parasitaemia, and signs included
dehydration, depression and anaemia (PCV of 21%).
Haemoprotists in young eastern grey kangaroos. Since 1994 a syndrome of severe anaemia
associated with infection by an unidentified haematozoan has been recognised on the north coast of New
South Wales. In addition to anaemia there is a tendency to bleed when attached ticks are removed.
Pleomorphic intraerythrocytic parasites are seen in blood smears, and examination of histological
sections reveals sequestration in a range of organs and variable formation of schizont-like forms within
blood vessels, these latter changes being most marked in renal glomeruli, where schizont-like forms
distend the capillaries of glomerular tufts.
Other non-haematological protists
These infections include steatitis associated with a coccidia-like protist in a red kangaroo, and giardiasis
in several macropodid species.
Information on helminth parasites of macropods is found in reviews and papers cited in Ladds (2009) as
well as in the reviews and check-lists below. Beware: while the players don’t change, their names
sometimes do!
Beveridge I. (1993). Marsupial parasitic diseases. In: M.E. Fowler (ed) Zoo and Wild Animal
Medicine, vol 3. Saunders, Philadelphia. Pp. 288-293.
Beveridge, I., D.M. Spratt & P.M. Johnson. 2010. Diversity and distribution of helminths in
macropodid marsupials. In: G. Coulsen & M. Eldridge (eds). Macropods. The Biology of
Kangaroos, Wallabies and Rat-kangaroos. CSIRO Publishing, Collingwood. Pp. 231-242.
Spratt, D.M., I. Beveridge & E.L. Walter. 1991. A catalogue of Australasian monotremes and
marsupials and their recorded helminth parasites. South Australian Museum, Adelaide. Pp. 105.
Echinococcus granulosus
Although infection with this cestode may cause debility or illness in an intermediate host, the disease
complex, hydatidosis, is of particular interest because of its impact on spill-over domestic animal hosts
and on account of its zoonotic implications.
The definitive host is the dingo or dog. Many macropod species are intermediate hosts for E. granulosus.
Swamp wallabies may be especially susceptible, while in northern Australia the black-striped wallaby is a
major intermediate host.
In macropodid intermediate hosts, hydatid cysts were found mostly in the lung and thoracic cavity,
including attachment to the diaphragm, and less often in the liver and peritoneal cavity. Cysts were uni- or
multilocular, and varied in size from less than 1 cm up to 10 cm in diameter. Multilocular cysts measuring
45mm have been observed to contain daughter cysts 10-18 mm in diameter. Disseminated infection with
multiple small cysts in both thorax and abdomen has been reported. Unilocular cysts have been
observed in the kidney, and in one rock wallaby with multiple hydatid cysts, it was estimated that less than
10% of pulmonary tissue was functional. Degenerate cysts were sometimes caseous or calcified.
Cysts in intermediate hosts can be categorised as fertile or sterile based on their microscopic
appearance. In macropods the majority were fertile, with an inner, thin, germinal layer of small cells from
which small hooked protoscolices might be seen budding, outside which was a distinct laminated
cuticular zone. This in turn was surrounded by a tissue reaction consisting of a rim of histiocytes and
perhaps some multinucleate giant cells, and an outer layer of fibrous tissue infiltrated by eosinophils,
polymorphonuclear neutrophils, and lymphocytes. In involuting cysts, reduction of the cyst lumen was
apparent, accompanied by thickening and folding of the cuticular laminae and prominent local fibrosis.
Even in lesions in which involution is well advanced, at least fragments of the folded wall of the hydatid
cyst remain and can be identified by their typical laminated, refractile appearance.
Barnes, T.S., A.W. Goldizen, J.M. Morton, et al. 2011. Cystic echinococcosis in a wild population
of the brush-tailed rock-wallaby (Petrogale penicillata), a threatened macropodid. Parasitology
135: 715-723.
Barnes, T.S., L.A. Hinds, D.J. Jenkins, et al. 2011. Comparative pathology of pulmonary hydatid
cysts in macropods and sheep. Journal of Comparative Pathology 144: 113-122.
Progamotaenia spp.
Progamotaenia spp. are found in the small intestine, where they are not associated with lesions, and in
the bile ducts, where they are. Some species of Progamotaenia may be up to 1 metre long. Infection is
reported in many macropodid species. Although species such as P. effigia and P. diaphana occur, P.
festiva, is most often associated with lesions.
Grossly, up to 20 tapeworms may be found in the gall bladder and bile ducts, where they may cause
cystic dilation of the major bile ducts, associated with masses of strobila with large proglottids. The bile
duct walls in these areas typically are somewhat thickened.
Microscopic examination reveals a minimal inflammatory reaction, and changes associated with
irritation of the mucosa by the parasites. There may be hypertrophy and hyperplasia of the mucosa of bile
ducts and the gall bladder with resultant thickening, mild cholecystitis and cholangitis with a
predominantly mononuclear cell infiltration, and usually slight fibrosis of bile ducts and surrounding tissue.
Focal lesions in macropodid intermediate hosts caused by metacestodes of several tapeworms including
Anoplotaenia dasyuri, Dasyurotaenia sp., and Taenia (Multiceps) serialis are described. These lesions
present as pale 1-2 mm diameter foci in viscera or as subcutaneous cysts, with a thin fibrous wall, mild
chronic inflammation, and within which a larval cestode is recognisable histologically.
Major alimentary tract nematodes
The nematode parasites of Australian native mammals, particularly macropods, often are impressive in
their prevalence, mass, magnitude and diversity. In the case of kangaroos, for example, up to 40
nematode species, all belonging to a single order, occur in the complex saccular fore-stomach of
individual host species. In most cases, however, even heavy worm infestations are not detrimental to the
host. Aspects of major gastro-intestinal nematode infections in macropods are as follows:
Labiostrongylus spp.
Adults up to 12cm but only 3
stage larvae pathogenic
Larvae penetrate lymphoid tissue at junction of squamous and glandular parts of stomach to
cause chronic sclerosing inflammation
No overt clinical signs
Gross – mucosal hypertrophy/hyperplasia
Microscopic – if acute see many intralesional larvae associated with erosion; if chronic see
‘chronic irritative hyperplastic’ mucosal lesion
Globocephaloides spp.
Not normally pathogenic
Small (~ 1 cm dia.) worms suck blood
In fatal cases (related to worm burden in juvenile animals) see worms in proximal small intestine
associated with haemorrhage
Microscopic – haemosiderin-filled macrophages in duodenal lamina propria
Strongyloides spp.
Quite small worms (up to ~4 mm) present in stomach
Only fatal in captive host animals
Gross – erythema, oedema and haemorrhage, especially near pylorus. Mucosal hyperplasia
apparent as folds or nodules
Microscopic – severe erosion sometimes progressing to ulcers or abscesses. Larvae present in
‘tunnels’ in epithelium with caudal ends protruding into gut lumen
Rugopharynx spp.
Adults up to 10 mm free in stomach lumen; probably only larvae pathogenic
Gross – pale, firm nodules extend to junction of squamous and glandular epithelium. Larval
heads in nodules with tail ends protruding into gut lumen
Microscopic – fibroblastic reparative response. PAS-positive material around worm heads with
associated necrosis & fibrosis. Larvae absent from more chronic lesions
Other nematodes causing, or associated with lesions of the alimentary tract
In addition to the major nematodes considered above, some other nematodes have been causally
associated with lesions of the alimentary tract of macropods; these include Cyclostrongylus sp.
(oesophagus), Spirostrongylus sp. (oesophagus and stomach), Parazonialaimus collaris (stomach),
Filarinema spp. (stomach and intestine), Hypodontus sp. (small and large intestine), and
Paramacropostrongylus toraliformis (colon and caecum). In most cases these nematodes are non-
Hepatic and biliary nematodes
Hepatitis caused by Capillaria sp., probably C. hepatica, is described in captive macropods.
Macroscopically, irregular white nodules up to 5mm in diameter are scattered throughout the liver, and
there may be adhesions between the liver and other viscera. Microscopically, aggregates of capillarial
eggs, and sometimes adults are present in hepatic parenchyma. Early egg accumulation causes little
cellular response, but later, connective tissue and mononuclear inflammatory cells progressively surround
an infiltrate affected areas. Mineralisation, giant cell accumulation and extensive fibrosis may ensue, and
in some late cases eggs may not be seen.
Cardiovascular nematodes
Durikainema sp.
Small (< 3 mm) worms in blood and lymph vessels, especially in liver, epicardium
In macropods regarded as an incidental finding (eastern & western grey kangaroo, eastern
wallaroo, red-necked wallaby, agile wallaby, spectacled hare-wallaby, Tasmanian pademelon,
Lumholtz’s tree kangaroo)
Gross – nodular yellow foci 1-2 mm diameter, especially on hepatic serosa
Microscopic – depends on stage; at first have fragmentation of muscle layer of veins. Later
obliteration of vein wall, recanalisation and increasing fibrosis; many eosinophils present
Angiostrongylus cantonensis
Now reported in several macropod species
History of nervous signs in red-necked wallabies (RNW)
Gross – in RNW and rufous bettong – congestion and haemorrhage in brain or spinal cord
associated with nematodes
Microscopic changes in RNW and the bettong included haemorrhage and thrombosis, malacia,
and severe eosinophilic meningoencephalitis associated with worms
Breinlia spp.
Large filarioid nematodes identified as Breinlia ventricola were described in free-ranging red kangaroos in
Western Australia. Many worms were detected in the right ventricle and pulmonary arteries of apparently
healthy animals killed in a game meat export abattoir. Length of worms was up to 22 cm and 26 cm for
male and female worms, respectively.
Breinlia woerlei are worms 14 to18 cm in length that occur in the right ventricle and cysts in the lung of
narbarlek and the short-eared rock-wallaby. Large pulmonary cysts may compromise respiration.
Body cavity nematodes
Breinlia mundayi
As well as being intravascular nematodes, several species of Breinlia occur within the body cavities of
various macropodid species, possibly causing mild serositis with consequent fibrin tags or adhesions –
sometimes being sufficiently extensive to cause constrictive pericarditis. In B. mundayi infection of
swamp wallabies, microscopic examination revealed mild eosinophil infiltration and fibrosis on the surface
of many organs, including lungs, heart, spleen, liver and kidneys. Calcified nematodes were also found
encapsulated in the omentum. Eosinophil infiltrations around blood vessels in the heart, hepatic portal
tracts and renal cortex were considered to be reactions to circulating microfilariae. Focal granulomas in
red pulp along the margin of the spleen were associated with sequestered microfilariae.
Ophidascaris (Amplicaecum) robertsi
This ascarid occurs in pythons, and uses small mammals as intermediate or paratenic hosts, where
infective larvae develop. Migration of Ophidascaris larvae, especially in the liver, was considered the
cause of death in recently captured musky rat-kangaroos.
Connective tissue nematodes
Pelecitus roemeri (formerly Dirofilaria roemeri)
Found in at least 5 genera of macropods
Appear not to cause illness
Large nematodes – up to 14 cm in length
Gross – in subcutis, especially in vicinity of knee. May be free in fascia or encapsulated.
Depending on stage of infection, discrete hard ‘pellets’ may be seen
Microscopic – changes vary between species but include granulomatous inflammation,
mineralisation, and viable and degenerating microfilariae
Breinlia annulipapillatum
This filarioid nematode has been identified in the subcutis of black-striped wallabies, with splenic
granulomas surrounding degenerating microfilariae.
Respiratory nematodes
The significance of lung parasites to the health of marsupial hosts is poorly understood. The list of
parasites is long, but most infections do not cause overt disease, and in the majority of cases, associated
lesions are minimal.
Marsupostrongylus spp.
A number of Marsupostrongylus spp. and related metastrongyles occur in the respiratory tracts of many,
diverse marsupials including many macropods. These lungworms are found mostly in the terminal
bronchioles but are reported in the alveoli, larger bronchioles, bronchi and trachea. Clinical signs
attributable to Marsupostrongylus seem to be rare and most lesions due to infection are microscopic.
Capillaria spp.
In respiratory capillariasis the nasal sinuses or lungs may be affected. Infection has been reported in
bettongs, and potoroos. Gross lesions in uncomplicated cases were confined to the lungs, which
contained many pale yellow-grey slightly raised foci 1 to 5 mm in diameter containing thick brown mucus,
and scattered throughout the parenchyma of all lobes.
Microscopically, lesions mainly were centred on airways. There was bronchiectasis, and accumulation of
necrotic debris, desquamated epithelial cells, polymorphonuclear neutrophils, and nematode eggs within
bronchial and bronchiolar lumina. Nematodes were located on or within the bronchial and bronchiolar
epithelium, causing erosion and necrosis. Infiltrates in bronchiolar epithelium and to a greater extent in
the lamina propria, muscle layer and adventitia, were dominated by lymphocytes, macrophages and
plasma cells, but not eosinophils.
In contrast to cestodes and nematodes, trematode infections of most macropods are uncommon, no
doubt related to habitat and presence of the required intermediate hosts. Except fascioliasis, reports of
their causing disease are rare.
Macropods infected with Fasciola hepatica include kangaroos, wallabies, and pademelons.
Infected macropods may have no clinical signs, or may show severe cachexia and anaemia.
Even when large numbers of flukes are present, however, signs of illness may not be apparent
At necropsy, up to 80 flukes have been counted in red-necked wallabies
Changes associated with flukes have included severe distortion of the liver with excessive
fibrosis, and cystic swelling of the bile ducts
Microscopic changes in fascioliasis clearly vary with host susceptibility or resistance. Mild to
severe cholangiohepatitis is the essential lesion. Widespread multi-focal haemorrhage and
necrosis of hepatic parenchyma due to migrating immature flukes may occur – with subsequent
scarring, and eosinophil infiltration around bile ducts.
Paramphistomiasis in agile wallabies
Two paramphistomes, Macroptrema pertinax, and Gemellicotyle wallabicola may cause gastrointestinal
lesions in the agile wallaby but these are of a localised nature and seem to be of little consequence to
health of the host.
(a) Pentastomes
Mammals, including humans, may serve as both definitive and intermediate hosts for pentastomes,
worm-like arthropod parasites. A single pentastome nymph was detected at post-mortem of a free-
ranging bridled nailtail wallaby.
(b) Mites
Sarcoptic mange has been reported in agile wallabies and a wild swamp wallaby, among macropods.
Sarcoptes infection is a zoonosis.
Lesions in wallabies had varied from generalised over much of the body, through involving mostly
anterior parts of the body, to affecting mainly the hindlimbs, tail and caudal trunk. Lesions
consisted of thick crusts, sometimes with deep fissures.
Histopathology of sarcoptic mange lesions was characterised by a thickened epidermis, marked
hyperkeratosis with frequent mites deep within the keratin layer of the epidermis, and a
predominantly mononuclear cell accumulation in the dermis. Mite eggs and bacterial colonies
were seen superficially associated with an infiltrate of mixed inflammatory cells.
Holz, P.H., G.M.B. Orbell & I. Beveridge. 2011. Sarcoptic mange in a wild swamp wallaby.
Australian Veterinary Journal 89: 458-459.
Diabolicoptes, formerly known only from the faeces of aTasmanian Devil, is a sarcoptiform mite which, in
concert with lice (Heterodoxus wolabati), was associated with dermatitis in free-ranging swamp wallabies.
Signs included alopecia and hyperkeratosis of the pinnae and tail, over lateral parts of the body and at the
tail base, inguinal area and inner aspects of the thighs. Acanthosis, hyperkeratosis and superficial
predominantly lymphoplasmacytic perivascular dermatitis were evident, complicated by pyoderma and
superficial dermatophytosis in some areas. Mites (Diabolicoptes), eggs and pigmented debris were in
hair follicles on the inner aspects of the thighs.
Portas, T.J., A. Crowley & J. Hufschmidt. 2009. Ectoparasitic dermatitis in free-ranging swamp
wallabies (Wallabia bicolor) in New South Wales. Australian Veterinary Journal 87: 160-162.
Trombiculid mites
An extensive moist pustular dermatitis affecting the inguinal, abdominal and axillary regions of a
wild-caught yellow-footed rock-wallaby was associated with mites identified as Odontacarus
(Leogonius) adelaideae. Microscopic examination of tissue from the edge of a lesion revealed
mites within invaginations of the epidermis – the infolded, attenuated epidermis being lined by a
laminated eosinophilic to hyaline membrane (stylostome), with a mite located in the lumen. The
dermis surrounding the stylostome was heavily infiltrated by polymorphonuclear neutrophils,
many eosinophils and mononuclear cells, especially macrophages.
Heavy infections of grey kangaroos with a related trombiculid mite, Trombicula sarcina (also
called Eutrombicula sarcina) caused shallow crater-like ulcers on the inner surface of the thighs.
The colonies of mites appeared as orange coloured patches – sometimes arranged as a short
chain of lesions each about 6 mm in diameter and harbouring hundreds of mites. Such lesions,
however, did not appear to cause irritation – such as occurs in human trombidiosis.
Trombiculid mites identified as Eutrombicula hirsti were commonly found embedded in, and
associated with dermatitis of skin – again on the medial aspects of the thighs – of wild agile
wallabies. Surrounding the attachment site of mites the skin was inflamed for up to 5 mm, with a
central depression containing encrustations.
In a study of parasites on free-ranging, endangered bridled nailtail wallabies, four species of
trombiculid mites (E. hirstii, Odontacarus sp., Guntheria philippensis, and another Guntheria
sp.), located in the inner aspect of the pinna and inner thighs were associated with scab
formation, local erythema and alopecia. E. hirsti were closely associated with the skin surface,
which was hyperkeratotic, with lymphoplasmacytic and eosinophilic infiltrates in the dermis.
Old, J.M., J. Lowrey & L.J. Young. 2009. Scub-itch mite infestation in the endangered bridled
nailtail wallaby. Australian Veterinary Journal 87: 338-341.
Dermanyssid mites
The dermanyssid mite, Thadeua serrata, has been identified as the likely cause of dermatitis in free-
ranging Proserpine rock-wallabies and black-striped wallabies. Clinically, lesions were present on the
sparsely haired axillary and inguinal regions of all wallabies examined, with lesions being more
conspicuous in the inguinal area. These lesions were crateriform, and approximately 5 mm in diameter
with a central pit. In heavy infestations, lesions were confluent and involved much of the hairless areas. In
some instances the application of external pressure resulted in the extrusion of mites.
Microscopically, the crateriform lesions containing mites were seen to extend into the superficial dermis.
The crater walls were hyperkeratotic, and within the dermis there was a mixed inflammatory infiltrate
composed predominantly of polymorphonuclear neutrophils, eosinophils and lymphocytes.
Other cutaneous mites
Cytostethum sp.
Mild superficial lesions in trapped long-footed potoroos, with hair loss and abrasions due to pruritis, were
associated with Cytostethum sp. mite infection. Health of infected animals did not appear to be adversely
affected and lesions resolved after several months.
(c) Ticks
It is unclear to what extent hypersensitivity-allergic reactions to ticks occur in native animals; the severe
local and systemic responses that have been seen in man are not reported but there is one early record
of neurological signs being observed in a kangaroo immediately after an engorged kangaroo tick
(Ornithodorus [syn Argas] gurneyi) had dropped from it.
In other studies, pet kangaroos and wallabies were considered to have succumbed to tick paralysis. The
occasional cases of tick paralysis in wildlife species that are normally regarded as immune, have given
rise to considerable speculation on the nature of this immunity. At least three species of tick, namely
Ixodes holocyclus, Ixodes cornuatus, and Ixodes hirsti have been incriminated as definitely causing tick
paralysis in Australian native mammals.
Lesions have not been described in native species with tick paralysis, but presumably findings in most
cases were those attributable to ascending paralysis with secondary infection, especially bacterial
In red kangaroos shot in the wild, blemishes – so-called ‘pocks’– resulting in the commercial downgrading
of skins, were attributed to infestation with Amblyomma trigutattum. Grossly, the lesions were considered
to be attachment sites.
(d) Fleas
A flea identified as a primary or contributing cause of lesions in a range of captive macropods is the
stickfast flea Echidnophaga spp. Animals with large flea burdens are usually stressed, debilitated, or
anaemic, perhaps with other concurrent disease.
Stickfast fleas in macropods were observed to be located on the inside of the ears, around the muzzle, on
the supraorbital ridges or tarsus, at the base of the neck, or on the back between the shoulder blades.
The presence of fleas was directly associated with marked alopecia, and in some cases there was also
slight excoriation of the skin. It was presumed these lesions were due to irritation with scratching and self-
(e) Other arthropod ectoparasites
In bridled nailtail wallabies, the presence, over much of the body, of large numbers of the louse,
Heterodoxus sp., was associated clinically with frequent scratching, matted fur, bare skin patches
and wounds.
Larvae of the kangaroo bot-fly Tracheomyia macropi have been recorded in the trachea and
occasionally the bronchi and bronchioles of kangaroos and the wallaroo. Compromised
respiratory reserve with severe infestation may render animals more prone to predation. Grossly,
the larvae move freely over the mucosal surface, but if an attempt is made to dislodge a living
specimen, the ‘firmness of the attachment is surprising’. Burdens of 2 to 10 larvae per animal are
recorded and there may be associated erythema of mucosa and slight ulceration. Microscopic
changes include mucosal ulceration, mononuclear cell infiltration of the submucosa, and
squamous metaplasia and fibrosis of tracheal mucosa.
Overseas, kangaroos and a wallaby in a zoological garden suffered Cuterebra sp. myiasis over a
two month period during late summer – early autumn. Discharging lesions were located over the
thorax or on the lateral aspect of a hindlimb. Cuterebra spp. are not reported in Australia.
Severe infestations of kangaroos, wallabies and the wallaroo, with the sandfly Austrosimulium
pestilens, have been the cause of intense irritation. Large numbers of sandflies in the facial area
were associated with almost complete closure of the eyelids and marked swelling of surrounding
areas. There was also oedema of the jaws and muzzle, which in some animals were denuded of
hair and were inflamed, presumably as a result of scratching.
Other reports of fly worry in kangaroos and wallabies include bites by a number of hippoboscid
Lead poisoning
All species are susceptible. Lead poisoning was diagnosed as the cause of death of an eastern grey joey
that had lead shot embedded in its musculature, although in most species lead is not absorbed from
embedded shot. The joey developed a severe microcytic non-regenerative anaemia and lead
concentration in the liver was 13 ppm. Lesions were not reported.
Gross changes, other than injuries secondary to nervous dysfunction and resulting trauma, are not
observed in animals with lead poisoning.
Fluorosis caused illness and deaths of kangaroos inhabiting heath and farmland surrounding an
aluminium smelter.
Grossly, there was severe osteophytosis on the distal tibia and distal fibula, on the periarticular aspects of
the calcaneus, and the distal calcaneal process. In one kangaroo, which also had extensive
osteophytosis and ankylosis of coccygeal vertebrae, the fourth metatarsus was fused to the tarsal bones.
In joints, the surface cartilage was yellow and was moderately fibrillated, with focal areas of cartilage loss.
Marked longitudinal grooves were apparent on the joint surface, and several chondromas had developed
at the transitional zone of the synoviae. The upper incisors of affected kangaroos were variably
roughened, dull and stained rather than being smooth, shiny and white. Focal enamel hypoplasia, and in
one animal abnormal wear, was apparent. The upper and lower molars were also worn unevenly.
Histopathological examination of a range of tissues from affected kangaroos essentially revealed only
incidental changes. Bone fluoride levels for animals of comparable age were elevated in the population
near the smelter, in comparison with a control population.
Clarke, E., I. Beveridge, R. Slocombe et al. 2006. Fluorosis as a probable cause of chronic
lameness in free-ranging eastern grey kangaroos (Macropus giganteus). Journal of Zoo and
Wildlife Medicine 37: 477-486.
Husfschmidt, J., I. Beveridge, G. Coulson et al. 2011. Bone fluoride concentrations of eastern grey
kangaroos (Macropus giganteus) resident near an aluminum smelter in south-eastern Australia.
Ecotoxicology 20: 1378-1387.
Pesticide toxicity
Organochlorine poisoning is reported in kangaroo joeys that were immersed (except for the head and
neck) in a 1% DDT emulsion for a few seconds to control a severe infestation with the stickfast flea
(Echidnophaga gallinacea). The first signs of toxicity were observed some hours after immersion and
included intermittent convulsions, high jumping, ‘thrashing around’, terminal muscle twitching and death
within an hour of showing initial nervous signs. Necropsy findings were not reported.
Fluoroacetate poisoning
Deaths of wildlife species may occur either as a result of ingestion of sodium fluoroacetate (compound
1080) used to control vertebrate pests, or after eating fluoroacetate-containing plants such as heartleaf
(Gastrolobium spp.). In Western Australia, several species of mammal, including western grey
kangaroos, have been observed to be tolerant to fluoroacetate, indicating an evolutionary adaption to this
toxin in plants.
Clinical signs of 1080 poisoning are typically seen about 30 minutes to three hours following ingestion,
and death may occur within hours or after several days. In most studies of 1080 toxicity, lesions – due
presumably to heart failure – were either not present or not described.
Anticoagulant poisons
Second generation anticoagulant vertebrate pesticides such as brodifacoum may kill an animal after one
feeding. They are considerably more toxic than first generation anticoagulant pesticides such as warfarin
) or pindone, which require multiple feedings in order to kill.
Reports of pindone poisoning in free-ranging native mammals in Australia include western grey
kangaroos. Based on observations in dogs poisoned with first generation anticoagulants, signs do not
occur until several days after exposure and include weakness, pale mucous membranes, epistaxis,
vomiting of blood and rectal bleeding. Blood may be coughed up and haemorrhages may be apparent in
the skin or on mucous membranes. Lesions seen at necropsy include the pallor of anaemia, with
haemorrhage – ranging from petechiae to major extravasations – in or on various organs, and perhaps
into the gut.
Plant poisonings
Yew (Taxus baccata) poisoning is described in red-necked wallabies which died within 24 hours
of ingesting leaves of the plant. Necropsy revealed congestion of kidneys, myocardium, liver and
lungs, and acute enteritis was apparent. Microscopic lesions in the brain were indicative of
circulatory disturbance.
Rhododendron (Rhododendron spp.) toxicity was suspected in a young, hand reared, western
grey kangaroo which was observed eating the plant several hours before initial signs developed.
Signs were suggestive of gastrointestinal pain and spasm. After treatment with a range of agents
over the following week the animal returned to normal. Lesions were not reported.
Lantana camara poisoning in red kangaroos captive overseas resulted in hepatoxicity with
secondary photosensitisation. At necropsy, in addition to jaundice, the liver was enlarged with
pale yellow to red-yellow mottling. Microscopic changes included hepatocellular enlargement with
vesiculation of the nuclei, and sporadic feathery degeneration of the cytoplasm.
Also in red kangaroos, free-ranging in areas where pyrrolizidine-containing plants occur,
hepatosis typical of pyrrolizidine alkaloidosis has been observed.
Parsonsia straminea (monkey rope, silk pod), a woody climbing vine, was associated with ataxia,
grinding of teeth and cerebral oedema in eastern grey kangaroos kept in an enclosure in south-
east Queensland.
Neuronal pigmentation characteristic of chronic phalaris poisoning is recorded in captive red
kangaroos and wallabies grazing phalaris-dominant swards.
Poisoning following ingestion of the popular hedge and garden plant Duranta erecta (golden
dewdrop, Sheena’s Gold, Geisha Girl) is reported in kangaroos. Signs were those of drowsiness.
Lesions were not described; in (sometimes fatal) poisoning in the dog and cat there may be
gastro-intestinal haemorrhage with melena.
Oxalate poisoning
Oxalate nephrosis of suspected plant origin or of unknown cause or pathogenesis, is reported in a
swamp wallaby and in Gilbert’s potoroos (see under diseases of unknown aetiology) respectively.
Gross examination of the wallaby revealed stippling of the surface of the kidney, with ‘streakiness’ of the
cortex apparent on the cut surface. Microscopically, masses of oxalate crystals were in distended tubules
but the associated inflammatory response was minimal and there was no evidence of fibroplasia. It was
concluded that the likely source of oxalate was fresh-cut kikuyu grass (Pennisetum clandestinum), that
possibly was also contaminated with soursob (Oxalis pes-caprae).
Mebendazole toxicity
Following ongoing deaths of macropods due to a hitherto undescribed haemorrhagic septicaemic
syndrome (HSS) characterised by an absence of a neutrophilic response to bacterial infection, the
possible role of prior dosing of animals with mebendazole was investigated in pademelons.
Lesions observed at necropsy included haemorrhages in many organs including lungs, heart, liver,
muscle and gastrointestinal tract – which was ulcerated in one location and associated with peritonitis.
Microscopically, there was diffuse ulcerative necrosis of intestinal mucosa with associated proliferation of
bacterial rods. A mild, non-suppurative inflammatory response was apparent. Bone marrow from the tibia
was haemorrhagic and necrotic, with severe depletion of haemopoietic cells. Bacteria were observed in
bone marrow and lymphoid tissue in separate animals and a range of opportunistic enteric bacteria was
cultured from blood or internal organs. It was concluded that illness and deaths were due largely to a
compromised inflammatory response and that macropods were probably more sensitive to the effects of
mebenzadole on bone marrow than humans and other animals.
For neoplasms and proliferative lesions submitted from 402 terrestrial mammals to the Australian
Registry of Wildlife Health between 1974 and late 2005, a total of 43 (~ 11%) were from macropodids.
Some information on these neoplasms is presented in Table 1.
Table 1 - Final or provisional diagnoses of archived cases of neoplastic-proliferative lesions in
macropodids in the Australian Registry of Wildlife Health
Lymphoma - lymphosarcoma;
mastocytoma; osteosarcoma
adenocarcinoma, (of
mammary gland, and
bronchiogenic); squamous
cell carcinoma (of
pancreatic or bile duct);
Melanoma (of
Lymphoma – leukaemia; possible
hamartoma (of liver);
haemangiosarcoma; carcinoma,
Probable hepatoma;
adenocarcinoma (of
mammary gland –
metastatic to liver and
lung); adenocarcinoma,
cutaneous, and probable
hepatic); squamous cell
carcinoma; papilloma
Lymphosarcoma; angioma (of
spleen and of liver);
Carcinoma (of duodenum)
Adenoma (of thyroid);
adenocarcinoma (biliary,
and probable mammary)
Lymphoma - leukaemia Carcinoma, bronchiogenic Melanoma (of
Liposarcoma Adenocarcinoma, of
mammary gland
Fibrosarcoma, metastatic
* = number of cases
In addition, as well as all of the above neoplasms or proliferations in macropodids, a review of published
cases – many from overseas zoos – revealed that only a minority were mesenchymal, the overwhelming
majority being epithelial. These published cases, grouped according to histogenesis, are as follows:
Mesenchymal - Vasoformative proliferations – probably hamartomas, blast cell lymphoma, lipomatosis,
osteochondromatous proliferation, and generalised sarcoma.
Epithelial - Papilloma of tongue, squamous cell carcinoma (SCC) of the oral cavity or gastric fundus,
pulmonary adenocarcinoma, hepatoma, adenomatous proliferation of the intrahepatic duct, SCC of the
cervix and vagina, adenocarcinoma of the oral cavity, squamous tumour of the stomach, thyroid
adenoma, and an early report of primary and metastatic lung tumours.
Other histogenesis - Melanoma of the oral cavity.
Collectively, the above observations and reports emphasise the broad range of neoplasms that occur in
captive macropodids. Apart from papillomas associated with poxvirus, however, neoplasms in free-
ranging macropods are apparently uncommon . Most of the above reports of neoplasms give diagnosis
but provide little detail on gross or microscopic findings – presumably because features typical of tumour
type – and therefore used to support diagnosis, were those found in comparable tumours in domestic
animals and man.
There are few reports of congenital and perhaps inherited disease in maropodids, and little information on
lesions present. Table 2 lists some reported conditions.
Table 2 - Some changes or diseases of congenital, genetic or suspected inherited origin, in
Australian macropodids
Species Change,
lesion or
Eastern grey
kangaroo & agile
Observed histologically within cervical
thymus of 11 animals. No associated
changes observed
Eastern grey
failure of
development of
premolars and
Aplasia of premolars & molars in right
mandible; presumed congenital. Left
mandible normal except for ‘lumpy jaw’
lesion – perhaps due to unilateral
mastication; Bacteroides sp, was isolated
Syndactyly in
manus of
pouch embryo
External examination revealed bilateral
lesions, with digits 3 and 4 conjoined partially
or completely on right and left sides,
Red kangaroo Multiple genital
Aplasia of penis, pouch and teats. Testes
status not ascertained, but assumed absent.
Animal had XX karyotype
Agile wallaby &
eastern grey
Intersex Various abnormalities involving penis, pouch,
teats and scrotum. Testes status not
ascertained but assumed present in wallaby
and absent in kangaroo. Karyotypes: wallaby
XXY; kangaroo XX
Red kangaroo,
tammar wallaby,
Intersex Variable presence, location and/or
development of pouch, mammary tissue,
scrotum and testes. Karyotypes of affected
animals included XO, XXY and XXY/XY/XX,
and XY
(a) Generalised nutritional excess or deficiency
In Western Australia, quokkas on Rottnest Island suffered severe starvation, weight loss and significant
mortality during the summer months. Illness and mortalities were associated with increased excretion of
Salmonella spp. considered to be related in turn to digestive physiology altered by poor quality feed during
Pathological changes in adult kangaroos and other macropods dying during drought are inadequately
studied but include lumpy jaw in red kangaroos, dehydration and cachexia, and a seasonal anaemia
associated with reduced protein in vegetation. Other morphological changes in drought affected red
kangaroos include decreased or increased size of the pituitary glands in adult males and females,
respectively, and in both sexes a decreased size of adrenal glands accompanied by cortical folding and
nodulation – with indications in females of continued stimulation of the zonae fasciculata and
glomerulosa, perhaps reflecting better adaptation. Nutritional deficit due to drought, especially if combined
with high environmental temperatures, has been shown by histology to cause testicular degeneration with
diminished fertility of red kangaroos in central Australia.
As well as the influence of quantity and quality of food offered to captive wildlife, the form in which it is
offered may also impact on health. Uroliths (composed of calcium oxalate and or phosphate) were found
in a range of captive marsupials including eastern grey kangaroos, and a red necked wallaby.
(b) Deficiency or excess of specific dietary components
Vitamin D - A deficiency of vitamin D may manifest as diminished provisional calcification of bone leading
to pathological fractures of bone as in rickets, with persistence of cartilage. Osteodystrophies due to
vitamin D
deficiency or calcium and phosphorus imbalance are not uncommon in orphaned pouch-young
marsupials and are generally seen as deformities of the thoracic cage.
Vitamin E - (but not necessarily selenium) responsive nutritional myopathy has been observed in a range
of macropods. Other disorders possibly linked to vitamin E include a deficiency-related steatitis in a
yellow-footed rock wallaby, and the development, in kangaroos given large doses of vitamin E, of scaly
yellow cutaneous plaques that eventually regress.
At necropsy, in animals with nutritional myopathy there is typically pallor and atrophy of pelvic and femoral
muscles which may have a spotted yellow-brown discoloration, or may, in severe cases, be firm, gritty
and friable. Other muscles such as those of the thorax and spine may also be affected.
Microscopically, changes in quokkas were especially apparent in pelvic muscles, and consisted of
degeneration and necrosis. Swelling of fibres was apparent in early stages and sarcolemmal nuclei were
pyknotic in some areas but plump and proliferating in adjacent viable zones. In older lesions
macrophages were filled with necrotic debris, and small numbers of polymorphonuclear neutrophils were
Sodium - Sodium deficiency was described in eastern grey kangaroos free-ranging in the Snowy
Mountains alpine region. Clinically, affected animals exhibited salt-hunger, and at necropsy the adrenal
glands were observed to be about double the weight of adrenal glands of ‘control animals from the sea
coast’. Microscopically, the zona glomerulosa was expanded, and the salivary glands of sodium deficient
kangaroos had a more extensive duct system. Also, cells lining the ducts were increased in height –
these salivary gland changes indicating chronic hyperactivity in active sodium resorption.
Lactose excess or intolerance - A dietary excess of lactose in hand-raised orphaned pouch-young
marsupials may be associated with diarrhoea or cataracts. Whether or not, and to what extent cataract
formation in a range of marsupials is due to primary or acquired deficiencies of galactokinase and
transferase has yet to be resolved. Although the cause is not understood, cataracts appear to be more
common in joeys fed milk which contains lactose. Cataracts – many considered to be of nutritional origin
– have been described in a range of captive orphaned macropods, as well as wild swamp wallabies. In
marsupials, cataracts considered due to enzyme deficiency are bilateral. Clinically, opacities may be
associated with a disordered gait and disorientation consistent with visual deficit. With mature cataracts
the suspensory lens ligaments are weak so that prolapse of the lens readily occurs – rendering surgery
‘almost impossible’. Glaucoma is a frequent sequel to prolapse. Also, in such cases the primary vitreous
may also be opaque.
(c) Metabolic diseases
Diabetes has been induced in the red kangaroo by chemical destruction of the islets of Langerhans.
Affected animals showed negative nitrogen balance and hyperglycaemia, and became inco-ordinated and
comatose. Insulin restored normal metabolism.
Renal failure associated with severe, fatal nephrocalcinosis in the endangered Gilbert’s potoroo is
described in Western Australia. It was suggested that the cause may be an inherited metabolic defect.
Capture myopathy
Although seen in many wild species including birds, capture-, or so-called exertional myopathy in
Australia – sometimes due to trapping – is mostly diagnosed in macropods.
The cause of capture myopathy is debated and the disorder needs to be differentiated – largely on the
basis of history – from nutritional muscular dystrophy. Signs are usually apparent one to two weeks post-
capture with deaths occurring anytime up to four weeks post-capture.
Signs include stiffness, pain and spasm of muscle groups especially in the cervical region, torticollis,
partial paralysis of the limbs, posterior paralysis and prostration. Respiration is laboured and heart rate
increased. Myoglobinuria may be present. Sometimes animals die suddenly from acute heart failure
without any premonitory signs.
Macroscopically, muscle lesions occur principally in the limbs. In macropods, the neck muscles are
frequently involved, as are muscles of the back. Lesions are bilateral but not necessarily symmetrical.
Affected areas are well delineated, softer than normal and are slightly pale to light grey-brown with
occasional haemorrhage. Similar lesions may be found in myocardium. The earliest muscle lesions are
detectable 1-2 hours post-capture. At 10 hours the affected muscles are dark red and dry and may
appear as streaks or involve the whole muscle. At 3-4 days lesions become paler, soft and gelatinous.
After one or more weeks there is increasing fibrosis and affected muscles become white and firm.
Microscopically, in the early stages there is loss of cross striation of muscle, hyaline eosinophilia and
development of contraction bands and myofibre fragmentation, sometimes with mineralisation of
mitochondria. Later an inflammatory infiltration of neutrophils and macrophages occurs and in more
advanced lesions macrophages and proliferating sarcolemma predominate. Fibrosis and mineralisation
of necrotic fibres may also be observed. Microscopic lesions in other tissues may include myoglobinuric
nephrosis with the presence of casts, pulmonary oedema and congestion, periacinar hepatic necrosis
due to anoxia, lympholysis, pulmonary congestion and oedema if the myocardium is affected,
perivascular haemorrhages in the brain and meninges, and sometimes haemorrhage and necrosis in the
adrenal cortex.
Inter-specific trauma and predation
In addition to those injuries inflicted by man as the major predator, lesions attributed to native or
introduced predators are described in many Australian native mammals.
Necropsy examination of mostly juvenile red kangaroos attacked by dingoes revealed animals were in the
majority of cases found in right lateral recumbency, usually with the head slightly thrown back. Unless the
carcass had been eaten, signs of injury were unusual although occasionally fur at the throat was slightly
blood-tinged. Examination of the skinned carcass, however, presented a ‘very different picture’, as
extensive bite wounds were always present over the neck and thorax, or throat. These lesions were deep
penetrating and accompanied by subcutaneous and intramuscular haemorrhage, and oedema.
Penetration often extended to major organs of the thorax, sometimes the abdomen also, and was
accompanied by fractures of bones such as ribs, scapula and vertebrae. Bite wounds were also common
in muscles of the left hindquarter. Similar internal and external lesions were observed in captive juvenile
macropods attacked by dogs.
Motor vehicle induced trauma
There appear to be no published analyses of lesions induced in macropods by motor vehicle accidents.
A five year study of road-kills of eastern grey kangaroos and swamp wallabies on a highway in Victoria,
however, revealed that the majority of kills were of adult males, and interestingly, that most road-kills
occurred around the time of full moon, suggesting that kangaroos are more mobile during that phase.
Drowning was confirmed or suspected as the ultimate cause of death of wild kangaroos that were blind
as a consequence of orbivirus infection. Gross and or microscopic changes in these cases variously
included marked pulmonary oedema with froth-filled airways, emphysema and atelectasis, and diatoms
present in affected lung tissue. Presumably, as in other species the possible occurrence of so-called ‘dry
drowning’ – in which no fluid is present in airways – needs to be kept in mind.
Gunshot and foreign body injury
Gunshot wounds are recorded in macropods including a red-legged pademelon joey with multiple pellets
in several sites, and an adult eastern grey kangaroo with streptococcal osteomyelitis for which the initial
injury was considered, on the basis of radiography, to have been fracture of mid-shaft radius and ulna by
penetration of tissue by a high velocity projectile. Such projectiles are normally copper jacketed with a
small soft lead point. It was suggested that on striking the area the force of impact would have fractured
the bones then passed through interosseous space leaving very small scattered flakes of lead as
observed in this case. In contrast, in gunshot injuries caused by low velocity projectiles, larger lead
particles are observed.
Foreign bodies, especially string, are common causes of intestinal problems in pet macropods.
Excessive cold or heat
Hairless pouch-young marsupials may be regarded as being largely poikilothermic so that in macropod
joeys both hyperthermia (body temperature > 38
C), and hypothermia (body temperature < 35
C), may
occur with inappropriate housing or handling.
Gross changes observed in an agile wallaby joey that died of heat stroke included petechiae and
ecchymoses in both cardiac ventricles, marked congestion of the lungs, and apparent cerebral oedema
such that the sulci of the cerebral hemispheres were less obvious than normal and the gyri protruded
through cranial incisions during dissection. Microscopic examination confirmed cardiac haemorrhages in
endocardium, myocardium and epicardium, and haemorrhages were also seen in many other tissues
including stomach and intestines, kidney, adrenal, thymus, and cerebellum. Vascular congestion was
apparent in all organs. Other changes included multifocal myocardial necrosis, occasional necrotic foci in
the liver, and brain lesions such as oedema, and loss of Purkinje cells.
Together with drought, high environmental temperatures were shown to cause testicular degeneration in
wild red kangaroos in central Australia. With chronic degeneration in some aged males – presumably the
combined result of repeated hot weather and nutritional deficit – the testes were brownish, and smaller
than normal. Microscopically, spermatogenesis was in abeyance in some seminiferous tubules in these
animals; testicular stroma was comparable to that in younger (but nevertheless mature) animals.
In the testes of kangaroos sampled in summer, impaired spermatogenesis was manifested by reduced
diameter of tubules with vacuolation and lack of germinal epithelium, the presence of large multinucleate
cells, and cellular debris within the lumens of tubules and the efferent ducts. Quantitative histological
studies of the testes of these animals also revealed differences in the interstitium, especially in relation to
drought. In times of dietary abundance the amount of interstitium was greater, and the size of Leydig cells
was larger than during drought. This latter finding is perhaps at variance with chronic testicular
degeneration in domestic animal species – in which the interstitium/tubule ratio is increased as fibrous
tissue replaces damaged tubules.
Skin and subcutis
Calcinosis circumscripta in a scrub (swamp) wallaby presented as chronic proliferative lesions on the
plantar aspect of the feet between toes. The calcified area, which contained occasional bone-like
spicules, was surrounded by a fibrous capsule.
Hypertrophic osteopathy (HO), so-called Marie’s disease, is described in a red kangaroo and a
common wallaroo. The kangaroo was presented for examination because of lameness. There was bony
thickening of all limbs due to periosteal new bone growth. There was no evidence of respiratory signs,
and no cough was elicited, but 25 ml of pus – from which mixed coliforms were isolated – was aspirated
from the thorax. Treatment with antibiotics was commenced, and within 6 weeks the lameness had
resolved. The wallaroo was presented for examination with swelling of the forefeet. Clinical examination
revealed thickening of the radius and ulna with taut overlying skin. A presumptive diagnosis of HO was
made. Subsequent necropsy findings included multiple caseous foci throughout the lungs associated with
haemorrhage, consolidation, pleural adhesions and emphysema.
Unilateral failure of development of mandibular cheek teeth has been reported in a wild eastern grey
kangaroo found dead. Premolars and molars were absent in one mandible, and there was corresponding
lack of wear and abnormal elongation of the maxillary cheek teeth on the affected side. It was concluded
that molar aplasia was congenital, and that an associated lumpy jaw lesion on the contralateral mandible
may have been related to abnormal mastication. Maxillary molar progression, which is affected by
abrasion, also seemed retarded on the affected side. Death was related to malnutrition, perhaps
associated with the oral lesions, and a heavy parasite burden.
Barber, D., J. Campbell, T. Luke et al. 2008. Unilateral failure of development of mandibular
premolars in an eastern grey kangaroo (Macropeus giganteus) and its effects on molar
progression. Australian Veterinary Journal 86: 64-66.
Pronounced amyloidosis of unknown cause was observed in the liver of an eastern grey kangaroo. The
liver was examined histologically because subcapsular haematomas approximately 10 cm in diameter
were observed grossly.
An ‘enigmatic’ hepatopathy of unknown but presumed parasitic cause was described in brush-tailed
bettongs but apparently not in other marsupial species that were simultaneously housed in the same
pens. Grossly, 12 animals had hepatomegaly characterised by large circular nodular lesions with dense
fibrosis and variable calcification affecting one or more lobes. These lesions occupied up to half of the
hepatic parenchyma.
Microscopically, in all but one case lesions were massive, and except in two cases all lesions were
chronic. In these latter cases focal areas of hypercellularity consisted mainly of plasma cells, histiocytes,
fibrocytes, lymphoid cells and occasional multinucleated giant cells. Centrally within these areas were the
enigmatic, presumed parasitic bodies, some of which were surrounded by a rim of necrosis.
Circulatory system
Medial sclerosis and arterial calcification were observed in more than 10% of 313 captive macropods,
and these lesions showed considerable resemblance to those seen in humans and related to age.
Although in this study the aetiology remained cryptic, a dietary cause was suspected – with cessation of
the condition once diet was changed. Many species, but especially agile wallabies, were affected.
Grossly there was much variation although the aorta was consistently involved and had more severe
changes than in other arteries. On cutting, the lesions were firm and gritty and affected vessels had little
or no elasticity. Microscopically, lesions frequently presented as small foci or were linear along the long
axis of the aorta. In some cases there was necrosis of smooth muscle and elastica.
Lesions suggestive of hypertension of unknown aetiology were evident in many adult western grey
kangaroos from a single zoo in the USA. Clinical signs included vague nervous system deficits and
blindness in a subset of affected animals. Thickening and hypertrophy of the media, and increased
tortuosity of renal arterioles was characteristic.
Kagan, R.A., M. Kinsell, K. Gloor et al. 2009. Morphologic evidence suggestive of hypertension in
western grey kangaroos (Macropus fuliginosus). Veterinary Pathology 46: 977-984.
Urinary system
Although considered likely to be an inherited metabolic disease, renal oxalosis in the endangered
Gilbert’s potoroo is of uncertain causation. Clinically, glycolate in the urine of affected animals was
greatly elevated. At necropsy, on removal of the capsule and on the cut surface the kidneys were rough
and irregular, and microscopically – in animals that died – there were massive oxalate deposits present in
renal tubules.
In a histological study of kidneys from 169 macropods of 16 species, intranuclear inclusions of
unknown cause, but apparently of no clinical significance, were found in 9 animals from four species.
Inclusions were seen only in captive animals, and were not found in joeys or adolescents. The inclusions,
which were in the nuclei of proximal convoluted tubule cells of the renal cortex, were homogenous,
eosinophilic, oval to spherical, and associated with margination of nuclear chromatin. Inclusions were
approximately 5 µm in diameter and occupied about 75% of the nuclear area. Usually a single inclusion
was present but occasionally two smaller inclusions were seen. Often all nuclei in affected tubules had
inclusions while adjacent tubules had none. Histochemical examination of sections from an affected
black-striped wallaby revealed that inclusions did not stain with Ziehl-Neelsen, von Kossa or PAS
techniques. On electron microscopic examination the inclusions were seen to be homogenously electron-
dense. Viral particles or crystals were not seen.
Similar inclusions were observed in a bridled nailtail wallaby examined at the Australian Registry for
Wildlife Health.
Cited early reports of urolithiasis, presumably of undetermined cause, in captive macropods include a
calculus obstructing the neck of the urinary bladder in a red kangaroo, and renal calculi – one of which
contained uric acid – in two wallabies. Bilateral renal calculi in a (presumed Tasmanian) pademelon
measured 5mm x 5 mm, were yellow-grey and granular, and associated with pyelonephritis. They were
composed mostly of an acidic, nitrogenous, phenolic compound.
Calculi composed of magnesium hydrogen phosphate are also reported in a captive young eastern grey
kangaroo that was presented for examination because of dysuria. The animal’s diet was quite varied and
included dried cat food. Physical examination revealed gross distension of the bladder, and a 2 mm
diameter calculus was found at the tip of the penile urethra. The animal died during attempts to pass a
catheter and necropsy revealed two additional calculi 2 cm x 1 cm in the pelvic urethra. Associated
changes included suppurative urethritis, periureteritis and bilateral pyelonephritis. Cause and
pathogenesis of urolithiasis in this animal were not ascertained but dietary factors may have been
Multisystemic disease
Lysosomal storage disease was suspected as the cause of illness in separate, young, eastern grey-,
and red kangaroos. Cause of the lesions was not confirmed but possibilities included congenital disease
or plant toxicosis. History, signs and gross findings in the two cases varied, but microscopically, in both
cases the significant change was the widespread presence of foamy vacuolated macrophages, the
contents of which was PAS positive.
A somewhat similar storage disorder was observed in a captive parma wallaby that showed neurological
signs of sudden onset and was euthanased. No gross lesions were described but microscopically
abundant brown, granular pigment – considered to be lipofuscin – was present in nerve cell bodies in
grey matter of the brain and spinal cord. Suggested aetiologies were inherited lipofuscinosis and plant
toxicosis, but in view of the history of similar clinical signs occurring in other wallabies confined to one
enclosure, the latter possibility was preferred.
Original Acknowledgements: I am grateful to colleagues who kindly provided many of the images used
in my presentation, and to Dr Larry Vogelnest for perusal of these notes prior to submission.
ResearchGate has not been able to resolve any citations for this publication.
ResearchGate has not been able to resolve any references for this publication.