Hematological, Macroscopic and Microscopic Findings in Two Stranded Whales (Mesoplodon densirostris and Kogia sima) and Possible Causes of Deaths

Abstract

Stranded marine mammals may serve as opportunities for probing scientific queries. This study subjected formalin-fixed tissues of two cetaceans, Mesoplodon densirostris (Blainville’s beaked whale) and Kogia sima (dwarf sperm whale), found stranded in Region 11 (Davao) of the Philippines between April and July 2014 to histopathological analyses following necropsy and hematological evaluations. Lesions observed in 2 of 2 animals (100%) were congested hepatic sinusoids, hemorrhages, hemosiderosis, parasitic disease, and pulmonary edema. Other lesions (1 of 2, 50%) were seen in the (1) gastrointestinal tract (congestion, Lieberkhun mononuclear cell infiltrations, villi blunting and adhesion), (2) kidney (blood sludging, membranous glomerulopathy, tubular cell atrophy), and (3) lungs (fungal granuloma, pneumonia). M. densirostris showed severe iron deficiency and thrombocytopenia but with lymphocytosis. K. sima revealed low white blood cell count and neutropenia but with thrombocytosis and hemoconcentration. This study suggests that systemic infection for both animals with (1) membranous glomerulopathy and endoparasitism-associated pneumonia (in M. densirostris) and (2) microthrombi formation (in K. sima) were the major causes of their deaths. Presented results, however limited, may serve as baseline data underpinning cetacean clinicopathological research in the Philippines.

Full text

Hematological, Macroscopic and Microscopic Findings in Two Stranded Whales
(Mesoplodon densirostris and Kogia sima) and Possible Causes of Deaths
Jonah L. Bondoc, MS EnvSc, RCh1,2*, Lemnuel V. Aragones, MS MarSc., PhD1 and
Joseph S. Masangkay, DVM, MAgr, DAgrSc3
1Marine Mammal Research and Stranding Laboratory, Institute of Environmental Science
and Meteorology; 2Research and Analytical Services Laboratory, Natural Sciences Research
Institute, University of the Philippines, Diliman, Quezon City, Philippines; 3Department
of Veterinary Paraclinical Sciences, College of Veterinary Medicine, University
of the Philippines, Los Baños College, Laguna, Philippines
Philipp. J. Vet. Med., 54(1): 63-69, 2017
*FOR CORRESPONDENCE:
(email: jlbondoc@yahoo.com)
CASE REPORT
ABSTRACT
Stranded marine mammals may serve as opportunities for probing scientic
queries. This study subjected formalin-xed tissues of two cetaceans, Mesoplodon
densirostris (Blainville’s beaked whale) and Kogia sima (dwarf sperm whale),
found stranded in Region 11 (Davao) of the Philippines between April and
July 2014 to histopathological analyses following necropsy and hematological
evaluations. Lesions observed in 2 of 2 animals (100%) were congested hepatic
sinusoids, hemorrhages, hemosiderosis, parasitic disease, and pulmonary edema.
Other lesions (1 of 2, 50%) were seen in the (1) gastrointestinal tract (congestion,
Lieberkhun mononuclear cell inltrations, villi blunting and adhesion), (2) kidney
(blood sludging, membranous glomerulopathy, tubular cell atrophy), and (3) lungs
(fungal granuloma, pneumonia). M. densirostris showed severe iron deciency
and thrombocytopenia but with lymphocytosis. K. sima revealed low white blood
cell count and neutropenia but with thrombocytosis and hemoconcentration.
This study suggests that systemic infection for both animals with (1) membranous
glomerulopathy and endoparasitism-associated pneumonia (in M. densirostris)
and (2) microthrombi formation (in K. sima) were the major causes of their deaths.
Presented results, however limited, may serve as baseline data underpinning
cetacean clinicopathological research in the Philippines.
Key words: hematology, histopathology, Kogia sima, Mesoplodon densirostris, necropsy
2011). Implicit to this, any disorder detected in
marine mammals can serve as early warnings
to other aquatic species, environment and
human health - ‘One Health’ concept (Atlas and
Maloy, 2014). Therefore, when an individual or
a group of marine mammals are found aground,
ecological risks and human health threats may
be increasing (Bossart, 2011). More so, marine
mammal stranding events are now occurring
on a global scale (Geraci and Lounsbury, 2005;
Aragones et al., 2010).
The Philippines harbors a diverse
assemblage of 29 marine mammal species (28
INTRODUCTION
63
Marine mammals are among the animals
that occupy the top trophic levels in marine
habitats. Being top consumers of production,
their abundance and distribution play
important roles in the function and structure
of aquatic ecosystems (Baum and Worm, 2009).
Furthermore, their large fat reserves (blubber),
which can serve as contaminant depots, and
long life spans make them one of the best
sentinels of the aquatic environment (Bossart,

BONDOC, ARAGONES AND MASANGKAY
cetaceans and the dugong (Dugong dugon)
(Aragones et al., 2017). Twenty-seven of the
29 conrmed species were recorded to strand
with an average of 59 events per year from
2005-2016 data (Aragones et al., 2017). A high
preponderance during the Northeast monsoon
in regions with coastline including 64 coastal
provinces were documented by the authors.
Among the most frequent cetaceans to strand
included whales, e.g. Kogia sima (n=36) from
a total of 713 events (2005-2016) (Aragones
et al., 2017). Pertinent tissue samples can be
obtained from these events, albeit logistic
impediments, to elucidate gaps in marine
mammal science. While Philippine studies on
stranded cetaceans had previously investigated
their ecology (Aragones et al., 2010; Aragones
et al., 2017), microbiology (Torno et al., 2008;
Obusan et al., 2015), and impacts of human
interaction (Obusan et al., 2016), no data from
clinical pathophysiologic investigation have
been reported to date. Thus, it was decided
to initiate a preliminary study aimed at
elucidating hematological, histopathological,
and necropsy data and their association to the
deaths of two whales, Mesoplodon densirostris
(Blainville’s beaked whale) and K. sima (dwarf
sperm whale), found stranded in Davao (Region
XI) in 2014. The Davao region is one of the
regions in the Philippines with diverse marine
mammal assemblage (Aragones et al., 2017).
CASE PRESENTATION
Region XI’s Bureau of Fisheries and
Aquatic Resources (BFAR) Ofce and the
Philippine Marine Mammal Stranding
Network (PMMSN) provided the stranding
reports for both whales. The PMMSN has a
MOA with BFAR 11 to respond to strandings.
Case 1 involved an adult male M.
densirostris measuring 3.66 meters (Fig. 1).
A sherman reported this individual animal
swimming weakly near the shallow waters of
Barangay 76-A, Bucana Boulevard, Davao City
(7°03’32.1”N 125°36’51.9”E) on 15 April 2014,
0900 hours. The whale was released back to
deeper waters four hours after stranding.
Unfortunately, the animal re-stranded and was
observed swimming on its side while breathing
heavily prior to death.
Case 2 was a pregnant but emaciated
K. sima measuring 2.15 meters (Fig. 2). The
animal was found alive by a local resident on the
sand adjacent to Jones Beach Resort, Barangay
Talomo, Davao City (7°2’37”N 125°32’34”E)
on 23 July 2014, 0130 hours. Supportive care
was provided but it succumbed after almost 15
hours under rehabilitation.
Blood sampling and hematologic proling
were performed in Davao City. Complete blood
count (CBC) results received from the local
veterinarian were compared with published
hematologic prole of clinically healthy captive
and free-ranging cetaceans (see Table) (Fair et
al., 2006). Post-mortem examinations, carcass
putrefaction evaluation and histopathological
procedures were conducted following Geraci
and Lounsbury (2005). Processing of tissue
samples was done at the College of Veterinary
Medicine (CVM), University of the Philippines
Los Baňos (UPLB), Laguna. Carcass condition
for both cases were categorized as Code 2 (i.e.
freshly dead) following Geraci and Lounsbury
(2005).
Blood examination of Case 1 revealed
low white blood cell (WBC) count and
thrombocytopenia but with lymphocytosis
(see Table). Results also showed elevated
erythrocyte sedimentation rate (ESR). Gross
external examination of this cetacean showed
several wounds located ventrally. Upon
necropsy, presence of foreign bodies (broken
pieces of polyvinyl chloride (PVC) pipes) in
the main stomach were recorded. The gastro-
intestinal system showed varying degrees of
congestion and hemorrhages with blunting and
adhesion of the intestinal villi (Fig. 3). Presence
of considerable number of mononuclear cells in
the crypts of Lieberkuhn with inammation
within lamina propria and the epithelium
(Fig. 4) were observed upon histopathological
evaluation. Furthermore, a renal lesion with
markedly thickened capillary walls, with
associated thickening of the Bowman’s capsule
(Fig. 5) was observed. This beaked whale
had no observed lung lesion during necropsy.
However, histopathology showed a clear lesion
of pneumonia and pulmonary edema with
concomitant parasitism (Fig. 6). Furthermore,
immature roundworm (larvae) were seen
deeply embedded in the pulmonary tissue.
Hematologic results of Case 2
64

revealed low WBC and neutropenia but with
thrombocytosis and hemoconcentration (see
Table). This K. sima, with two circular wounds
posterior to the right eye, had prominent
peanut-shaped rostral area. Numerous
wounds were also recorded in the animal’s
body. Among the most signicant observation
was the apparent presence of hemorrhage
FINDINGS IN TWO STRANDED WHALES 65
Fig. 1. An adult male M. densirostris. Fig. 2. An adult female K. sima with prominent circular
wounds (cookie-cutter shark bites) (arrows) and peanut-shaped rostral area indicating low
body condition score. Fig.s 3-6. M. densirostris. Fig. 3. Intestine. Varying degrees of congestion
with blunting and adhesion which lessened the surface area of the intestinal mucosa. Fig. 4.
Intestine. Mononuclear cells in the crypts of Lieberkuhn indicative of enteritis. Inammatory
cells within lamina propria and the epithelium are evident. H&E, 100µm. Fig. 5. Kidney.
Endothelial deposits indicate secondary membranous glomerulopathy with Bowman’s
capsule thickening. H&E, 100µm. Fig. 6. Lung. Lesion of pneumonia and pulmonary edema
with concomitant parasitism. Immature roundworm larvae sections (arrows) embedded in
bronchial/bronchiolar remnants with neutrophils and eosinophils. H&E, 200µm.

from the external genital and rectal area (Fig.
7). Foreign bodies (plastic material) were
also ingested by this animal. Parasites in the
stomach were observed (Fig. 8), most likely
nematodes (roundworms), a frequent nding
in the gastro-intestinal tract of juveniles and
adult cetaceans after consuming infected prey
(Domiciano et al., 2016). The uterus was seen
to have a fetus measuring two inches in length.
Multifocal hard nodules in the lung and pointed
apex of the liver with some form of adhesion
were also observed. Blood sludging was evident
in the severe congestion in the kidney, with
beginning signs of microthrombi formation (Fig.
9). Presence of plenty of hemosiderin granules
in the liver was observed. A big portion of the
lung contained the fungal granuloma lesion
with pulmonary edema (Fig. 10).
DISCUSSION
Each hematologic abnormality observed
in these two cases has been reported to have
occurred in other stranded marine mammals
(e.g. Sampson et al., 2012) but none of these
combinations. These changes in the blood
proles are known indicators of infection in
cetaceans (e.g. Fair et al., 2006) predisposed
by condition such as chronic disease, poor
nutritional status and even pregnancy (like
Case 2 of this paper) (Hohn et al., 2006).
Deviation from the standard hematologic
references have also been described as a
stress response in cetaceans most likely to an
inammatory attack (Sampson et al., 2012).
Pica appetite was evident in Case 1 by
the ingestion of foreign bodies that may have
caused the varying degrees of congestion and
BONDOC, ARAGONES AND MASANGKAY
66
Figs. 7-10. K. sima. Fig. 7. Uro-genital. Apparent presence of hemorrhage. Fig. 8. Stomach.
Presence of roundworms (circle) embedded in the mucosa. Fig. 9. Kidney. Glomerular
endothelium damage and severe congestion showing signs of microthrombi formation
compromising blood ow in the microvasculature of the kidney. Fig. 10. Lung. Multifocal
collection of inammatory cells demonstrating lesions of fungal granuloma (arrows) and
pulmonary edema, including activated macrophages (epithelioid cells). H&E, 200µm.

FINDINGS IN TWO STRANDED WHALES 67
hemorrhages in the gastro-intestinal tract
(Simmonds 2012). Blunting and adhesion of
its intestinal villi lessened the surface area
of the intestinal mucosa which compromised
the nutritive absorptive capacity of the animal
identical to a report on mice by Erben et al.
(2014). An indication of enteritis was based
on the presence of mononuclear cells in the
crypts of Lieberkuhn, resembling an avian
case (Sivaseelan et al., 2013). Salmonella spp.
bacteria, which are common pathogens in
cetaceans, are the causative factors in cetacean
enteritis (e.g. Jepson et al., 2000). The presence
of subendothelial dense deposits, seen on the
kidney, was a type of secondary membranous
glomerulopathy associated with systemic
autoimmune disease and inammatory insult
leading to infection (Hohn et al., 2006). The
clear lesion of pneumonia and pulmonary
edema with concomitant parasitism lessened
the respiratory capacity of the animal which
could have explained the attempt of the whale
to return to the shallow part of the sea to
avoid drowning (Domiciano et al., 2016). The
roundworm larvae found in the pulmonary
tissue were most likely lungworm whose
mode of transmission was via infected prey
(Measures, 2001). The lungworm remained
unconrmed in this study.
The two prominent circular wounds
of Case 2 were suggestive of cookie-cutter
shark (Isistius brasiliensis) bites (Fig. 2). The
animal’s peanut-shaped rostral area indicated
low or poor body condition score (Joblon
et al., 2014). The roundworms observed in
the stomach were most likely nematodes,
a frequent nding in the gastro-intestinal
tract of juveniles and adult cetaceans after
consuming infected prey (e.g. Domiciano et
al., 2016). This was not considered a threat
since the animal did not show any host-tissue
reaction. Like the previous case, the species
of the parasite remained unconrmed. The
presence of loads of hemosiderin granules in its
liver was a result of red blood cell destruction,
like those reported on sh and seabirds (Khan
and Nag, 1993). This destruction that led to
hypoproteinemia resulted to the depletion
of the uid part of the blood resulting to low
WBC count and hemoconcentration (Stockham
and Scott, 2013). The severe renal congestion
and microthrombi formation seen in this case
have been reported to frequently develop into
Disseminated Intravascular Coagulation
(DIC) and death due to multiple organ failure
in mammals (e.g. Stockham and Scott, 2013).
The observation of apparent bleeding in the
urogenital region was not hemorrhage but a
Table. Hematologic results for M. densirostris and K. sima that stranded in Davao City.
NR = no record.
*From healthy captive and free-ranging cetaceans.

defensive secretion method, inherent to kogiids,
to escape from bigger predators just like the
ejection of ink by the squid (Fire et al., 2009).
This is a common misperception since kogiids
are very atypical species (i.e. that exhibit such
defensive mechanism). On the other hand, the
fungal granuloma lesion in the lung might
have caused difculty in breathing, consistent
with the results of a previous report on small
cetaceans found stranded in Brazil (Domiciano
et al., 2016). Most granulomas, according
to Domiciano and his colleagues (2016), are
caused by fungal infection, a condition regularly
encountered and associated with cetaceans
with poor chance of survival. The numerous
wounds observed in this animal might have
served as entry points to fungi invasion. This
led to an inammatory response in the animal
causing the immune cells to migrate from the
dermal papillae to the site of infection causing
cyst or granuloma formation (Mouton and
Botha, 2012).
In conclusion, the clinicopathological
results of this study suggest that systemic
infection together with secondary membranous
glomerulopathy with endoparasitism-
associated pneumonia was most likely the
major causative factors to the death of a M.
densirostris (Case 1). Systemic infection may
have debilitated a K. sima (Case 2), and in
combination with microthrombi formation,
may have evoked the animal to its death.
It should be noted, however, that it was not
possible to rule out a single disease as the
primary cause of the demise of the animals as
other underlying diseases could exist.
To the authors’ knowledge, this is the
rst report of (1) severe iron deciency and
thrombocytopenia but with lymphocytosis in
M. densirostris, and (2) neutropenia but with
thrombocytosis and hemoconcentration in K.
sima, with their associated histopathologies.
While the present report involved only two
animals, possible prognostic use of correlating
histopathologic ndings with hematologic
data in assessing cetacean stranding events,
supported by standardized post-mortem
examination methods, is now evident for the
Philippines.
ACKNOWLEDGMENT
The authors acknowledge Dr. Elaine Vera
M. Belvis (BFAR Region 11), who was the lead
veterinarian in these two stranding cases and
for sending the tissues, Ms. Raquel O. Rubio
(Biological Research and Service Laboratory,
Natural Sciences Research Institute UP
Diliman) for allowing the use of the trinocular
microscope, Mr. Maurell M. Navasero (CVM,
UPLB) for assisting in the processing of the
samples, and the Natural Sciences Research
Institute UP Diliman nancial support for this
research.
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