Progress of the international work of the "Imidacloprid Flea Susceptibility Monitoring Team".

Abstract

The "Imidacloprid Flea Susceptibility Monitoring Team" has aim to develop and validate a bioassay to effectively monitor and document susceptibility of cat flea (Ctenocephalides felis) isolates to imidacloprid. A larval bioassay was developed, standardized and validated and agreed upon by the team as the reference diagnostic test kit as research has shown that the proposed WHO adult test was not reliable. The selected 3 ppm discriminating dose, determined from evaluating year 2000 field isolates, was approximately 2 times the highest LC95 of the control laboratory flea strains. In 2001 and 2002, this standardized bioassay was used to test more than 190 separate egg collections from individual flea isolates from USA, UK and Germany. If survivorship in the 3 ppm assay is confirmed, the LD50 values of this isolate and the laboratory strains will be determined by a dose-response study in the range of 0.005 to 3 ppm imidacloprid. By comparison of these LD50 values it can be estimated whether a shift in susceptibility to imidacloprid has occurred. In either case the flea isolate will be researched extensively. Currently an in-vivo test which will evaluate the on-host efficacy of Advantage is being established. None of the to date tested isolates revealed reduced susceptibility to imidacloprid.

Full text

Page 1

Focus on Parasitolog y
– 2nd E dition –
C ontribution of B ayer Animal Health at the
19thInternational C onferenc e of the W AAVP
Aug ust 10 – 14, 2003 · New Orleans, US A

Page 2

Page 3

Foc us on P arasitolog y
C ontribution of B ayer Animal Health
at the 19thInternational C onferenc e
of the W AAVP
Aug ust 10 – 14, 2003 – New Orleans, US A
B ayer S ymposium
B ayer Animal Health – P ets, P arasites and P roduc t S olutions
S c ientific P rog ramme

Page 4

P R E FAC E
The 19thInternational Conference of the World Association for the Advancement of
Veterinary Parasitology takes place in the city of New Orleans. As Chair of the
local organizing committee,
I am looking forward to a five-day conference with scientific stimulation and
social interaction.
Like most of biological science, the field of Veterinary Parasitology is undergoing
major advances because of the growth in molecular genetics and cell biology. At
the same time, many of our concerns and questions regarding our understanding of
parasites, their host interactions and their control remain unchanged. The theme
of the conference, “Old Dreams – New Visions:
Veterinary Parasitology in the 21stCentury”, was designed to stimulate
discussion of the merging of new technologies with traditional studies to answer
persistent as well as new questions.
The program includes plenary lectures, symposia, round table discussions and oral
as well as poster presentations. Organizing a world congress like this would not be
possible without the support
of the sponsors. Bayer Animal Health, a parasitology-focused company, is a major
sponsor of this year’s WAAVP conference and will present papers of various
parasitological topics.
The presentations cover a wide variety of research fields in protozoology,
helminthology and on ectoparasites. All presentations, whether oral or poster
presentations, are combined in this supplement to ‘Parasitology Research’ titled
“Focus on Parasitology”. The proceedings, together
with this supplement, will remain as a reference document from this year’s
WAAVP congress for years to come.
I would like to welcome you all to the WAAVP conference and the city of New
Orleans, the city
of plenty – Creole and Cajun cuisine, music like blues, jazz, rock and roll to name a

Page 5

INTR ODUC TION
B ayer Animal Health
“Foc us on P arasitolog y”
– 2nd E dition –
Bayer Animal Health business group is proud to participate – as in previous years
– in the 19thInternational Conference of the World Association for the
Advancement of Veterinary Parasitology (WAAVP) 2003, in New Orleans,
Louisiana, USA. Parasites continue to have an important impact on the well being
of animals as well as human health and thus an effect on economic growth
throughout the world. Diseases caused by parasites remain a major threat to
farm, as well as pet animals and thus research and development of products in the
field of veterinary parasitology is an important segment within the Animal Health
industry. The total Animal Health market in the year 2002 was estimated at 14.0
billion Euro of which parasiticides were the largest market segment with 27% or
3.8 billion Euro. Bayer Animal Health business group is committed to supporting
parasitology research to ensure constant improvement in existing therapeutics
and the development of innovative remedies. In the ongoing battle against parasitic
infections the veterinary profession, we believe, plays an important role in both
the education and implementation of preventative care for producers as well as pet
owners. Pet owners especially rely upon the expertise and advice given by
veterinarians. Veterinarians are uniquely suited to the role of educating the public
about the hazards of zoonotic diseases. The theme of this year’s WAAVP
conference: “Old Dreams – New Visions: Veterinary Parasitology in the 21st
century” expresses clearly where we stand with our discipline.
We within Bayer Animal Health are proud to participate in this years meeting with
a total of 25 presentations from all fields of parasitology: ectoparasites,
helminths and protozoa, all combined in this brochure “Focus on Parasitology”, a
supplement to Parasitology Research one of the leading international parasitology
journals.
We hope you enjoy the conference, gain new scientific information, refresh old
friendships, make new friends and enjoy the city of New Orleans.
Norbert Mencke, DVM, PhD
Bayer AG

Page 6

C ONTE NT
B aye r S ympos ium
B ayer Animal Health – P ets, P arasites & P roduc t S olutions
Evaluation of Permethrin and Imidacloprid for Prevention of Borrelia burgdorferi
Transmission from Blacklegged Ticks (Ixodes scapularis) t o Borrelia burgdorferi-free Dogs
Spencer J.A., Butler J.M., Stafford K.C., Pough M.B., Levy S.A., Bledsoe D.L. & Blagburn B.L.
105
Repellent Efficacy of a Combination Containing Imidacloprid and Permethrin
against Sand Flies (Phlebotomus papatasi) on Dogs
Mencke N., Volf P., Volfova V. & Stanneck D.
107
Evaluation of the Efficacy of an Imidacloprid 10% / Moxidectin 1% Spot-on
against Otodectes cynotis in Cats
Fourie L.J., Kok D.J. & Heine J.
111
Larvicidal and Persistent Efficacy of an Imidacloprid and Moxidectin
Topical Formulation against Endoparasites in Cats and Dogs
Samson-Himmelstjerna G. von, Epe C., Schimmel A. & Heine J.
113
S c ie ntific P rog ramme
Evaluation of K9 Advantix™ vs. Frontline Plus® Topical Treatments to Repel
Brown Dog Ticks (Rhipicephalus sanguineus) on Dogs
Young D.R., Arther R.G. & Davis W.L.
115
The Effects of an Imidacloprid and Permethrin Combination against Developmental Stages of Ixodes
ricinus Ticks
Mehlhorn H., Schmahl G., Mencke N. & Bach T.
118
Efficacy of the Compound Preparation Imidacloprid 10% / Permethrin 50% Spot-on against Ticks
(I. ricinus, R. sanguineus) and Fleas (Ct. felis) on Dogs
Epe C., Coati N. & Stanneck D.
121
European Multicenter Field Trial on the Efficacy and Safety of a Topical Formulation of Imidacloprid
and Permethrin (Advantix™ ) in Dogs naturally infested with Ticks and/or Fleas
Hellmann K., Knoppe T., Krieger K. & Stanneck D.
124
Progress of the International Work of the “Imidacloprid Flea Susceptibility Monitoring Team”
Schroeder I., Blagburn B.L., Bledsoe D.L., Bond R., Denholm I., Dryden M.W., Jacobs D.E.,
Mehlhorn H., Mencke N., Payne P., Rust M.K. & Vaughn M.B.
126
Flea Allergy Dermatitis in Cats: Establishment of a Functional In vitro Test
Stuke K., Samson-Himmelstjerna G. von, Mencke N., Hansen O., Schnieder T. & Leibold W.
128
The Feline Leukemia Virus (FeLV) and the Cat Flea (Ctenocephalides felis)
Vobis M., D’Haese J., Mehlhorn H. & Mencke N.
131
Evaluation of the Efficacy of an Imidacloprid 10% / Moxidectin 2.5% Spot-on against
Sarcoptes scabiei var canis on Dogs
134

Page 7

C ONTE NT
S c ie ntific P rog ramme
Fourie L.J., Du Rand C. & Heine J.

Page 8

Parasitol Res (2003) 90: S105 – S106
E valuation of P e rme thrin and Imidac loprid for
P re ve ntion of B orre lia burg dorfe ri Trans mis s ion
from B lac kle g g e d Tic ks (Ixode s s c apularis ) to
B orre lia burg dorfe ri-fre e Dog s
DOI 10.1007/s00436-003-0904-8
L
vectored by ticks of the Ixodes ricinus complex1. I n
the USA, the nymphal and adult stages of the deer
tick, Ixodes scapularis, transmit the spirochete to
dogs and humans. Larval ticks are infected via
feeding on small rodents, most notably the white-
footed mouse. The bacteria are then transmitted
trans-stadially to nymphal and adult tick stages.
Lyme borreliosis is generally confined to locations
where the vector tick, the disease reservoir (the
white-footed mouse) and the preferred host for
adult I. scapularis ticks (the white tailed deer) are
abundant. In such areas, prevalence of infection in
dogs may range locally as high as 85%2.
yme borreliosis is a bacterial disease caused by
the spirochete Borrelia burgdorferi and
With high seroprevalence of canine Lyme borreliosis
in certain areas, and the significant public health
aspects of this disease, tick control on dogs exposed
to tick-infested habitats is now widely regarded as
paramount. There are two aspects of tick control that
are the most important. As Lyme borreliosis, and a
wide variety of other tick-borne diseases, are
transmitted via the tick bite, prevention of tick
attachment and feeding must be seen as the first
obligation of any tick control agent. Failing that (and
no compound may be expected to be 100% effective
in this at any given time) a tick control product must
be able to kill the tick before it has the opportunity to
transmit any pathogens.
While various tick control compounds have demon-
strated utility in the killing of ticks, little has been
written about the ability of these compounds to
prevent transmission of tick-borne disease to
susceptible dogs. Elfassy, et al1, demonstrated that
amitraz-impregnated collars could successfully
prevent transmission of B. burgdorferi from adult
Ixodes scapularis (deer) ticks to dogs 7 days after
treatment. Similar efficacy has been seen for fipronil
spray at days 7 and 33 post-treatment3. However,
to date, no reports have emerged for any of the
popular topical “spot-on” tick control products. As
these spot-on products occupy the overwhelming
majority of the tick control market, this lack of data
is a significant void in our understanding of the utility
of these products.
K9 Advantix is an effective tick control agent first
registered in November 2002 in the USA. It is a spot
on product containing 8.8% (w/w) imidacloprid and
44% (w/w) permethrin. It is labeled to repel and
kill four species of ticks, including Ixodes
scapularis, for up to four weeks. It is also labeled
to repel and kill mosquitoes and kill flea adults and
larvae. Methfessel and Turburg have demonstrated
in vitro that permethrin and imidacloprid enhance
one another’s activity against the parasites’
nervous system via separate and complementary
activity along the axon and post-synaptic
membrane, respectively4. Thus, this new
combination of two proven compounds provides a
S105
F ig ure 1 Two ticks attached with hair loss and redness
S P E NC E R J .A.1, B UTLE R J .M .1, S TAFFOR D K .C .2, P OUG H M .B .3, LE VY S .A.4,
B LE DS OE D.L.5& B LAG B UR N B .L.1
1Department of Pathobiology, College of Veterinary Medicine, Auburn University, Alabama, USA;
2Department of Forestry and Horticulture, Connecticut Agricultural Experiment Station, New Haven, Connecticut, USA;
3Animal Health Diagnostic Laboratory, Cornell University, Ithaca, New York, USA; 4Durham Veterinary Hospital, Durham,
Connecticut, USA; 5Bayer HealthCare LLC, Animal Health Division, Shawnee Mission, Kansas, USA

Page 9

useful tool for tick control.
While various reports have focused upon the clinical
and laboratory efficacy of K9 Advantix5,6, this
investigation was designed to assess the ability of
the product to prevent tick attachment and feeding
of ticks known to
B. burgdorferi as measured by seroconversion in
treated and untreated dogs.
be infected with
Adult beagle dogs confirmed to be free from B.
burgdorferi exposure via IFA testing, were
randomly assigned to two groups (treated and non-
treated control) of 8 animals each and housed
separately in a BL-2 facility. Field caught adult
Ixodes scapularis were used as source of B.
burgdorferi organisms. On day 0, Group 1 received
a single application of a spot on product containing
imidacloprid and permethrin (K9 Advantix™ )
according to the label dose. Group 2 served as
untreated controls and received no treatment. On
day 7, all dogs were infested with 100 I. scapularis
adults with an average B. burgdorferi infectivity
rate of 57.6%. On day 14 all ticks were removed
from the dogs and all dogs in both groups received
a dose of K9 Advantix to ensure any remaining ticks
were dead. (This was to limit potential exposure of
personnel to B. burgdorferi over the remainder of
the study). At this time, four tick attachment sites
from each of two dogs in the control (un-treated)
group were identified and marked. Biopsies were
obtained from these sites at day 91 and submitted
for PCR analysis.
Approximately 10 mls of whole blood were drawn
for ELISA testing for B. burgdorferi antibodies on
Days 14, 25, 42, 56, 70, and 91. Whole blood was
allowed to clot then centrifuged and the serum
separated for testing. Kinetics ELISA testing of all
samples was performed at the Animal Health
Diagnostic
Additionally, IFA testing was performed at Auburn
University on the samples collected on days 14, 25,
and 42 to provide an early screen confirming that
the untreated control dogs were successfully
infected.
Laboratory, Cornell University.
By day 42, all untreated control dogs had
seroconverted via IFA testing and all K9 Advantix-
treated dogs remained negative. One control dog
remained of equivocal infection status and another
remained negative via ELISA through day 56 but both
strongly converted by day 70. There was complete
agreement between IFA and ELISA on the status of
all treated dogs and all remained B. burgdorferi
negative at all sample points. The mean ELISA titers
of treated and untreated dogs are shown in figure 3.
In addition, skin punch biopsies obtained from
untreated control dogs were positive for B.
burgdorferi DNA.
The results of this study indicate that K9 Advantix
is effective 7 days after treatment in the prevention
S106
F ig ure 2 Tick stages: In their natural habitat, on a dog and engorged females
500
high positive
400
mid positive
300
low positive
200
equivocal
100
negative
0
DAY 14254256
n Control
7091
lK9 Advantix
F ig ure 3 Arithmetic mean antibody titers via kinetics ELISA

Page 10

Parasitol Res (2003) 90: S107 – S110
R e pe lle nt E ffic ac y of a C ombination C ontaining
Imidac loprid and P e rme thrin ag ains t S and F lie s
(P hle botomus papatas i) on Dog s
DOI 10.1007/s00436-003-0905-7
I
countries. Furthermore, canine leishmaniases have
a worldwide distribution and can be found in Asia,
Africa and America. First reports on canine leish-
maniasis were recently published also from the US,
it remains unclear until now whether the disease
was imported from abroad, or has already
established within the country. Leishmaniases are
vector-borne diseases: the promastigote stage of
the parasite is transmitted to the host during the
blood feeding of an insect vector, the sand fly. The
causative agents of canine leishmaniasis are
Leishmania infantum in the Mediterranean Basin and
the Middle East and L. chagasi in South and Central
America. Initially, L. chagasi was considered to be
distinct from L. infantum, however, recent
molecular studies indicate that they are
indistinguishable. Today we believe that the
parasite reached the New World in dogs transported
from Europe to the Americans by the colonists. L .
infantum/chagasi is also an important human health
problem and dogs serve as the main reservoir
animal. Several studies showed that the prevalence
of human leishmaniasis could be significantly
decreased with control of leishmaniasis in dogs.
nfections in dogs with the protozoan parasite
Leishmania are widespread in Mediterranean
M E NC K E N.1, VOLF P.2, VOLFOVA V.2& S TANNE C K D.1
1Bayer AG, BHC-Business Group Animal Health, D-51368 Leverkusen, Germany
2Charles University, Department of Parasitology, Prague, Czech Republic
F ig . 1 Life cycle of Leishmania
A Development in Man: 1 Flagellated L. donovaniparasites carried by
Phlebotomus species (promastigote stage) enter macrophages
(Giemsa stain); 2–6Intracellular development in macrophages and later
in endothelial cells; 7 Macrophages in perpheral blood containing
amstigote stages
B Development in the sand fly vector: 8Amastigote stages, within host
cells, in the fly’s midgut; 9 Growth and multiplication of the promasti-
gote stage; 10 Flagellate stage (metacyclic promastigote form) from
fly’s proboscis
C Development as in man A in animal reservoir (dogs, small rodents etc.)
Transmission by the sand fly can occur as follows:
From Man to ManA‘ B‘ A
From Animal to Animal C‘ B‘ C
From Animal to ManC‘ B‘ A
and vice versaA‘ B‘ C
Taken from: PIEKARSKI G. (1989) Medical Parasitology; Springer – Berlin,
Heidelberg, New York
S107
10
1
2
3
4
5
6
7
ab
a
b
8
A
B
C
9
10
1
2
3
4
5
6
7
8
9

Page 11

S108
Prevention of dogs from sand fly bites and thus
reducing the risk of infection with L. infantum i s
therefore our veterinary obligation.
B iolog y of Leishmania and their
vec tors
While there is no morphological differentiation
between the Leishmania
techniques implemented today distinguish the
previously described species as the L. donovani
complex (three species: L. donovani, L. infantum and
L. chagasi), the L. mexicana complex (three main
species: L.
L. amazonensis and L. venezuelensis), further L .
tropica, L.
L. aethiopica and the subgenus Viannia with four main
species (L. braziliensis, L. guyanensis, L. panamensis
and L. peruviana) .
species, molecular
mexicana,
major,
Within humans and dogs Leishmania multiply within a
parasitophorous vacuole of macrophages as
amastigotes (forms without flagella). Finally, these
macrophages rupture and amastigotes enter other
phagocytic cells, mainly of the reticulo-endothelial
systems in liver, spleen, bone marrow and lymph
nodes. Sand flies feeding on infected host ingest a
blood meal with infected monocytic cells. In the
midgut of the sand fly the amastigotes transform into
a flagellated promastigotes, multiply and then, during
the second blood feeding, they are transmitted to the
next vertebrate host. Development to the infectious
promastigote occurs under favorable tropical
conditions within 5 – 8 days. The incubation period in
dogs is several weeks to months.
>>
F ig . 2 Sand fly female (size 2.5 mm)

Page 12

Sand flies belong to the insect order Diptera,
suborder Nematocera. The Old World sand flies belong
to genus Phlebotomus, the New World ones to the
genus Lutzomyia. Both these genera are important
vectors of Leishmania parasites. The biology of the
adult sand fly is that of a typical bloodsucking
Nematocera: both sexes feed on sugar solutions but
females need a blood meal to produce eggs. Larvae
hatching from the eggs develop through 4 larval
instars. They are terrestrial and live in soil rich in
organic substrates where they also pupate. The adult
females seek hosts for a blood meal in a clear
circadian activity. They are nocturnal blood feeders,
resting over the hot day away from sunlight in
relatively cool and humid places, like cellars,
stables, crevices or rodent holes. Once landed on the
potential host, the dog or other mammal, they hop
over the coat aiming for less hairy place; in the head
region they like to bite around the muzzle, eye or
mouth. Similarly to other bloodsucking insects, the
sand fly saliva contains anticoagulants, vasodilatory
peptides and enzymes with antiinflammatory,
antihemostatic and anaesthetic properties. These
components of saliva are important for transmission
and serve as enhancing factors of the parasite
infection. Sand flies are fast feeders; once they
created
pool of blood in epidermis of the host they rapidly fill
their midgut with blood. Leishmania is well adapted
to this feeding habit, entering the host via the
proboscis with the saliva injected into the host.
C linic al C anine leishmaniasis
a small
Clinical features of canine leishmaniasis vary
widely, while skin lesions are the most usual
manifestation. The incubation period is 4 weeks to
several years. The pathomechanism of the infection
is a combination of chronic inflammation of skin,
liver, GI-tract, kidneys, eyes and bones and a immune
mediated polyarthritis, glomerulonephritis, arthritis
and uveitis. In addition, dogs presented to the clinic
often have concomitant infections, due to
immunosuppression thus complicating the diagnosis.
The skin lesions are alopecia with intense, dry
desquamation, usually on the head. In most cases
weight loss is common. Circulating immunocomplexes
causing glomerulonephritis, proteinuria and sub-
sequently renal failure is a common cause of death in
affected animals. Besides the dogs with visible
clinical signs of the disease, asymptomatic carriers
are frequently reported. While in endemic areas most
dogs have contact with the parasite, the prevalence
of the disease is usually up to 20%. The reason why
some dogs develop the disease and others are
resistant is not fully understood yet. Diagnosis of
canine leishmaniasis is complicated as most tests
available are not sensitive or specific enough.
Several treatment regimes are recommended but a
once dog got ill the parasites will never been
completely eliminated. Prevention of sand fly bites
is therefore the most important way to stop the
circulation of canine leishmaniasis.
Human Leishmaniasis
In humans the protozoan parasite of the genus
Leishmania causes cutaneous (CL), mucocutaneous
(MCL) and visceral (VL) leishmaniases. The WHO
reported that worldwide 350 million humans in 88
countries are at risk and 12 million people are
affected by leishmaniases, with about 1.5 – 2.0
Million new cases of CL and 0.5 Million new cases of
VL cases annually. More than 90% of the VL cases are
reported from Bangladesh, Brazil, India, Nepal and
Sudan. Visceral leishmaniasis, also known as ‘Kala-
azar’ is caused by L. infantum in the Old World, L .
chagasi in the New World, and by L. donovani in Africa
and Asia. Coinfection in humans with immuno-
deficiency syndroms like AIDS is common. After
incubation period (usually 2-8 months) patients
S109
R e pe lle nt E ffic ac y of Imidac loprid and P e rme thrin ag ains t S and F lie s
F ig . 3 Dogs with skin lesions

Page 13

develop pyrexia, wasting and hepatosplenomegaly;
especially children are at risk. There is a long list of
clinical findings, with fever, discomfort from an
enlarged spleen, abdominal swelling, weight loss,
cough and diarrhea being the most prominent once.
While untreated the mortality is about 90%. After
successful recovery from VL due to L. donovani
infection, patients may develop so-called ‘post kala
azar dermal leishmaniasis’.
The mucocutaneous form (Espundia) occurs in some
cases
L. braziliensis infection in South America. Disease is
fully manifested months or years after the cutaneous
sores have healed. Papules and ulcerative lesions
occur on the nose, mouth and larynx and finally may
destroy the whole face.
of
In the Old World, L. major and L. tropica are the
causative pathogens of the cutaneous form (oriental
sore), while in the New World this form is caused
mostly by the parasites of L. mexicana and L .
brasiliensis complexes. Primary skin lesions occur
at the site of sand fly bite, often at unprotected body
regions like arms, legs and in the face. Most common
type of lesion is a chronic ulcer with an indurated
margin. The majority of these lesions are self-healing
in several months leaving a scar.
S110
F ig . 4 Phlebotomus papatasi male (left) and female
Taken from Mühlens P., Nauck E. & Vogel H. (1942), Krankheiten und Hygiene
der warmen Länder. Georg Thieme, Leipzig

Page 14

Parasitol Res (2003) 90: S111 – S112
E valuation of the E ffic ac y of an Imidac loprid 10 % /
M oxide c tin 1% S pot-on ag ains t Otode c te s c ynotis
in C ats
DOI 10.1007/s00436-003-0906-6
OB J E C TIVE
The aim of this study was to determine whether a
single or two treatments, four weeks apart, with a
novel, topically applied, formulation of Imidacloprid
10% plus Moxidectin 1%, applied at a dose of 0.1
ml/kg body mass, would be effective in the
treatment of ear mite, Otodectes cynotis,
infestations in cats.
S TUDY DE S IG N AND M E THODS
This study was performed in compliance with VICH
GL9 “Good Clinical Practice, June 2000” at ClinVet
International (Pty) Ltd, Bloemfontein, Republic of
South Africa. Thirty cats naturally infested with O.
cynotis were allocated to three groups of 10 cats
each by randomisation through minimization with
Day –1 body weight as the primary criterion. Group
1 served as a negative placebo treated (Days 0 and
+28) control. Group 2 received a single treatment
with the Imidacloprid/Moxidectin solution on Day 0
and a placebo treatment on Day +28. Group 3 was
treated with the Imidacloprid/Moxidectin solution
on Days 0 and +28. Treatments were blinded. The
cats were kept individually in stainless steel cages
in environmentally controlled rooms. The three
different treatment groups were kept under similar
conditions in adjacent rooms. Eight days after the
first treatment and thereafter at fortnightly
intervals, the ears of the cats were examined for
the presence of ear mites by using an otoscope, ear
scrapes and dry cotton swabs. Assessments on Day
+50 were performed on anaesthetized cats. The
study schedule is summarized in Table 1.
Efficacy evaluation was based on the presence of
mites in the ears of cats. The success rate in each
S111
FOUR IE L.J .1, K OK D.J .2& HE INE J .3
1University of the Free State, Bloemfontein, Republic of South Africa;
2ClinVet International (Pty) Ltd., Bloemfontein, Republic of South Africa;
3Bayer AG, BHC-Business Group Animal Health, D-51368 Leverkusen, Germany
F ig ure 1 Debri in the ear of a cat infested with Otodectes cynotis mites (left) and the healthy ear of a cat (right) after two treatments with
Imidacloprid 10% / Moxidectin 1%, applied 28 days apart at a dose of 0.1 ml/kg body mass
AcclimatizationAllocation to groups TreatmentPre- and Post-treatment mite assessments
Day: –7Day: –1 Day: 0; +28Day: –3; +8; +22; +36; +50
Ta ble 1 Synoptic overview of the study layout

Page 15

treatment group for Days +22 and +50 was
calculated as follows:
Success rate (%)=x
100, where
___ ·___
y
1
x = number of cats observed with no live mites
y = total number of cats in group
R E S ULTS
Live mites, varying in numbers from 1 to 66 were
counted in scrapings taken (Day –3) from the ears
of all 30 cats included in the study. Live mites were
observed in the ears of all the cats in the placebo
treated group on all the assessment days. In the case
of the group of cats which received a single
treatment either one or two cats still harboured live
mites in their ears on the different assessment
days. No mites were observed in the ears of cats,
which received two treatments, on any of the
assessment days. The treatment success (%) for
Groups 2 and 3 are summarized in Table 2.
C ONC LUS ION
A
Imidacloprid/Moxidectin solution applied at a
dosage of 0.1 ml/kg body mass resulted in a treat-
ment success rate of 80% as assessed 50 days
after treatment. Two treatments with the
Imidacloprid/Moxidectin solution, four weeks
apart, at a dosage of 0.1 ml/kg body mass, was
efficacious in curing all cats from Otodectes cynotis
infestations as assessed 22 days after the second
treatment (Day +50).
single treatment with the
l
S112
Ta ble 2 Summary of the treatment success rate (%)
for Groups 2 and 3 as assessed on Days +22 and +50,
respectively.
DayGroup 2: Treated
once (Day 0)
90
80
Group 3: Treated twice
(Day 0 and +28)
100
100
+22
+50
F ig ure 2 Female mite with a visible egg