Wiener Tierärztliche Monatsschrift – Veterinary Medicine Austria
100 (2013)
Aus der Tierärztlichen Klinik Birkenfeld1, Deutschland, und dem Labor Focus Veterinary Histopathology
International2 , United Kingdom
Cowpox virus infection in a cat in Southwest Germany –
a case presentation
C. OUSCHAN1*, J. REST2 and S. PETERS1
received April 1, 2013
accepted May 28, 2013
Keywords: cowpox virus infection, cat, case report.
Summary
In Europe, the cowpox virus (CPXV) is one of the
causes of skin diseases in domestic animals and
humans with localized or disseminated appearance.
Wood mice and particularly bank voles form the
reservoir of the virus. Cats may be infected via
contact with these rodents and are regarded as the
main source of infection for humans. This case
report describes a generalized CPXV skin infection
in a cat with concurrent ulcerative stomatitis and a
positive rapid test for feline leukaemia virus antigen.
Histopathological examination of skin biopsies
showed multifocal ulcerative to necrotizing
dermatitis with typical epithelial eosinophilic
intracytoplasmic inclusion bodies. Because of its
zoonotic potential, cowpox virus infection should
always be considered in the differential diagnosis of
feline ulcerative dermatitis.
Introduction
According to genotypic data, cowpox virus
(CPXV) is a composite of several (up to five) species
that can infect various animals and humans
(CARROLL et al., 2011). It belongs to the genus
Orthopoxvirus, family Poxviridae. Wild rodents,
especially bank voles (Myodes glareolus) and
wood mice (Apodemus sylvaticus), seem to be
the primary reservoir (CHANTREY et al., 1999; HAZEL
et al., 2000). A study in the UK estimates that one in
six wild mice hosts the virus (HAZEL et al., 2000).
Cats are infected while hunting. Late summer and
autumn are the main season for poxvirus infections in
animals and humans, presumably due to the
population peak of mice and voles at this time
(KAYSSER et al., 2010).
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Schlüsselwörter: Kuhpockeninfektion, Katze, Fallbericht.
Zusammenfassung
Kuhpockeninfektion bei einer Katze in Südwestdeutschland – eine Fallpräsentation
Zusammenfassung
Einer der Gründe für Hauterkrankungen bei Haustieren und Menschen, die sowohl lokalisiert wie disseminiert auftreten, ist das Kuhpockenvirus. Wald- und insbesondere Wühlmäuse sind für dieses Virus das
Primärreservoir. Katzen können durch den Kontakt mit
ihnen infiziert werden und stellen die wichtigste Quelle
für die Infektion beim Menschen dar. Der vorliegende
Bericht beschreibt einen Fall von generalisierten Hautveränderungen und Ulzerationen der Mundschleimhaut bei einer Hauskatze mit positivem Felinem
Leukämievirus-Antigen. Die histopathologische Untersuchung der Veränderungen ergab eine multifokale,
nekrotisierende Dermatitis mit für Poxvirusinfektionen
typischen eosinophilen intrazyoplasmatischen Einschlusskörperchen. Aufgrund des zoonotischen Potenzials muss die Orthopoxvirus-Infektion in Fällen ulzerativer Dermatitiden bei Katzen differentialdiagnostisch besonders beachtet werden.
Historically, cattle in contact with people were considered to be the species predominantly infected and
thus the source for viral transmission to humans.
Cowpox virus infections have a broad zoonotic potential (WOLFS et al., 2002; HERDER et al., 2011). Not
only cattle but also pet rats (CAMPE et al., 2009;
WOLFS et al., 2002), cats (THOMSETT et al., 1978;
CHANTREY et al., 1999), dogs (VON BOMHARD et al.,
2010) and humans (CZERNY et al., 1991; WOLFS et al.,
2002; CAMPE et al., 2009; CARLETTI et al., 2009)
may be affected. An infection in cats was first described
by THOMSETT et al. (1978). Since then additional
cases have been described in the UK (WEBSTER and
JEFFERIES, 1984) and in other countries, including
Germany (BALLAUF et al., 1989; MAHNEL, 1991;
Wiener Tierärztliche Monatsschrift – Veterinary Medicine Austria
100 (2013)
VON BOMHARD et al., 1992; KAYSSER et al., 2010;
HERDER et al., 2011) and Austria (NOWOTNY et al.,
1994). Recent studies describe cats as the
primary source of human infection (CARLETTI et al.,
2009); CPXV infection in dogs is very rare (VON
BOMHARD et al., 2010).
CPXV infection in cats usually leads only to
cutaneous lesions. The disease is characterized by a
primary solitary lesion occurring about six days post
infection, followed by viraemia and widespread skin
lesions approximately a week after the primary lesion.
The lesions are usually not pruritic and the primary
changes are mainly found on the anterior half of the
body. According to the literature, males are more
often affected, possibly because of their lifestyle.
Secondary bacterial or fungal infections may
worsen the skin lesions and cause progression
(VON BOMHARD et al., 1992).
With its zoonotic potential, cowpox virus infection
should always be considered in the etiological
differential in feline necrotizing dermatitis.
Case Report
The patient was ‘Mikesch’, a 10.5 year-old male
castrated cat living mainly outdoors and vaccinated
(Purevax® RCP, rabies). He received regular flea and
tick prevention (Fipronil; Frontline® Spot On) and had
been dewormed in late July 2011 (Milbemycin-Oxim,
Praziquantel; Milbemax®). No other pets lived in the
same household.
History
In October 2011, Mikesch disappeared for four days
and returned with purulent crusts on the skin of one
front paw. The first veterinarian consulted suspected
a road traffic accident and started treatment
with Meloxicam (Metacam®, 0.1 mg/kg SID s.c.),
Marbofloxacin (Marbocyl®, 2 mg/kg SID p.o) and
an Elizabethan neck collar. When the skin lesions
worsened, Mikesch was given a cortisone depot
injection (details not recorded).
When the patient was presented at our referral
clinic, the condition had deteriorated with spreading
skin lesions affecting all four feet. By then, skin
problems had been present for four weeks and the
animal had not received any therapy for about a week.
The owners had no skin lesions.
On general clinical examination the cat was
depressed, slightly pale and dehydrated. A complete
dermatological examination was performed. Both front
paws presented swollen, ulcerative lesions of 0.5 to
1.5 cm in diameter that bled on pressure. The nose
showed an alopecic crusty spot of about 0.5 cm in
diameter. Multiple smaller lesions were distributed over
the body. Cytological examination of impression
smears showed intracellular coccal bacteria, degenerated neutrophils and some acantholytic epithelial cells.
Fig. 1: Alopecic crusty spot, about 0.5 cm in diameter, on the nose
of a cat with cowpox infection
With the exception of a slightly elevated level of
creatinine, haematological and biochemical examinations showed no abnormalities. The creatinine level
was within the reference range on subsequent
testing. The rapid screening test for feline leukaemia
virus (FeLV) antigen was positive, while the rapid
screening test for feline immunodeficiency virus (FIV)
antibodies was negative (SNAP Combo plus®). The
ANA (anti-nuclear antibody) test was negative.
Protein electrophoresis showed an elevated alphaglobulin, consistent with an acute inflammatory
disease.
The owners were informed about the risk of
anaesthesia due to the FeLV status. The cat was
anaesthetized with butorphanol (Dolorex®) as premedication and propofol (Propofol®) for maintenance.
Seven skin biopsies were taken to distinguish the
potential clinical diagnoses (bacterial and fungal
Fig. 2: Cat with cowpox infection showing multiple lesions all over
the body, especially on the paws
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Wiener Tierärztliche Monatsschrift – Veterinary Medicine Austria
100 (2013)
infections, eosinophilic granuloma, virus infection, autoimmune disease and neoplasia; MILLER et al., 2013).
The biopsies were sent to Focus Veterinary Histopathology International (Great Britain).
Histopathology
The thick crust was colonized by bacteria but did not
contain any acantholytic cells. The epidermis had sharply demarcated necroses and ulcerations. Intracytoplasmic angular accumulations of eosinophilic material
varying in size from 7-14 μm were present focally in surviving surface and follicular epithelium. The dermis had
a perifollicular infiltrate including macrophages, neutrophils and lymphocytes with necrosis of hair follicles. No
mites, yeasts or fungi were seen.
The morphological diagnosis was deep necrotizing folliculitis and dermatitis. The eosinophilic accumulations in
the epithelium were consistent with viral inclusion bodies
indicating an orthopox infection (cowpox or catpox). The
finding of characteristic inclusion bodies with compatible
histopathology is an accepted method for confirming the
diagnosis of pox infection (GROSS et al., 2005). No further
examination (PCR) was undertaken because of characteristic finding of inclusion bodies. The finding of characteristic inclusion bodies with compatible histopathology
is an accepted method for confirming the diagnosis of
pox infection (GROSS et al., 2005).
Therapy
There is no specific therapy for poxvirus infection.
Broad-spectrum antibiotics to prevent secondary bacterial infections are recommended, while glucocorticoids are contraindicated (MILLER et al., 2013). In this
case the cat was given amoxicillin-clavulanic acid 25
mg/kg BID (Amoxclav Hexal Injektionslösung 500/100
mg) and enrofloxacin (Baytril®, 5 mg/kg p.o. SID). He
was also given analgesics: buprenorphine (Temgesic®,
0.1 mg/kg TID) and meloxicam (Metacam®; 0.1 mg/kg
s.c. SID). The crusty lesions were carefully bathed with
chlorhexidine (4%) in a diluted solution (1:6). Precautions
were taken against transmission to humans.
The skin lesions improved during treatment. The feet
became less swollen and the inflammation reduced.
The general demeanour of the cat improved, but after a
week, the cat again became lethargic, refused to eat
and clinical examination showed new skin lesions and
ulceration and inflammation of the oral cavity. With
progression of clinical disease and poor prognosis, the
cat was euthanized. The owners refused further pathological examination.
Sources of Supply
Purevax® RCP, Tollwut, Merial, Germany; Fipronil
(Frontline® Spot On, Merial, Germany); Milbemycin-Oxim
und Praziquantel (Milbemax®, Novartis, Germany);
Meloxicam (Metacam®, Böhringer Ingelheim-Vetmedica
GmbH,
Ingelheim,
Germany);
Marbofloxacin
(Marbocyl®, Vetoquinol GmbH, Germany); butorphanol
328
Fig. 3: Histopathology of a skin biopsy of a cat with cowpox infection: The epidermis is poorly stained because there is significant
necrosis. Central nuclei show karryorhexis. Red intracytoplasmic
pox inclusion bodies can be seen in the cytoplasm of residual epithelial cells (arrows) (arrows; H&E, x400).
(Dolorex®, Intervet, Germany); propofol (Propofol®,
Norbrook Laboratories Ldt, UK; Alfavet Tierarzneimittel
GmbH, Neumünster, Germany); amoxicillin clavulanicacid (Amoxclav Hexal Injektionslösung 500/100 mg,
Hexal AG, Germany); enrofloxacin (Baytril®, Bayer, Germany); buprenorphine (Temgesic®, Bayer Vital, Kiel),
Deutschland; rapid screening test for Feline Immunodeficiency Virus (SNAP Combo plus®, Idexx laboratories, IDEXX Europe B.V.; P.O. Box 1334; NL-2130; EK
Hoofddorp).
Discussion
The present case describes a generalized cowpox
virus infection in a cat, which was diagnosed in
autumn. Most feline CPXV infections occur in late
summer to autumn, when rodent reproduction usually
peaks. An extremely mild winter in 2007 caused an
increased population of voles and the highest number
of CPXV infections in cats in Germany in late summer
2008 (KAYSSER et al., 2010).
The disease is a zoonosis and infected cats represent
a potentially serious threat to their owners (LUBACH,
1992). The infection is transmitted by close contact with
infected animals. CPXV has been shown to have been
transmitted from pet rats to humans (BECKER et al.,
2009; CAMPE et al., 2009) and from cats to humans
(MAHNEL, 1991; VON BOMHARD et al., 1992).
As vaccinia virus vaccination was discontinued in
the 1980s, cowpox virus infections are steadily
increasing in Europe (BLACKFORD et al., 1993;
HERDER et al., 2011). The disease is usually mild in
humans but children and immune-suppressed
people are severely compromised. In the present
case, the owners were an elderly couple with close
contact with their cat. Neither of them developed any
clinical signs of poxvirus infection, possibly because
of immune protection from their vaccinia vaccination.
Wiener Tierärztliche Monatsschrift – Veterinary Medicine Austria
The prognosis for cowpox is generally good.
Secondary bacterial or fungal infections may worsen
the skin lesions and cause their progression. Approximately 20% of infected cats develop oral vesiculation
or ulceration (MILLER et al., 2013). The cat in this case
also developed ulcerative glossitis, due to the CPXV
or to another infection. Generalized CPXV infections
are usually associated with underlying immunosuppressive conditions, such as infection with FeLV, parvovirus (SCHAUDIEN et al., 2007) or FIV. Therapy with
corticosteroids is therefore generally contraindicated.
As shown in the present case, concurrent FeLV infection and corticosteroid therapy may lead to a severe
generalized systemic infection. There is only one reported case of recovery from pneumonia in which
both poxvirus and feline herpes virus were found
(JOHNSON et al., 2009). Fatal necrotizing pox viral
100 (2013)
pneumonia without skin lesions was recorded in 2007
(SCHÖNIGER et al., 2007).
The infection may be misdiagnosed. Lesions induced by poxvirus bear a macroscopic resemblance
to herpes virus 1-associated facial and nasal dermatitis and stomatitis (HARGIS and GINN, 1999) but are
histologically distinct. Other clinical differential diagnoses are eosinophilic granuloma, pyoderma, other
viral infections, autoimmune diseases such as
pemphigus foliaceus or neoplasia, all of which can be
distinguished by histopathology.
Diagnosis of CPXV infection is based on clinical appearance and histopathology – typical inclusion bodies
in epithelial cells indicate the diagnosis – or PCR of skin
lesions. As such infections are becoming more frequent, we hope this case report will raise public awareness and reduce the individual risk of human infection.
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*Corresponding author`s address:
Claudia Ouschan,
S.v.Hueber-Weg 3, 9121 Tainach
E-mail: [email protected]