In vitro binding of cefovecin to plasma proteins in Australian marsupials and plasma concentrations of cefovecin following single subcutaneous administration to koalas (Phascolarctos cinereus).

BACKGROUND: Cefovecin has a long duration of antibiotic activity in cats and dogs, somewhat attributable to its high plasma protein binding. AIMS: To determine the cefovecin binding to plasma proteins in vitro in selected Australian marsupials and to quantify the change in cetovecin concentration over time following subcutaneous injection in koalas. METHODS AND RESULTS: Various cefovecin concentrations were incubated with plasma and quantified using HPLC. The median (range) bound percentages when 10 µg/mL of cefovecin was incubated with plasma were 11.1 (4.1-20.4) in the plasma of the Tasmanian devil, 12.7 (5.8-17.3) in the koala, 18.9 (14.6-38.0) in the eastern grey kangaroo, 16.9 (15.7-30.2) in the common brush-tailed possum, 37.6 (25.3-42.3) in the eastern ring-tailed possum and 36.4 (35.0-38.3) in the red kangaroo, suggesting that cefovecin may have a shorter duration of action in these species than in cats and dogs. Cefovecin binding to plasma proteins in thawed, frozen equine plasma was also undertaken for assay quality control and the median (range) plasma protein binding (at 10 µg/mL) was 95.6% (94.9-96.6%). Cefovecin was also administered to six koalas at 8 mg/kg subcutaneously and serial blood samples were collected at 3, 6, 24, 48, 72, 96 h thereafter. Cefovecin plasma concentrations were not quantifiable in four koalas and in the other two, the mean plasma concentration at t = 3 h was 1.04 ± 0.01 µg/mL. CONCLUSION: Because of the limited pharmacokinetic data generated, no further pharmacokinetic analysis was performed; however, a single injected bolus of cefovecin is likely to have a short duration of action in koalas (hours, rather than days).

Pharmacokinetics of posaconazole in koalas (Phascolarctos cinereus) after intravenous and oral administration.

The pharmacokinetic profile of posaconazole in clinically normal koalas (n = 8) was investigated. Single doses of posaconazole were administered intravenously (i.v.; 3 mg/kg; n = 2) or orally (p.o.; 6 mg/kg; n = 6) with serial plasma samples collected over 24 and 36 hr, respectively. Plasma concentrations of posaconazole were quantified by validated high-performance liquid chromatography. A noncompartmental pharmacokinetic analysis of data was performed. Following i.v. administration, estimates of the median (range) of plasma clearance (CL) and steady-state volume of distribution (Vss ) were 0.15 (0.13-0.18) L hr-1  kg-1 and 1.23 (0.93-1.53) L/kg, respectively. The median (range) elimination half-life (t1/2 ) after i.v. and p.o. administration was 7.90 (7.62-8.18) and 12.79 (11.22-16.24) hr, respectively. Oral bioavailability varied from 0.43 to 0.99 (median: 0.66). Following oral administration, maximum plasma concentration (Cmax ; median: 0.72, range: 0.55-0.93 µg/ml) was achieved in 8 (range 6-12) hr. The in vitro plasma protein binding of posaconazole incubated at 37°C was 99.25 ± 0.29%. Consideration of posaconazole pharmacokinetic/pharmacodynamic (PK/PD) targets for some yeasts such as disseminated candidiasis suggests that posaconazole could be an efficacious treatment for cryptococcosis in koalas.

Storage mite contamination of commercial dry dog food in south-eastern Australia.

OBJECTIVE: To evaluate contamination of unopened and opened stored sources of commercial dry dog food by viable storage mites. DESIGN: Prospective laboratory and field study. MATERIAL AND METHODS: Samples were collected from nine brands of previously unopened bags (new bags) of dry food and 20 field sources of stored dry food in homes in Sydney and Canberra, Australia. All samples were initially examined for the presence of mites using a stereo-binocular microscope and then placed in separate filter-paper-sealed containers. Field samples were incubated at an average temperature of 29°C and 78% relative humidity (RH) for 5 weeks and then at average 26°C/83% RH for 8 weeks. Paired new-bag samples were stored under room conditions (average 23°C/47% RH) and controlled incubator conditions (average 26°C/80% RH) for 6 weeks. All samples were thoroughly examined for mites, mite eggs and visible mould once weekly using a stereo-binocular microscope. RESULTS: Storage mites were not visualised in any of the field samples or in new-bag samples stored at room temperature. Storage mites, identified as Tyrophagus putrescentiae, were visualised in increasing numbers in seven of nine new-bag samples after incubation, with first mites and then eggs evident after 3 weeks of incubation. CONCLUSIONS: We confirmed the presence of viable storage mites in a range of previously unopened commercial dry dog foods in Australia and confirmed the possibility of heavy storage mite contamination for dry food stored under conditions of moderate temperature and high humidity. These findings have relevance to storage mite and/or dust mite sensitivity in canine atopic dermatitis.

Canine superficial bacterial pyoderma: evaluation of skin surface sampling methods and antimicrobial susceptibility of causal Staphylococcus isolates.

OBJECTIVE: To evaluate three easily performed methods of skin surface sampling for bacterial culture of Staphylococcus isolates obtained from dogs with superficial bacterial pyoderma (SBP) presenting to two veterinary teaching hospitals in Sydney, Australia, and to determine the antimicrobial susceptibility of isolates. DESIGN: Prospective study of 27 dogs with SBP. Cytologically confirmed SBP lesions were sampled for bacterial culture using a dry cotton swab, a saline-moistened cotton swab and a skin surface scraping. Isolates were identified by standard discriminatory phenotypic and biochemical analyses, and confirmed using matrix-assisted laser desorption ionisation time of flight mass spectrometry (MALDI-TOF MS). Susceptibilities to 14 antimicrobials were determined by disk diffusion and by detection of the mecA gene using PCR. Sampling methods were compared according to bacterial yield, antibiograms and bacterial phenotypic analysis. Location of causative bacteria was evaluated via 8-mm punch skin biopsies using haematoxylin and eosin, Gram-Twort and Giemsa staining, and fluorescence in situ hybridisation (FISH). RESULTS: Staphylococcus sp. were isolated from lesions in all dogs, either S. pseudintermedius (24 dogs) or S. schleiferi (3 dogs). Susceptibility was highest to cephalexin (96%) and amoxycillin clavulanate (96%). Methicillin resistance assessed by mecA real-time PCR and phenotypic oxacillin resistance was found in one dog (4.3%). Routine histology and FISH revealed bacteria within superficial stratum corneum. CONCLUSION: Staphylococcal isolates from canine SBP demonstrated high susceptibility to common empirical antimicrobials. Histological techniques confirmed presence of bacteria at superficial sites, likely to be accessed by the sampling techniques. The three techniques afforded similar results and may be equally suitable for obtaining samples for culture.

Transmission of Mycobacterium tuberculosis from an Asian elephant (Elephas maximus) to a chimpanzee (Pan troglodytes) and humans in an Australian zoo.

Mycobacterium tuberculosis is primarily a pathogen of humans. Infections have been reported in animal species and it is emerging as a significant disease of elephants in the care of humans. With the close association between humans and animals, transmission can occur. In November 2010, a clinically healthy Asian elephant in an Australian zoo was found to be shedding M. tuberculosis; in September 2011, a sick chimpanzee at the same zoo was diagnosed with tuberculosis caused by an indistinguishable strain of M. tuberculosis. Investigations included staff and animal screening. Four staff had tuberculin skin test conversions associated with spending at least 10 hours within the elephant enclosure; none had disease. Six chimpanzees had suspected infection. A pathway of transmission between the animals could not be confirmed. Tuberculosis in an elephant can be transmissible to people in close contact and to other animals more remotely. The mechanism for transmission from elephants requires further investigation.

Extensive epidermal naevus in a foal.

CASE REPORT: A 2-month-old Standardbred filly was presented for examination and treatment of extensive congenital skin lesions that had a linear distribution on the left front leg extending from the dorsal midline to the metacarpal region. The lesions were surgically excised under general anaesthesia. Surgical excision was curative and there were no signs of recurrence 6 weeks after surgery. The number and distribution of lesions were more extensive than in previously reported cases of congenital papillomas, which have also been described as epidermal growth abnormalities (naevi or hamartomas). Early reports of congenital papillomas suggest in-utero infection with papillomavirus may be responsible, despite a lack of histological features associated with papillomavirus infection. Papillomavirus immunohistochemistry has subsequently proven negative in tested cases. CONCLUSIONS: The presence at birth, their appearance and the extensive distribution of lesions in this case is similar to verrucous epidermal naevus of humans. A name change from congenital papilloma to epidermal naevus is proposed for this condition in horses.

Cutaneous adverse food reactions in cats: retrospective evaluation of 17 cases in a dermatology referral population (2001-2011).

OBJECTIVE: To better characterise cutaneous adverse food reactions (AFR) in cats, including the diagnostic challenges. DESIGN: Retrospective evaluation of cases presenting to a dermatology referral service. METHODS: Cats were identified by a computerised medical record search. AFR was confirmed by clear deterioration on normal food re-challenge after completing an elimination diet, followed by improvement returning to the test diet. Prevalence, and breed, sex or age predispositions were compared with the base referral population. Patient records were reviewed for historical features, clinical presentations, concurrent dermatoses and dietary details. RESULTS: A total of 17 cats were identified with cutaneous AFR, with no breed or sex predisposition determined. Age of onset ranged from 3 months to 9 years, with a mean of 3.5 years. Prevalence was 6% of dermatoses and 10% of cutaneous hypersensitivities in the referral cat population. Cats typically presented with severe, perennial, non-seasonally flaring pruritus affecting the face/head, neck and/or ventral abdomen. Concurrent hypersensitivities were confirmed in 6 cats and/or suspected in another 5 cats. Home-prepared elimination diets were completed by 16 cats; 8 cats had initial poor response to minimum 6-week commercial hydrolysed protein diets. Identified adverse foods included fish in 2 cats, and chicken, beef, commercial dry, and some canned foods, each in 1 cat. CONCLUSIONS: The prevalence of cutaneous AFR in the general cat population is likely to be greater than 6%. A range of clinical presentations occur and practical challenges to diagnosis include reliance on strict adherence to dietary exclusion/provocation trials and misleading responses related to concurrent dermatoses and owner perceptions.

Unique presentation of normolipaemic cutaneous xanthoma in a cat.

CASE REPORT: A normolipaemic 7-year-old female spayed Domestic Shorthair was initially presented with a history of pruritus for several years and diagnosed with concurrent atopic dermatitis, flea bite hypersensitivity and adverse food reaction. The hypersensitivities were controlled with cyclosporin, allergen-specific immunotherapy, topical flea control and a restricted diet. Five months after initial presentation, the cat developed a non-healing nodular ulcerated cutaneous lesion in the left axilla and also developed immune-mediated haemolytic anaemic (IMHA). The IMHA was stabilised, but the axillary lesion persisted and progressed to a diffuse, firm, yellowed subcutaneous swelling over the ventral body approximately 20 months later. Histopathology was consistent with cutaneous xanthoma. The cat was normolipaemic and being fed a home-prepared diet of lean kangaroo meat and pumpkin to manage pruritus associated with adverse food reactions. No underlying malignancy was detected on routine screening tests. CONCLUSION: A diffuse, planar form of cutaneous xanthoma occurring without associated lipaemia has not been previously reported in cats.

Poxvirus infection outbreak in common ringtails (Pseudocheirus peregrinus).

Viruses belonging to the Poxviridae family have long been recognised as pathogens of invertebrates and vertebrates alike. Poxvirus infection in Australian macropodids is well described, but few cases have been documented in marsupial species beyond this family. Only one instance has been previously reported in the common ringtail (Pseudocheirus peregrinus). This case report describes a poxvirus infection outbreak in a group of common ringtails held within a zoological collection in eastern Australia.

Uterine adenomyosis in an orang-utan (Pongo abelii/pygmaeus).

A 48-year-old, multiparous, female hybrid orang-utan (Pongo abelii/pygmaeus) was investigated after a 3-year history of irregular and excessively heavy menstrual bleeding. Opportunistic pelvic examinations over a 2.5-year period were non-diagnostic. Medical therapy was not effective. A subtotal hysterectomy with bilateral salpingo-ovariectomy was performed. A pedunculated mass spanning 90% of the uterine lumen was seen grossly, and histopathology confirmed uterine adenomyosis. Adenomyosis is defined as the ectopic occurrence or diffuse implantation of endometrial tissue, including glands and stroma, into the myometrium. It is common in older, usually premenopausal, multiparous women and is frequently associated with other uterine pathology, including endometrial hyperplasia and leiomyomas. The most common clinical signs are dysmenorrhoea and heavy menstrual bleeding; however, up to 35% of women are asymptomatic. Diagnosis is difficult and requires myometrial sampling and an experienced pathologist. A hysterectomy in this case was diagnostic and curative. There have been few reports of uterine adenomyosis in non-human primates and none reported in an orang-utan. Uterine adenomyosis should be considered in the differential diagnosis in any multiparous, aged, non-human female primate with irregular and excessively heavy menstrual bleeding, and hysterectomy with bilateral salpingo-ovariectomy is recommended as a diagnostic and therapeutic solution.

Multifocal papular deep bacterial pyoderma in a Boxer dog caused by Pseudomonas aeruginosa.

A young adult Boxer dog was presented with a papular dermatitis on the dorsal back and ventral neck that had developed while it was being treated with cyclosporine and cephalexin for atopic dermatitis and secondary superficial staphylococcal pyoderma, respectively. Histopathology demonstrated nodular to diffuse pyogranulomatous dermatitis with focal furunculosis. Numerous bacterial rods, free in the tissue and engulfed by neutrophils and macrophages, could be demonstrated on stained samples (haematoxylin-eosin; Giemsa). Bacterial culture from an aseptically collected skin biopsy punch sample yielded a pure growth of Pseudomonas aeruginosa, sensitive to a variety of antimicrobials. Successful treatment was accomplished following discontinuation of cyclosporine and an extended course of enrofloxacin. There has not been a recurrence of the pseudomonal pyoderma during the subsequent 2 years.

Do free-ranging common brushtail possums (Trichosurus vulpecula) play a role in the transmission of Toxoplasma gondii within a zoo environment?

To investigate the possible role of common brushtail possums (Trichosurus vulpecula) in the transmission of Toxoplasma gondii within a zoo environment, a serological survey of a free-ranging population resident within Taronga Zoo, Sydney, Australia was undertaken using the modified agglutination test (MAT). For comparison, the seroprevalence of T. gondii antibodies was also assessed in a possum population inhabiting a felid-free, non-urban woodland habitat. Six of 126 possums (4.8%) from the zoo population had antibodies to T. gondii with a MAT titre of 25 or higher, while in contrast, all of the 17 possums from woodland were seronegative. These observations suggest that possums were at a higher risk of exposure to the parasite as a consequence of co-existing with domestic, stray and captive felids associated with urbanisation. Screening of captive felids at the zoo indicated 16 of 23 individuals (67%) and all 6 species were seropositive for T. gondii, implicating them as a possible source of the parasite within the zoo setting. In addition captive, non-felid carnivores including the chimpanzee (Pan troglodytes), saltwater crocodile (Crocodylus porosus), dingo (Canis lupis) and leopard seal (Hydrurga leptonyx) were tested for the presence of T. gondii antibodies as these species predate and are a leading cause of death amongst zoo possums. In total, 5 of 23 individuals (22%) were seropositive, representing 2 of the 4 carnivorous species; the dingo and chimpanzee. These data suggest that carnivory was not a highly efficient pathway for the transmission of T. gondii and the free-ranging possum population posed minimal threat to the health of zoo animals.

Cryptococcus neoformans var. gattii in the koala (Phascolarctos cinereus): serological evidence for subclinical cryptococcosis.

Cryptococcus neoformans var. gattii has been shown to have a strong association with eucalypts frequently used by koalas and, not surprisingly, it has been shown to colonize the nasal cavities of koalas. The progression from nasal colonization to tissue invasion is critical to understanding the pathogenesis of cryptococcosis in this species and provides a model for pathogenesis of cryptococcosis in other species. Cryptococcal antigenaemia was detected in twenty-eight healthy koalas from three different regions. This was interpreted as representing limited subclinical disease. One koala developed cryptococcal pneumonia 6 months after leaving the study, whereas another developed cryptococcal meningoencephalitis during the course of the study. Opportunistic necropsies on ten antigen-positive koalas resulted in discovery of small cryptococcal lesions in two (paranasal sinus and lung, respectively). Our data suggest that cryptococcal antigenaemia occurs commonly in koalas, especially in areas with a high environmental presence of C n. var. gattii. Subclinical disease appears most likely to manifest as a small focal lesion in the respiratory tract. Possible outcomes include elimination by an effective immune response, quiescence with possibility of later re-activation or direct progression to overt disease. Symptomatic and subclinical cases showed differences in levels of antigenaemia. The data presented have significant implications for koalas in captivity.

Cutaneous xanthomas with concurrent demodicosis and dermatophytosis in a cat.

Multiple cutaneous xanthomas, associated with fasting hyperlipidaemia, are described in a 9-month-old domestic long-haired cat. A severely pruritic, papular, and crusting dermatitis affecting the head and neck, initially diagnosed as lesions of the eosinophilic granuloma complex, progressively developed on the head and pinnae. Pruritus was controlled with administration of prednisolone and chlorambucil. Repeat histological examination confirmed the diagnosis of cutaneous xanthoma and concurrent mild demodicosis. Marked fasting hypercholesterolaemia, hypertriglyceridaemia and transient hyperglycaemia were subsequently confirmed. Treatment for hyperlipidaemia and xanthomas with a low-fat diet (Hill's Feline r/d) and the previously unreported treatment for feline demodicosis of daily oral milbemycin were commenced. Multiple pink, alopecic plaques and papules gradually regressed, however pruritus recurred if immunosuppressive treatment was reduced, and well-demarcated areas of alopecia developed on the head, limbs and trunk, despite negative skin scrapings for demodex mites. Fungal culture of hair samples yielded Microsporum canis. All cutaneous lesions resolved with the addition of griseofulvin to the treatment regimen. Concurrent corneal ulceration and keratoconjunctivitis sicca ultimately resolved with treatment, including topical cyclosporin. Diabetes mellitus developed 6 months after resolution of skin lesions. No cutaneous or ocular abnormalities were present 6 months later with continued low-fat diet and insulin administration, although transient recurrence of papules and pruritus occurred after inadvertent access to a fatty meal. An underlying primary hyperlipidaemia was suspected, causing pruritic xanthomas. This may represent the first report of concurrent cutaneous xanthomas, demodicosis and dermatophytosis in a cat.

Simian immunodeficiency virus infections in vervet monkeys (Clorocebus aethiops) at an Australian zoo.

A number of monkey species, including African green monkeys and African vervet monkeys (Chlorocebus aethiops), are frequently infected in the wild and in captivity with a Simian immunodeficiency virus strain, SIVagm, a primate lentivirus. Up to 50% of African green monkeys are estimated to be infected with SIVagm. SIV strains are very closely related to HIV-2 strains, which are a cause of AIDS in humans, predominantly in western Africa, although cases in Australia have also been reported. It is generally thought that SIV is non-pathogenic in several natural hosts, including African green monkeys. Nevertheless many SIV strains induce a profound immunodeficiency virtually identical to HIV-1 induced AIDS in humans when administered to Asian macaque species such as rhesus (Macaca mulatta) or pigtailed macaques (M nemestrina). SIV infection of Asian macaque species is frequently employed as an animal model for AIDS vaccine studies. In November 1996 a group of 10 African vervet monkeys were imported from the USA for display at Victoria's Open Range Zoo in Werribee. Two animals in this group of monkeys later developed a fatal gastroenteric illness. These diagnoses led us to initiate SIV testing of the colony.

The use of compound 48/80 and codeine phosphate as positive controls for intradermal skin testing in dogs.

The mast cell secretagogues compound 48/80 and codeine phosphate were evaluated as potential positive controls for intradermal skin testing in dogs. Wheal responses to both agents were compared with responses to histamine and saline in 11 normal dogs, and were strong and not significantly different from histamine responses in nine dogs (P < 0.01), and significantly weaker than histamine in two dogs (P < 0.05). Wheal responses to compound 48/80 (1 mg mL-1) were evaluated in 82 suspected atopic dogs and were similar to histamine in 79 dogs and markedly weaker than histamine in three dogs. Of nine confirmed atopic dogs with weak responses to injected allergens, seven had strong responses to compound 48/80, and eight had strong responses to histamine. Compound 48/80 and codeine phosphate appear unreliable positive controls for skin testing in normal dogs. Compound 48/80 (1 mg mL-1) may be a reliable positive control in atopic dogs but is a poor indicator of skin reactivity to allergens.

An undescribed Demodex sp. and demodicosis in a captive koala (Phascolarctos cinereus).

A 12-yr-old male koala (Phascolarctos cinereus) in a zoo collection developed bilateral, noninflammatory, periocular alopecia. Deep periocular skin scrapings yielded multiple adult, nymphal, and larval mites of a previously undescribed Demodex species. Skin biopsies from affected areas revealed multiple mites in superficial keratin and within hair follicles, associated with a mild intramural lymphocytic folliculitis. Treatment with daily oral ivermectin was safe and effective. Although Demodex sp. are previously reported from skin scrapings in another koala with periocular alopecia, this is the first confirmed case of koala demodicosis.

Experimental reproduction of viral chorioretinitis in kangaroos.

OBJECTIVE: To investigate whether preparations containing Wallal and/or Warrego viruses could cause disease when inoculated subcutaneously into captive kangaroos. DESIGN AND PROCEDURE: Four groups of two kangaroos, seronegative to both Wallal and Warrego virus, were each inoculated with wild Wallal virus, cultured Wallal virus, wild Warrego virus, or wild Warrego virus followed by wild Wallal virus after 3 weeks. A single uninoculated animal served as a control. Animals were monitored weekly under anaesthesia, examined ophthalmoscopically (including fundic photography), and samples collected for haematological and serum biochemical analysis, virus isolation, PCR and serological examination for antibodies against Wallal and Warrego viruses. Animals inoculated with cultured Wallal virus were killed at week 10, and remaining kangaroos were reinoculated with cultured Wallal virus at week 12. RESULTS: Virus was isolated from the blood of two kangaroos 2 weeks after inoculation with Wallal virus preparations, and from a third kangaroo 2 weeks after reinoculation. By 3 weeks after inoculation, all kangaroos given Wallal virus preparations had seroconverted to Wallal virus and one had seroconverted to Warrego virus. Fundic changes were detected in the three viraemic kangaroos 4 or more weeks after inoculation, and lesions were present in the eye and brain typical of those seen in field cases of chorioretinitis. No other kangaroos had lesions. Wallal virus was identified by PCR and immunohistochemical analysis in the retina of one affected animal and orbivirus-like particles were seen by electron microscopy in the remains of retinal cells. CONCLUSION: The condition of chorioretinitis was reproduced in three of eight kangaroos by inoculation with preparations containing Wallal virus.

Surgical management of an abdominal abscess in a Malayan tapir.

A captive Malayan tapir was observed to have inappetence, weight loss, signs of depression, mild dehydration and diarrhoea. Haematological and serum biochemical tests showed anaemia, hypoproteinaemia, hyperfibrinogenaemia and neutrophilia with a left shift. Ultrasonic examination of the abdomen under anaesthesia revealed a well-encapsulated abscess. The abscess was marsupialised to the ventral body wall. Culture of the pus produced a mixed bacterial growth. Antimicrobial therapy was based on bacterial sensitivity results. Follow-up ultrasonic examinations showed resolution of the abscess. Ninety-one days after surgery the tapir began regurgitating food and water. An abscess originating from the stomach and occluding the lumen of the duodenum was identified at surgery. The abscess ruptured during surgical manipulations and the tapir was euthanased.