Toxoplasma gondii inclusions in peripheral blood leukocytes of a red-necked wallaby (Macropus rufogriseus)

Abstract A 2-year-old, male, red-necked (Bennett's) wallaby ( Macropus rufogriseus ) from a zoological facility was presented for peracute onset of severe depression, unresponsiveness, ataxia, and loose feces. Serum biochemical abnormalities included azotemia, hypoalbuminemia, increased alanine aminotransferase activity, hyperbilirubinemia, hyperphosphatemia, and hyperkalemia, consistent with multi-organ system failure. Severe thrombocytopenia suggested possible disseminated intravascular coagulation. Peripheral blood smear examination revealed numerous ovoid, protozoal inclusions within monocytes and occasionally within neutrophils. Despite aggressive supportive therapy, the patent died within 5 hours of presentation. Gross necropsy and histopathologic findings included severe multifocal necrotizing lesions in multiple organs. Numerous intralesional protozoal organisms were observed and were identified as Toxoplasma gondii by immunohistochemistry. Macropods (wallabies and kangaroos) are known to be highly susceptible to toxoplasmosis, with high mortality rates; diagnosis most often is obtained at necropsy. Detection of protozoal organisms in peripheral blood leukocytes is reported rarely and has not been documented previously in a macropod. Parasitemia in this case was attributed to severe, disseminated disease. Careful examination of peripheral blood smears in macropods suspected of toxoplasmosis may be warranted.     

Pharmacokinetics of oxytetracycline in clinical cases in the red-necked wallaby (Macropus rufogriseus)

Oxytetracycline, administered at 40 mg kg-1 by intravenous injection, was used as part of the treatment of three female red-necked wallabies, Macropus rufogriseus, with suspected Fusobacterium necrophorum infections. The plasma concentrations of this drug in blood samples collected at intervals up to 24 hours after administration were measured using a biological assay. The pattern of decline in plasma oxytetracycline concentration with time was consistent with a two-compartment model. The half-life of the elimination phase was calculated to be 11.4 hours and the apparent volume of distribution was found to be 2.041 litres kg-1. These results provide a basis for devising appropriate oxytetracycline dosage regimes for the species.     

Methane production by red-necked wallabies (Macropus rufogriseus)

The claimed low production of CH(4) by kangaroos and marsupials in general has been questioned because of a lack of data. The extent of their CH(4) production is of interest both from the point of view of discussing meat production of marsupials and as a basis for developing methods to reduce CH(4) production from ruminants. In the present experiment, the CH(4) production of 8 red-necked wallabies (Macropus rufogriseus) was measured of which 4 were fed 2 different diets in an open-circuit respiration chamber. These results were compared with a newly developed, inexpensive, and simple method that does not influence the behavior of the animal, and where the ratio between CH(4) and CO(2) is measured and used together with the calculated CO(2) to quantify the CH(4) production. The experiment demonstrated that the wallabies produce CH(4). However, the amount of CH(4) produced by these wallabies was between 1.6 and 2.5 L/d equivalent to 1.6 and 2.5% of GE or 2.2% and 3.5% of DE intake and 0.22 L/BW, kg(0.75). This is between 25 and 33% of what can be expected from ruminants fed the same diet. Based on the uneven release of CH(4) with time, it is most likely that the CH(4) is excreted through flatulence and not through breathing as is seen in ruminants. The experiments also showed that a reasonably accurate determination of the CH(4) production of a group of animals can be obtained by simply measuring the CH(4)/CO(2) ratio over a limited time span. This may represent the situation in a natural setting better than measurements in a respiration chamber. It was found that the CH(4)/CO(2) ratio in itself represents a reasonable prediction of the proportion of feed GE that is lost as CH(4), and that this method offers new opportunities for CH(4) measurements on a large number of animals.     

On the clinical chemistry of the Bennett's wallaby (Macropus rufogriseus rufogriseus)

The following parameters were determined in blood serum of apparently healthy Bennett's wallabies (Macropus rufogriseus) using the Hitachi 917 (Roche Diagnostics, Mannheim, Germany) and/or the Vettest 8008 (IDEXX-GmbH, Woerrstadt, Germany): alkaline phosphatase, alanine aminotransferase, ammonia, alpha-amylase, aspartate aminotransferase, Ca, Cl, cholesterol, cholinesterase, creatine kinase, creatinine, gammaglutamyltransferase, glucose, iron, lactate dehydrogenase, magnesium, phosphate, potassium, protein, sodium, total bilirubin, triglyceride, and urea. The results for cholesterol, glucose, total protein, triglyceride and for the enzymes alanine aminotransferase, alkaline phosphatase, aspartate aminotransferase, gamma-glutamyltransferase and lactate dehydrogenase differed significantly between both methods (P < 0.05). There is a negative correlation between the age of the Bennett's wallabies and the activity of the alkaline phosphatase. Five protein fractions could be separated on cellulose acetate electrophoresis. The mean concentrations of fructosamine and beta-hydroxybutyrate were 447.3 micromol/L and 0.27 mmol/L, respectively. The estimated vitamin A intake had no influence on the vitamin A concentration in serum. The serum vitamin E concentration was in general low and vitamin E was below the detection limit of 0.82 micromol/L in 29 out of 42 serum samples. The use of these analytes is discussed concerning the knowledge about the physiology, nutrition and diseases of macropods.     

Use of antibiotic impregnated polymethylmethacrylate beads for the treatment of chronic mandibular osteomyelitis in a Bennett's wallaby (Macropus rufogriseus rufogriseus)

Antibiotic impregnated polymethylmethacrylate beads were surgically implanted into the mandible of an adult Bennett's wallaby (Macropus rufogriseus rufogriseus) suffering from chronic mandibular osteomyelitis that had proven refractory to systemic antibiotic treatment. Although a discrete inflammatory mass remained, clinical signs of inappetance and a discharging sinus were alleviated following implantation of the beads. This procedure resulted in a more satisfactory outcome than other methods of treatment used previously for this condition and avoided the problems associated with regular handling and prolonged medication.     

Toxoplasmosis in captive Bennett's wallabies (Macropus rufogriseus) in Argentina

Wallabies and other Australian marsupials are among the most susceptible species to Toxoplasma gondii. Fatal generalized toxoplasmosis was diagnosed in two captive 3 year-old female Bennett's wallabies (Macropus rufogriseus) from Argentina (w 1 and w 2) with a history of sudden death. Both animals had internal joeys which died 2 days after their mothers. Serologically, both females and one adult male without clinical signs from the same enclosure (w 3) had antibody titers for T. gondii>or=800 by the modified agglutination test (MAT); another adult male (w 4) was negative (MAT titer<25). Microscopically, tachyzoites were observed associated to non-suppurative meningoencephalitis, hepatitis, myositis, myocarditis and severe enteritis in hematoxylin and eosin stained sections from both w 1 and w 2. Immunohistochemically, parasites in heart, brain and liver sections of both female wallabies reacted with T. gondii antiserum. T. gondii was isolated from brain tissues of w 1 and w 2 by bioassay in mice and by culture in bovine monocytes and both isolates were cryopreserved. Genomic DNA was isolated from tachyzoites grown in cultures derived from both animals. The primer pair B22/B23 specific for T. gondii produced 115bp amplicons on poliacrylamide electrophoretic gels. Stray cats were suspected as the possible source of infection. Not all infected macropods were ill, showing that the infection may be asymptomatic and is not always fatal. A vertical infection could not be proved in the joey from w 2. As far as we know, this is the first confirmed report of toxoplasmosis in Bennet's wallabies in Argentina.     

First description of onychomycosis caused by Chrysosporium keratinophilum in captive Bennett's wallabies (Macropus rufogriseus rufogriseus)

Seven Bennett's wallabies (Macropus rufogriseus rufogriseus) presented within a period of several months with onychodystrophy, onychomadesis, and severe digital tumefaction. Histopathologic findings included a pseudocarcinomatous hyperplasia of the claw matrix surrounding a cavity filled with keratin and septate hyphae stained with periodic acid Schiff reagent. The fungal species Chrysosporium keratinophilum was identified on cultures. The wallabies were orally treated with ketoconazole (15 mg/kg s.i.d.) for 20 wk. Material and enclosures were cleaned and sprayed with 0.2% enilconazole solution once a month over a period of 4 mo. No improvement of advanced cases was observed, but no new case appeared for the next 6 mo. The positive mycological culture and the invasion of tissues on histopathologic examination suggested that the fungal species C. keratinophilum was implicated in this claw disease. This is the first report of onychomycosis caused by C. keratinophilum in animals.     

Pharmacokinetics of intravenous clindamycin phosphate in captive Bennett's wallabies (Macropus rufogriseus)

This study was designed to investigate the pharmacokinetics of clindamycin, a lincosamide antibiotic, in Bennett's wallabies. The pharmacokinetic properties of a single intravenous (IV) dose of clindamycin were determined in six wallabies. A single 20‐min IV infusion of 20 mg/kg of clindamycin was administered, followed by blood collection prior to, and up to 12 hr after clindamycin administration. Plasma clindamycin concentrations were determined by high‐pressure liquid chromatography (HPLC) with ultraviolet (UV) detection. Pharmacokinetic variables were calculated using a two‐compartment model with first order elimination which best fit the data. The mean volume of distribution at steady‐state, distribution half‐life, and elimination half‐life were 898.25 ml/kg, 0.16 hr, 1.79 hr, respectively. No adverse effects were noted after IV administration.     

Gastric amebiasis due to Entamoeba histolytica in a Dama wallaby (Macropus eugenii)

A 1.5-year-old captive female Dama wallaby (Macropus eugenii) died after a 3-month period of progressive weight loss, anorexia, bloat, and diarrhea. Histopathologic examination revealed numerous Entamoeba histolytica trophozoites within the gastric mucosa and, less frequently, gastric submucosa and submucosal vessels. Immunofluorescent antibody testing confirmed the identity of the trophozoites as E. histolytica. The trophozoites were associated with mild glandular epithelial necrosis, mucosal erosions, and lymphoplasmacytic inflammation. E. histolytica most commonly causes necrotizing and ulcerative colitis in humans and captive nonhuman primates, and it causes necrotizing and ulcerative gastritis in nonhuman primates with sacculated stomachs adapted for leaf fermentation. Rare cases of gastric amebiasis also have been been reported in captive macropods, which also have complex sacculated stomachs. To our knowledge, this is the first report confirming E. histolytica as the cause of gastric amebiasis in a wallaby. The zoonotic potential of this infection in macropods is uncertain.     

Evaluation of medetomidine-alfaxalone and medetomidine-ketamine in semi-free ranging Bennett's wallabies (Macropus rufogriseus)

Twenty-six adult semi-free-ranging Bennett's wallabies were anesthetized. Animals in group MA received medetomidine 0.1 mg/kg and alfaxalone 4 mg/kg i.m. in a 5-ml dart, whereas those in group MK received medetomidine 0.1 mg/kg and ketamine 5 mg/kg i.m. in a 3-ml dart. Dosages were based on estimated body weights. The wallabies were allowed to recover spontaneously or, if still nonresponsive at the end of the procedure, were given atipamezole 0.5 mg/kg (half the dose via i.m. and the other half via i.v.). Heart rate and respiratory rate were monitored at 5-min intervals, temperature at 10-min intervals, and two arterial blood samples were taken for blood gas analysis. Statistical analysis was performed by using analysis of variance (P < 0.05). The use of 5-ml darts in group MA compared with 3-ml darts in group MK could potentially increase the risk of iatrogenic trauma and should be considered. Induction and maintenance of anesthesia were satisfactory in both groups. There were no significant differences between the groups in mean time to first effect, recumbency, and approach, or to time to sternal recumbency and standing after reversal with atipamezole. Although bradycardia was present in both groups, no statistical differences were calculated for respiratory rate and heart rate, whereas the mean cloacal temperature was significantly lower in group MA (P = 0.01). Mixed acid-base disturbances occurred in both groups. All but one animal in group MK needed atipamezole at the end of the procedure. No adverse effects were observed after recovery.     

Cuterebra myiasis in a group of red kangaroos (Megaleia rufa), a Bennett's wallaby (Macropus rufogriseus fruticus), and a Gunther's dik dik (Maloqua guentheri smithi).

A group of four red kangaroos (Megaleia rufa), a Bennett's wallaby (Macropus rufogriseus fruticus), and a Gunther's dik dik (Maloqua guentheri smithi) were presented over a 2-mo period with draining lesions over the thorax or on the lateral aspect of a hind leg. Only one animal exhibited more than one lesion. Physical examinations revealed infections with fly larvae. The parasites were manually removed and identified as Cuterebra spp. All of the affected animals survived, with no apparent side effects.     

Comparison of three anaesthetic protocols in Bennett’s wallabies (Macropus rufogriseus)

ObjectiveInvestigate physiological and sedative/anaesthetic effects of xylazine, medetomidine or dexmedetomidine combined with ketamine in free-ranging Bennett's wallabies.Study designProspective clinical trial.AnimalsTwenty-six adult free-ranging Bennett's wallabies.MethodsAnimals were darted intramuscularly with one of three treatments: xylazine and ketamine, 2.0 and 15.0 mg kg^?1, respectively (XK): medetomidine and ketamine 0.1 and 5.0 mg kg^?1 (MK) and dexmedetomidine and ketamine 0.05 and 5.0 mg kg^?1 (DMK). Body weights were estimated. If the animal was still laterally recumbent after 45 minutes of anaesthesia, then an alpha-2 adrenoceptor antagonist, atipamezole, was administered (XK: 0.4 mg kg^?1, MK: 5 mg kg^?1, DMK: 2.5 mg kg^?1). Heart rate (HR) and respiratory rate (f_R) were recorded at 5-minute intervals and temperature at 10-minute intervals. Venous blood was taken 30 minutes after initial injection. Statistical analysis utilized anova. p < 0.05 was considered significant.ResultsAnimals became recumbent rapidly in all groups. XK animals had muscle twitches, responded to external stimuli, and three animals required additional dosing; this was not observed in the MK and DMK groups. HR (mean ± SD beats minute^?1) in XK (81 ± 4) was significantly higher than MK (74 ± 2) and DMK (67 ± 4). There were no differences in f_R, temperature, blood-gas and biochemical values between groups. More animals in MK (9/10) and DMK (5/6) needed antagonism of anaesthesia compared with XK (1/10). There were no adverse effects after anaesthesia.Conclusion and clinical relevanceCardio-respiratory effects were similar in all groups. There were fewer muscle twitches and reactions to external stimuli in MK and DMK. Duration of anaesthesia was shorter in XK; most animals in MK and DMK needed atipamezole to assist recovery. All three treatments provided satisfactory sedation/anaesthesia and are suitable for use in Bennett's wallabies.     

Familial ichthyosiform keratoderma in newly out-of-pouch Bennett's wallabies (Macropus rufogriseus) and report of two cases

Primary inherited disorders of cornification in veterinary medicine are uncommon and rarely reported. Herein described is a unique syndrome associated with keratoderma that occurred in two Bennett's wallaby siblings (Macropus rufogriseus), and was characterized by profound thickening of the pad skin of all feet, generalized scaling of haired skin, and death within 7 weeks of out-of-pouch experience. The male also had depressed serum zinc levels. In addition, the male had, on electron microscopic exam of his skin, the presence of abnormal lipid deposits within the stratum corneum and stratum granulosum. The combination of clinical features and electron microscopic findings strongly suggests a syndrome analogous to harlequin ichthyosis or lamellar ichthyosis in humans.     

Nasal myiasis in a cat caused by larvae of the nasal bot fly, Oestrus ovis

An 8-year-old desexed male Burmese cat, which lived on a sheep-grazing property in central New South Wales, Australia, was presented following the sudden onset of dyspnoea, moist coughing and violent sneezing. The respiratory distress started several hours after the cat had made an outdoor excursion. Anterior rhinoscopy demonstrated small, white objects moving across oedematous and moderately inflamed nasal mucosa. These were retrieved via a series of vigorous nasal flushes and subsequently identified as larvae of the nasal bot fly, Oestrus ovis. The cat was treated with ivermectin followed by selamectin 7 days later. It went on to make a complete recovery over 2-3 weeks.     

Sub-cellular localisation of alkaline phosphatase activity in the cytoplasm of tammar wallaby (Macropus eugenii) neutrophils and eosinophils

Alkaline phosphatase (ALP) has been used in studies of neutrophil morphology and function as a marker for identifying different granule populations. In human neutrophils, ALP is found within secretory vesicles, a rapidly mobilisable vesicle population important for upregulating membrane receptors during early activation. Intra-cellular ALP activity in the heterophils of rabbits and guinea pigs, in contrast, is found only in secondary granules. The neutrophils and eosinophils of tammar wallabies (Macropus eugenii) have previously been reported to contain large amounts of ALP activity when stained using routine cytochemical techniques. To define the subcellular location of ALP in this species, cell suspensions were examined using cerium chloride cytochemistry and transmission electron microscopy (TEM). ALP was found in 2 distinct cytoplasmic compartments. One compartment displayed morphology consistent with a subpopulation of secondary granules while a second tubulo-vesicular population appeared similar to the secretory vesicles of human neutrophils. Thin tubular vesicles containing ALP were also identified within the cytoplasm of tammar wallaby eosinophils. Large numbers of ALP-containing vesicles have not been recognised previously in eosinophils and this may represent a novel cytoplasmic compartment. In both cell types, ALP-containing structures showed alteration in morphology following stimulation with N-formyl-Met-Leu-Phe (fMLP) and PMA.