CONTRAST-ENHANCED COMPUTED TOMOGRAPHIC IMAGING OF THE AUDITORY TUBE IN MESATICEPHALIC DOGS

Computed tomography after contrast medium injection was performed in three mesaticephalic canine cadavers to image the auditory tube. Cadavers were positioned in lateral recumbency for imaging. A myringotomy incision was made in the left tympanic membrane of each dog, and contrast medium was infused into the ear canal and middle ear through a balloon-tip catheter. With this method, contrast medium filled the left bulla and auditory tube in all three cadavers. Computed tomography following contrast medium injection was effective for evaluation of the canine auditory tube. Future studies are required to determine the usefulness, as well as the safety, of this procedure in the evaluation of the auditory tube in other breeds of dogs as well as dogs with otitis     

IMAGING DIAGNOSIS—BACTERIAL DISKOSPONDYLITIS IN A GOAT

A 3-year-old intact male Boer goat was evaluated for paraplegia. Computed tomography (CT) indicated the presence of diskospondylitis, which had previously not been reported in this species, and significant compressive myelopathy. Chronic bacterial pneumonia, epididymitis, nephritis, and soft-tissue abscesses were believed to result in hematogenous spread of bacteria to the affected disk spaces. Staphylococcus spp. and Archanobacterium pyogenes were both identified from postmortem cultures of the vertebral column.     

Seizures during medetomindine sedation and local anaesthesia in two dogs undergoing skin biopsy

Each of two dogs presented for multiple skin biopsies were sedated with intravenous medetomidine and lignocaine was injected subcutaneously to provide local anaesthesia for skin biopsy. One dog had a seizure during skin biopsy and again immediately following reversal of medetomidine with atipamezole. The other dog developed seizures 2 h following skin biopsy at which time the medetomidine was reversed with atipamezole. Both dogs were neurologically normal with no history of seizures prior to the procedure and remained neurologically normal for 14 weeks and 9 months, respectively, following the procedure. A drug interaction between the α₂-adrenergic agonist medetomidine and lignocaine is suspected and highlights the potential for seizures following the subcutaneous administration of relatively large doses of lignocaine under medetomidine sedation.     

The laboratory culture of Dichelobacter nodosus in a footrot eradication program

SUMMARY As part of a program to eradicate virulent footrot from Western Australia, 2745 isolates of Dichelobacter nodosus were isolated from 5263 specimens from 1883 submissions. The virulence of each isolate was assessed using protease thermostability and isoenzyme zymogram. We describe changes to the materials and methods required to handle these specimens and to reduce the interval between submission and report to 8 days.     

Using a GnRH agonist to obtain an index of testosterone secretory capacity in the cockatiel (Nymphicus hollandicus) and sulphur-crested cockatoo (Cacatua galerita)

Objective   Validation of a stimulation test for determining the steroidogenic capacity of the parrot testis. The major aim was to characterise testosterone secretion after injection of a gonadotropin-releasing hormone agonist (GnRHa), then use the test to investigate seasonal reproduction in the male cockatiel.
Procedure   A synthetic GnRHa (buserelin; 8.0 µg of peptide/kg bodyweight) was injected IM into male cockatiels (n = 7) and sulphur-crested cockatoos (n = 3) and serial blood samples collected at 0, 30, 60, 90 and 120 min after administration. Once validated, the technique was subsequently used to examine seasonal changes (23 months) in the testosterone profile of a captive cockatiel population.
Results   Injection of buserelin resulted in a significant increase in the testosterone concentration of cockatiel plasma, with maximal concentrations occurring at approximately 60 (1.33 ± 0.08 ng/mL) to 90 min (1.22 ± 0.08 ng/mL) after injection. Although no clear pattern of seasonal variation in testosterone secretion was detected in cockatiel plasma, samples taken 60 and 90 min after administration showed a significant increase in all seasons. Injection of buserelin in the sulphur-crested cockatoo also resulted in increased testosterone secretion, with maximal concentrations obtained after 90 min.
Conclusion   Buserelin can be used to obtain a reliable index of the prevailing testosterone capacity of the cockatiel and cockatoo testis. With further studies, this test may be incorporated into clinical assessment of reproductive status.     

Immunophenotypic and histological characterisation of 109 cases of feline lymphosarcoma

OBJECTIVE: To determine and analyse the immunophenotype and histological appearance of naturally occurring cases of lymphosarcoma in Australian cats. DESIGN: A prospective multi-institutional study of naturally occurring feline lymphosarcoma. METHODS: One hundred and eighteen cats were referred for diagnosis and/or management of suspected lymphosarcoma. Tissue samples for histopathological analysis and immunophenotyping were collected as biopsies or at necropsy from 109 cases. Histological classification of the neoplasms followed the Working Formulation Classification System. Four multi-species cross-reactive antibodies were used to classify tumours as having a B or T cell phenotype. RESULTS: Seventy-six (70%) cases were B cell tumours and 28 (26%) were T cell tumours. The remaining 5 (4%) specimens failed to stain with the four antibodies. Histologically, 11 (10%) cases were classified as low-grade, 72 (66%) were medium-grade and 26 (24%) were high-grade tumours. There were no significant associations between age and either histological grade or immunophenotype. Mediastinal and leukaemic cases were significantly more likely to be T cell tumours (P < 0.001 and P < 0.001, respectively). CONCLUSIONS: In contrast to previously documented studies in the cat, the majority of cases of lymphosarcoma were of B cell phenotype and intermediate histological grade. Based on our data, the histological phenotype of lymphosarcoma is unlikely to predict immunotype, nor are cases of certain immunotypes likely to be of specific histological subtype. Considered in relation to previous reports, the findings suggest that epidemiological factors operating in these cats to produce lymphosarcoma may be different to those operating in North American and UK cat populations.     

Cochlosoma infections in finches

Objective To survey finches in pet shops for Cochlosoma infection and evaluate the efficacy of antiprotozoal therapy with metronidazole or ronidazole.
Design A survey of pet shop finches and drug efficacy trials.
Procedure Finches in pet shops were randomly selected and their faeces examined microscopically for motile Cochlosoma sp trophozoites. Drug trials were carried out on 60 adult finches with naturally occurring infections. Body weight was measured and the faeces of each bird was examined for trophozoites at the beginning and 7 days after the end of treatment. In some birds, additional daily faecal examinations were done until three consecutive negative results were obtained. Metronidazole was administered at various dose rates by crop gavage or in drinking water to eight groups of five to ten finches each. Ronidazole was given in water for 7 days to ten finches. In addition, six finches whose faeces tested positive were necropsied and their tissues collected for histological examination.
Results Motile flagellates in the faeces were identified as C anatis -like protozoa. Red-headed parrot-finches, Bengalese and Lady Gould finches were found to be most commonly infected. Cochlosoma sp was also found in the blue-faced parrot-finch, zebra finch, painted finch, nutmeg mannikin and double-barred finch. Metronidazole and ronidazole were found to be effective against Cochlosoma sp. Histological findings on infected adult finches were normal, except for the presence of numerous flagellates between the colorectal villi and cloacal mucosal folds.
Conclusions Cochlosoma anatis -like organisms can infect several species of finches and in adult finches are confined to the colorectum and cloaca. Infection in adult finches was mostly subclinical and could be treated effectively with metronidazole or ronidazole.     

Prevalence of megabacteria in budgerigar colonies

Objective To measure the prevalence of megabacteria in budgerigar-breeding colonies and to evaluate possible methods to reduce the prevalence.
Design A monitoring study over several years.
Sample population Two budgerigar ( Melopsittacus undulatus ) colonies with over 300 birds each.
Procedure The prevalence of megabacteria in the faeces in two budgerigar breeding colonies, colony 1 and 2, was determined by faecal examination of each bird. Following an initial survey (1990), most of the birds that were scored 2+ or more were culled and a management practice was implemented to discriminate against positive birds. Consecutive yearly surveys (1991, 1992) were conducted on the young birds bred in these colonies. The prevalence of megabacteria in colony 2 was also evaluated in 1994 and 1996 after all the birds were treated with amphotericin B administered in drinking water.
Results The prevalence of megabacteria in the two colonies was significantly (P < 0.001) different. Overall the prevalence of megabacteria adjusted for colony differences was significantly higher (P < 0.025) in males compared to females. Age was not an influencing factor. After the initial survey, the prevalence in the offspring did not significantly (P > 0.05) decrease in the following two annual breeding seasons but by inference it did significantly decrease after amphotericin B treatment.
Conclusion The practice of culling most birds with more megabacteria in faeces and discriminating against positive birds when selecting birds for breeding or culling birds on show quality does not decrease megabacteria prevalence in the offspring. However, a reduction in prevalence does occur with administration of amphotericin B. Birds may have amphotericin B-resistant organisms and these birds need to be identified and culled.