TUBERCULOSIS AND BRUCELLOSIS IN WOOD BISON (BISON BISON ATHABASCAE) IN NORTHERN CANADA: A RENEWED NEED TO DEVELOP OPTIONS FOR FUTURE MANAGEMENT.

Effective, long-term strategies to manage the threat of bovine tuberculosis and brucellosis spillback from northern, diseased bison to the Canadian cattle herd and adjacent disease-free wood bison (Bison bison athabascae) herds have eluded policy makers in recent decades. A controversial plan to depopulate infected herds and repopulate them with disease-free wood bison was rejected in 1990 because of significant public concern. Since then, technical advances in vaccine technology, genetic salvage, selective culling, and diagnostic test development have occurred. Containment strategies to reduce further spread of these diseases are a necessary first step; recent progress has been made in this area, but challenges remain. This progress has produced more options for management of these herds in northern Canada, and it is time to consider wood bison conservation and long-term disease eradication as equally important goals that must satisfy concerns of conservation groups, agriculture sectors, aboriginal groups, and the general public. Management of wildlife disease reservoirs in other areas, including Yellowstone and Riding Mountain national parks, has demonstrated that effective disease management is possible. Although combinations of different strategies, including vaccination, genetic salvage techniques, and selective culling, that use sensitive and specific diagnostic tests may offer alternatives to depopulation/repopulation, they also have logistic constraints and cost implications that will need consideration in a multistakeholder, collaborative-management framework. We feel the time is right for this discussion, so a long-term solution to this problem can be applied.

A retrospective study of non-suppurative encephalitis in beef cattle from western Canada.

Non-suppurative encephalitis occurs sporadically in beef cattle in western Canada, leading to loss of animals. This retrospective study investigated the presence of viral, bacterial, and protozoal antigens or DNA in 37 western Canadian feedlot cattle with non-suppurative encephalitis for which a cause had not been identified. Cases were selected based on the age of the animal (> 7 months), and clinical history of recumbency and depression. The identification of rabies in 1 case stresses the importance of including this viral disease in the list of differential diagnoses. Because there was variation in the severity, distribution, and type of lesions, it is possible that there may be more than 1 cause, but failure to identify an infectious agent might also suggest that non-infectious agents could play a role.

Étude rétrospective de l'encéphalite non suppurative chez les bovins de boucherie de l'Ouest canadien. L'encéphalite non suppurative se produit sporadiquement chez les bovins de boucherie de l'Ouest canadien, ce qui cause une perte d'animaux. Cette étude rétrospective a fait enquête sur la présence d'antigènes viraux, bactériens et protozoaires ou d'ADN dans 37 parcs d'engraissement de l'Ouest canadien atteints de l'encéphalite non suppurative dont la cause n'avait pas été identifiée. Les cas ont été choisis en fonction de l'âge de l'animal (> 7 mois) et de l'anamnèse clinique de décubitus et de dépression. L'identification de la rage dans 1 cas met en lumière l'importance d'inclure cette maladie virale dans la liste des diagnostics différentiels. Parce qu'il y avait une variation au niveau de la gravité, de la répartition et du type de lésions, il est possible qu'il y ait plus d'une cause, mais la non-identification d'un agent infectieux pourrait aussi suggérer que des agents non infectieux pourraient jouer un rôle.(Traduit par Isabelle Vallières).

Description of the larva of Ceratophyllus vagabundus vagabundus (Siphonaptera:Ceratophyllidae) from nests of Ross's and lesser snow geese in Nunavut, Canada.

Adults of the flea, Ceratophyllus vagabundus vagabundus , were present in the hundreds in nests of Ross's (Chen rossii) and lesser snow (Chen caerulescens caerulescens) geese in the Arctic goose colony at Karrak Lake, Nunavut, Canada. Ceratophyllus v. vagabundus had not been previously recorded in association with Ross's or snow geese. Large numbers of C. v. vagabundus adults and larvae were collected and a description of the larva is provided for the first time. On the basis of external characters, larvae were indistinguishable from those of a number of other Ceratophyllus spp. previously described from North America, i.e., Ceratophyllus idius, Ceratophyllus niger, and Ceratophyllus lari.

An outbreak of bovine tuberculosis in an intensively managed conservation herd of wild bison in the Northwest Territories.

An outbreak of bovine tuberculosis was detected in the Hook Lake Wood Bison Recovery Project captive-breeding herd in March 2005. This study investigates the most likely source of Mycobacterium bovis and identifies difficulties associated with salvaging tuberculosis-free animals from an endemically infected herd.

Naturally acquired feline immunodeficiency virus (FIV) infection in cats from western Canada: Prevalence, disease associations, and survival analysis.

This retrospective study evaluated epidemiologic features and disease associations of feline immunodeficiency virus (FIV) infection in client owned cats from western Canada. Among 1205 cats that were tested 66 (5.5%) were positive for FIV antibody (FIV(+)) with a higher prevalence in males than females. FIV(+) cats were older than the overall population. Epidemiologic features and disease associations were compared between 58 FIV(+), but feline leukemia virus negative (FeLV(-)) cats and 58 age and sex matched FIV-negative (FIV(-)), FeLV(-) cats. FIV positivity was associated with a history of bite wounds, increasing age, and male gender. Lethargy and oral diseases were significantly associated with FIV positivity. Although several FIV(+) cats were euthanized, the survival time of FIV(+) cats after diagnosis was not significantly different from that of FIV(-) cats. In summary, FIV prevalence was low in cats from western Canada, clinical signs/diseases were mild, and lifespan was not different in FIV(+) cats.

Systemic infection with Mortierella wolfii following abortion in a cow.

Severe meningoencephalitis and endometritis associated with necrotizing vasculitis, thrombosis, and infarction were found at necropsy of a 4-year-old Aberdeen Angus cow with a history of abortion and neurological signs. Focal pyogranulomatous pneumonia and nephritis were also present. Fungal hyphae typical of zygomycetes were abundant within lesions, and Mortierella wolfii was cultured from multiple tissues. This is believed to be the first report of systemic mortierellosis following abortion in North America, and the second reported instance of encephalitis caused by M. wolfii in a cow.

An outbreak of West Nile virus infection in captive lesser scaup (Aythya affinis) ducklings.

This report describes West Nile virus (WNV)-associated mortality in captive lesser scaup (Aythya affinis) ducklings that occurred in Saskatchewan, Canada, in July and August 2007. There were no clinical signs or gross necropsy findings suggestive of the cause of death; however, microscopic lesions were consistent with WNV infection, including nonsuppurative encephalitis and myocardial, pancreatic, and splenic necrosis. Necrosis of the thymus and thyroid was also observed in some birds, which has not previously been reported in association with WNV infection. Immunohistochemistry revealed WNV antigen in multiple tissues, including thymus and thyroid, and reverse transcription polymerase chain reaction resulted in the identification of WNV gene sequence in all of the ducklings that were tested. This outbreak is of interest because waterfowl (Anseriformes) are not thought to be particularly susceptible to WNV, and there is little information about WNV infection in prefledging birds. The apparent susceptibility of lesser scaup to WNV demonstrated in this study may have implications for declining lesser scaup populations in the wild.

Malignant mesenchymal tumors in two white-tailed jack rabbits (Lepus townsendii).

Two white-tailed jack rabbits (Lepus townsendii) with proliferative lesions in their internal organs were submitted to the Canadian Cooperative Wildlife Health Centre (Saskatoon, Saskatchewan, Canada) for necropsy because of concern that dogs that had contact with the hares might have been exposed to an infectious disease. In both hares, the primary diagnosis was neoplasia. One hare had metastatic leiomyosarcoma and uterine fibroma, the other had metastatic mesenchymal tumors involving the liver and mesentery. These cases represent the only reports of malignant mesenchymal tumors in white-tailed jack rabbits that we have found in the literature.