Chronic wasting disease in Canada: Part 1

The purpose of part 1 is to provide an overview of published literature (1980-2002) on chronic wasting disease (CWD) to inform Canadian readers about the disease and to explain Canadian regulatory approaches to the surveillance and control of CWD. Much of the scientific information is drawn from American publications obtained from internet searches in PubMed and Medline databases. The following keywords were used: chronic wasting disease, prion, diagnosis, transmissible spongiform encephalopathies, CWD and deer, CWD and elk, and CWD and environment. The article also presents information from Canadian publications and unpublished observations, Canadian Food Inspection Agency (CFIA) documents, and both government and nongovernment internet Web sites. The article highlights some different features of CWD in Canada, as compared with the situation in the United States, and mentions public health implications of the disease. It also describes the basis for development of Canada's surveillance and control program. Part 2 will detail the activities and results of the surveillance and control program during 2000 to 2002 and discuss factors that will influence the feasibility of eradicating CWD. Chronic wasting disease appears to have been introduced into Canada through the importation of infected farmed elk from the United States in the late 1980s and early 1990s, at a time when little was known about the disease. Since then, eradication efforts in Canada have led to the control of the spread of CWD in the farmed elk industry. Still, management of this disease, especially in free-ranging cervids, is a challenge.     

Efficacy of pre-treatment with lufenuron for the prevention of Microsporum canis infection in a feline direct topical challenge model

Oral lufenuron is reportedly an effective treatment for some cats with dermatophytosis. The purpose of this study was to determine if lufenuron, when used as a pre-treatment prior to challenge exposure, would be protective against the development of infection after the direct topical application of fungal macrocondia (Microsporum canis spores). Three groups (n = 6/group) of juvenile cats were treated with either monthly oral lufenuron (30 or 133 mg/kg) or placebo. After 2 months of treatment, kittens were challenged using 10(5)Microsporum canis spores applied to the skin under occlusion. Cats were examined weekly and the following data collected: Wood's lamp examination; scoring for scale/crust, erythema and induration; lesion size; and the development of satellite lesions. Fungal cultures were performed bi-weekly. All cats became infected; the infections progressed, and then regressed, in a similar fashion in all groups. There were no consistent statistically significant differences in weekly infection scores between treated and untreated cats throughout the study. Treated cats did not recover faster than untreated cats. We conclude that oral lufenuron at the dosing schedule and conditions used in this study did not prevent dermatophytosis or alter the course of infection by direct topical challenge.     

The clinical usefulness of the ventrodorsal versus dorsoventral thoracic radiograph in dogs

Differences exist in the ventrodorsal (VD) and dorsoventral (DV) radiographic views of the canine thorax. One view may be preferred over another because of how it portrays different areas of interest or different disease conditions. The VD view is indicated for evaluation of the cranial and caudal mediastinum, the caudal vena cava, and the accessory lung lobe, and in cases of pleural effusion. Indications for the DV view include assessment of a consistent cardiac silhouette, evaluation of the pulmonary lobar vessels, and evaluation of the structures of the dorsal thorax, such as hilar lymph nodes, the caudal dorsal lungs, trachea, mainstem bronchi, and left atrium.     

The first reported case of rabbit hemorrhagic disease in Canada

In March 2011, rabbit hemorrhagic disease (RHD) was suspected in a 1-year-old male neutered lop-eared rabbit that had acute onset liver failure. Gross pathology, histopathology, immunohistochemistry, partial nucleic acid sequencing and phylogenetic analysis of the major capsid protein (VP60) and animal inoculation studies all supported this diagnosis making it the first confirmed case of RHD in Canada.     

Historical Forage Productivity and Cost of Capital for Cow-Calf Production in California

Exposure of livestock grazing to forage productivity variation and to market fluctuations affects the risk of investment and returns from cow-calf operations, but little work has been done to empirically compare these returns to the returns that would be demanded by financial markets from assets with similar risk and return characteristics. This study uses historical forage production data from three rangeland locations in California, and cattle and hay prices, to simulate financial statements for three hypothetical cow-calf producers in the period 1988–2007. Return on investment from year to year incorporates the variability and risk associated with dependence on natural forage production. Performance is then compared to the actual performance of a diversified portfolio of assets using the Capital Asset Pricing Model, from which the theoretical cost of capital for these hypothetical grazing enterprises is derived. Much like other agricultural enterprises, cow-calf production in California has low market risk and a low theoretical cost of capital. This theoretical cost of capital is still greater than the historical return from livestock production (excluding land appreciation) in the western United States, adding further backing to the point often made in the literature that ranchers who engage in cow-calf production are receiving benefits beyond the commercial returns from livestock production alone.