Diagnostic tests are invaluable to the practice of veterinary medicine. Using them correctly and interpreting the results appropriately depend on having a good understanding of the basic principles outlined in this article. Topics covered include sensitivity and specificity, agreement among tests, u...

Recent international developments in the area of infectious disease control and nontariff trade barriers, along with possible zoonotic concerns, have provoked a revival of interest in Johne's disease in Canada and elsewhere. The bacterium causing Johne's disease, Mycobacterium avium subspecies parat...

Part I of this 2-part review examined the clinical stages, pathophysiology, diagnosis, and epidemiology of Johne's disease, providing information relevant to Canada, where available. In Part II, a critical review of the economic impacts of the disease, risk factors, and important control measures ar...

Enzyme-linked immunosorbent assays (ELISAs) are used in Johne's disease (JD) control programs as a first screening for presence of the disease in a herd. A high sensitivity of the ELISA is therefore important, yet the commonly used ELISAs have relatively low sensitivity. The inclusion of an abs...

The primary objective was to compare microbiological results of the University of Minnesota Tri-plate and the 3M Petrifilm Staph Express (STX) Count Plate to standard culture techniques for identification of clinical mastitis caused by Staphylococcus aureus. The secondary objective was to evaluate t...

The objective was to determine test characteristics and compare 2 potential on-farm culture systems for clinical mastitis, the Minnesota Easy Culture System II Bi-plate and Petrifilm. The tests were evaluated using clinically positive mastitic milk samples (n=282) to determine their ability to diffe...

The prevalence of Mycobacterium avium ssp. paratuberculosis (Mptb) in culled dairy cattle in Eastern Canada and Maine was determined to be 16.1% (95% confidence interval 13.8 to 18.3%) based on a systematic random sample of abattoir cattle. Mesenteric lymph nodes and ileum from 984 cows were examine...

Paired samples of formalin-fixed, paraffin-embedded ileum and lymph node from 204 culled dairy cows were investigated for evidence of infection by Mycobacterium avium subsp. paratuberculosis. Of the samples, 151 were from animals that were tissue-culture positive for M. avium subsp. paratuberculosis...