The longstanding assumption that calves of more than 6 months of age are more resistant to Mycobacterium avium subspecies paratuberculosis (MAP) infection has recently been challenged. In order to elucidate this, a challenge experiment was performed to evaluate age- and dose-dependent susceptibility to MAP infection in dairy calves. Fifty-six calves from MAP-negative dams were randomly allocated to 10 MAP challenge groups (5 animals per group) and a negative control group (6 calves). Calves were inoculated orally on 2 consecutive days at 5 ages: 2 weeks and 3, 6, 9 or 12 months. Within each age group 5 calves received either a high – or low – dose of 5 × 109 CFU or 5 × 107 CFU, respectively. All calves were euthanized at 17 months of age. Macroscopic and histological lesions were assessed and bacterial culture was done on numerous tissue samples. Within all 5 age groups, calves were successfully infected with either dose of MAP. Calves inoculated at < 6 months usually had more culture-positive tissue locations and higher histological lesion scores. Furthermore, those infected with a high dose had more severe scores for histologic and macroscopic lesions as well as more culture-positive tissue locations compared to calves infected with a low dose. In conclusion, calves to 1 year of age were susceptible to MAP infection and a high infection dose produced more severe lesions than a low dose.

This study describes the development, implementation, and psychometric assessment of the multiple mini-interview (MMI) for the inaugural class of veterinary medicine applicants at the University of Calgary Faculty of Veterinary Medicine (UCVM). The MMI is a series of approximately five to 12 10-minute interviews that consist of situational events. Applicants are given a scenario and asked to work through an issue or behavioral-type questions that are meant to assess one attribute (e.g., empathy) at a time. This structure allows for multiple assessments of the applicants by trained interviewers on the same questions. MMI scenario development was based on a review of the noncognitive attributes currently assessed by the 31 veterinary schools across Canada and the United States and the goals and objectives of UCVM. The noncognitive attributes of applicants (N=110) were assessed at five stations, by two interviewers within each station, on three items using a standardized rating form on an anchored 1-5 scale. The method was determined to be reliable (G-coefficient=0.88) and demonstrated evidence of validity. The MMI score did not correlate with grade-point average (r=0.12, p=0.22). While neither the applicants nor interviewers had participated in an MMI format before, both groups reported the process to be acceptable in a post-interview questionnaire. This analysis provides preliminary evidence of the reliability, validity, and acceptability of the MMI in assessing the noncognitive attributes of applicants for veterinary medical school admissions.

BackgroundExamination of bile could be useful to diagnose Platynosomum spp.‐induced cholangitis in cats. Obtaining bile via percutaneous ultrasound‐guided cholecystocentesis (PUC) is possible but raises safety concerns in cats with severe cholecystitis.ObjectivesThe objectives of this study were to investigate the use of PUC to collect bile samples from cats with known platynosomosis and to determine if bile analysis could be a diagnostic test.AnimalsTwenty‐seven free‐roaming cats positive for Platynosomum spp. eggs via fecal examination.MethodsIn this prospective study, fecal egg counts were performed by double centrifugation with Sheather's solution. Bile was collected using PUC from anesthetized cats. Egg counts in bile were performed with a stereoscope. Euthanasia and postmortem examination were performed immediately after PUC.ResultsAll cats had ultrasound (US) evidence of cholangitis or cholecystitis. Thirty‐nine PUCs were performed with 14 cats having 2 PUCs 12 or 24 days apart. Postmortem examinations showed no overt gallbladder damage or leakage but fresh blood was noted in the gallbladder lumen of 3 cats. Median Platynosomum spp. egg counts were higher in bile (1450 eggs/mL; IQR, 400; 5138 eggs/mL) as compared to feces (46 eggs/mL; IQR, 10; 107 eggs/mL) (P < .001).Conclusion and Clinical ImportanceBile egg count analysis is an alternative method with higher egg counts as compared to fecal egg count analysis for the diagnosis of platynosomosis. Obtaining bile via US guidance is technically feasible and safe in cats with cholangitis/cholecystitis. Cholecystocentesis and bile analysis are especially relevant for those cats with chronic cholangitis/cholecystitis and negative fecal egg counts for Platynosomum.

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Edwardsiella ictaluri, a Gram-negative enteric bacterium, is the known etiological agent of enteric septicemia of catfish. In the last few years, different strains have been implicated as the causative agent of mortality events in cultured fish, including Nile tilapia Oreochromis niloticus L. Due to the emergent nature of edwardsiellosis in non-ictalurid fish, little is known about the dynamics of E. ictaluri infection in tilapia. The purpose of this study was to gain a better understanding of the pathogenesis of edwardsiellosis in tilapia by determining the median lethal and infective doses, tissue targets of infection, rate of bacterial dissemination, and the specific tissue response to E. ictaluri following an immersion challenge with bacterial strains recovered from outbreak events in tilapia. In addition to histopathology assessment, the bacterial burdens in several tissues of infected fish were determined over a 2 wk course of infection using quantitative real-time PCR (qPCR). The collected data suggest the cutaneous and oral routes as the main ports of entry for the organism, which later spreads hematogenously throughout the body. Even though histopathological assessment of infected fish revealed involvement of a wide range of tissues, the severity of the necrotizing and granulomatous lesions in the spleen and head kidney, with concomitant high levels of bacterial DNA in these organs determined by qPCR, identifies them as the main targets of infection. KEY WORDS: Edwardsiella ictaluri · Histopathology · Pathogenesis · Real-time PCR · Tilapia Resale or republication not permitted without written consent of the publisherDis Aquat Org 104: [105][106][107][108][109][110][111][112] 2013 Hanson 2011). In Edwardsiella ictaluri-infected tilapia, the most consistently reported findings are multifocal nodulations in the spleen, head kidney, and hepato megaly with a reduced fat reserve in the liver and peritoneal cavity. Moreover, microscopically, a severe chronic inflammatory infiltrate is observed in the spleen, head kidney, and liver, with multifocal areas of necrosis and granuloma formation (Soto et al. 2012).The use of experimental animal models remains critical to elucidating disease pathogenesis, especially when studying emergent diseases. In the present study, we used quantitative real-time PCR (qPCR) and histological analysis to evaluate the dissemination of Edwardsiella ictaluri in Nile tilapia under controlled conditions. MATERIALS AND METHODS BacteriaEdwardsiella ictaluri strain RUSVM-CO-2-5 was originally a clinical isolate obtained from a recently reported outbreak of edwardsiellosis in cultured tilapia (Soto et al. 2012). The bacterium was grown on tryptic soy agar (TSA) supplemented with 5% sheep blood at 28°C for 48 h. Three colonies were suspended in 100 ml of brain-heart infusion broth (Remel-Thermo Fisher Scientific), and grown overnight at 150 rpm in a shaking incubator maintained at 27°C. The next morning, bacteria were pelleted, washed twice in 1× phosphate-buffered saline (PBS), ...