An observational study of mortality on bison farms in Saskatchewan with special emphasis on malignant catarrhal fever

In December 2011, the Malignant Catarrhal Fever (MCF) Task Force in Saskatchewan recommended that research be conducted on the relationship between the proximity of bison and sheep under typical commercial production settings and bison deaths due to MCF. The objective of this study was to evaluate all causes of death in bison herds and compare the incidence of MCF in herds at varying distances of exposure from sheep operations. Necropsies were completed on 76 of 133 bison reported to have died during the 18-month study period. A total of 7 MCF deaths was reported from 2 large herds within 1.0 km of sheep operations. Although there was a greater risk of MCF deaths in bison herds within 1.0 km of sheep operations than in herds more than 1.0 km away, the overall incidence of MCF deaths within the study period was very low. Most deaths were attributed to non-infectious causes, including copper deficiency.     

Defining important canine zoonotic pathogens within the Prairie Provinces of Canada

The goal of this study was to establish a short list of zoonotic pathogens involving the domestic dog that can be prioritized for a companion animal surveillance program specific to the Prairie Provinces of Canada. A list of pathogens documented in dogs was created through a comprehensive review of infectious disease textbooks for the following taxonomical categories: bacteria, ectoparasites, fungi, helminths, protozoa, rickettsia, and viruses. This created an initial list of 594 pathogens that was then pared down through an extensive review of the literature using the following criteria: i) the pathogen is zoonotic/sapronotic/anthroponotic; ii) the dog is involved in transmission to humans, maintenance, or detection of the pathogen; and iii) there is a level of risk for occurrence of the pathogen in Canada. This process yielded a final list of 84 pathogens and 3 supplementary lists of canine zoonotic/sapronotic/anthroponotic pathogens that may become relevant to future surveillance programs.     

Distribution of Toxocara infection in the environment and in definitive and paratenic hosts in Estonia

The aim of the study was to elucidate the distribution and possible transmission routes of Toxocara spp. infection in Estonia. Out of 454 faecal and sand samples collected from park lawns and sandpits in the town of Tartu, 19 were Toxocara positive (4.2%). Out of the 45 sandpit samples 17.8% were Toxocara positive. Cat faeces was found in 21 sandpit samples. Parasitological necropsies were performed on 41 euthanised stray dogs and 27 cats in the Tallinn Dog Home. Additionally, 13 wild free-roaming brown rats (Rattus norvegicus) were captured from the Tallinn Dog Home territory, necropsied and studied for the presence of Toxocara larvae. Toxocara canis adults were found in 14.6% of the dogs and Toxocara cati (syn. mystax) adults in the small intestines of 48.2% of the cats examined. Larval infection was detected in the kidney and liver in 5 dogs (12.2%). Our study demonstrated only low-level larval Toxocara infections in adult dogs. Toxocara larvae were not found in cats and brown rats. According to the results of this study, cats more often carry Toxocara infection than dogs. Under our conditions, stray and free-roaming cats are the main contaminators of the environment with Toxocara eggs. Children playing in sandpits are the main risk group for larval toxocarosis.     

Effects of a standardized anesthetic protocol on hematologic variables in healthy cats

This study evaluated the effects of an anesthetic protocol using intravenous ketamine and midazolam, and intramuscular buprenorphine on hematologic variables in cats. Twelve healthy adult cats had blood collected for a complete blood count before and after the induction of anesthesia. There were significant decreases in red blood cell counts, hemoglobin concentrations and hematocrits after the induction of anesthesia. On average, red blood cell counts and hematocrits decreased by 25%, and hemoglobin concentrations decreased by 24%. Based on hematocrit, 3/12 samples (25%) taken while the cats were anesthetized would have been interpreted as belonging to anemic patients while none of the cats would have been considered anemic before anesthesia. This study suggests that a complete blood count performed on blood taken under anesthesia with this anesthetic protocol should be interpreted cautiously in order to not make a false diagnosis of anemia.     

Effects of oral selenium supplementation on mastitis markers and pathogens in Estonian cows

The effects of selenium supplementation on mastitis parameters in milk and on glutathione peroxidase (GPx) levels in blood were evaluated. Fifty-five Estonian dairy cows were allocated to selenium-supplemented (n=39) and nonsupplemented (n=16) groups. The supplemented group received 0.2 ppm organic selenium in the form of selenium yeast in their diet daily for 8 weeks. The nonsupplemented cows received their standard diet with no selenium supplementation. Mastitis parameters (i.e., bacteriologic findings and somatic cell count, N-acetyl-beta-D-glucosaminidase, and bovine serum albumin concentration) and GPx levels were monitored. The increase in the activity of GPx was significantly (P<.001) greater in selenium-supplemented cows than in nonsupplemented ones. Milk samples from each quarter were examined before and 8 weeks after initiation of the study. The proportion of quarters still pathogen-free after 8 weeks was significantly (P<.01; odds ratio [OR]=9.7) higher in selenium-supplemented cows than in nonsupplemented cows. However, when quarters milk-tested as pathogen-infected at the start of the study were reexamined after 8 weeks, there was no significant (P=.14; OR 3.6) difference in the proportion of pathogen-free quarters between selenium-supplemented cows and nonsupplemented cows. Differential positive rate (Youden's index) revealed that individual quarters were more prone to be infected by pathogens when the blood GPx activities in cows were below the cutoff value of 3.3 microkat/g hemoglobin than when GPx activity was above this value. It was concluded that selenium supplementation in cows with low GPx activity seems to support udder defense mechanisms that favor reduction of the incidence of new mastitis cases.     

The prevalence and risk factors of oesophageal and nonglandular gastric lesions in Thoroughbred racehorses in Saskatchewan

The objective of this study was to investigate the prevalence, severity and risk factors associated with oesophageal and nonglandular gastric lesions in Thoroughbred racehorses in active training in Saskatoon. Mature Thoroughbred horses (n = 94), stabled at Marquis Downs racetrack in Saskatoon, Saskatchewan, Canada, and trained by different trainers (n = 14) for a minimum of one month were included in the study. Horses were examined by gastroscopy and a lesion grade was assigned for each individual horse. Of the 94 horses, 79 (84%) had nonglandular gastric lesions, 70 (74.5%) had gastric ulcers, giving a prevalence of 74.5%, and 9 out of 94 horses (9.6%) had hyperkeratosis and/or hyperaemia. None of the horses had oesophageal lesions. Gender, age, number of races raced, place obtained in those races, history of lameness, history of medical conditions, and history of medications in a 2 month period prior to the gastroscopic examination were not statistically significant as potential risk factors for the prevalence and severity of nonglandular gastric lesions.     

Carbon and nitrogen dynamics in zero-water exchange shrimp culture as indicated by stable isotope tracers

The uptake and assimilation of nitrogen and carbon by shrimp were measured in 1200 L mesocosms using stable isotope enrichments. Labels were added via ¹⁵N‐, ¹³C‐glycine and amino acid mixtures in feeds or as ¹⁵NH₄⁺ to pond water. Label was incorporated into shrimp via algal growth indicating that up to 31% of nitrogen requirements were derived from pond ecosystem dynamics. This value is low in comparison with other shrimp aquaculture isotopic tracer studies but is probably due to differences in shrimp‐rearing conditions. Direct incorporation of the enriched feed label was low in shrimp muscle tissue (3.3% for ¹³C‐glycine, 5.9% for ¹⁵N‐glycine and 7.8% for ¹⁵N‐amino acid mixture). Mass balance calculations indicate the remaining shrimp biomass was derived from feed, but loss of label into solution during feeding led to underestimation based on tracers. Incorporation of isotopic labels into feed as large molecular weight proteinaceous or microencapsulated/fat‐coated compounds is recommended to prevent dissolution and loss.     

Step ostectomy as a treatment for varus deformity of a metatarsophalangeal joint in a 4.5-month-old colt

A 4.5-month-old quarter horse colt was presented with severe right hind metatarsophalangeal varus, present since birth. On radiographs, it was determined that there was a 16 degree deviation with the pivot point at the distal physis of the 3rd metatarsal bone. A step ostectomy in the sagittal plane corrected the deformity.     

A case-control study of factors associated with development of clinical disease due to West Nile virus, Saskatchewan 2003

REASON FOR PERFORMING STUDY: West Nile virus (WNV) was first diagnosed in Saskatchewan equids in 2002. AWNV epidemic was considered highly likely for 2003, which would provide a unique opportunity to study all aspects of WNV subclinical infection and clinical disease development in a relatively naive population. HYPOTHESIS: There are individual equid attributes and management risk factors associated with development of clinical disease. Specifically, this study could address the question of vaccine efficacy for the prevention of development of clinical disease. METHODS: A case-control study was conducted in the summer of 2003 during a province-wide outbreak of WNV. Between 5 and 10 equids were sampled from each of 23 case premises with clinical disease and 23 control premises with no apparent or confirmed clinical disease. Data were analysed to identify risk factors for the development of clinical disease. RESULTS: The proportion of equids serologically positive for natural exposure to West Nile virus was 64% (193/300). Nonvaccinated equids were 23 times (95%CI limits 3.0, 168.5, P = 0.002) more likely to develop clinical disease than those vaccinated. The estimate of vaccine efficacy in this field study was 96% (95%CI limits 67%, 99%). CONCLUSIONS: The study demonstrated that vaccination was strongly associated with the prevention of clinical disease. POTENTIAL RELEVANCE: Vaccination is an effective, practical method of prevention of clinical disease.