Management factors associated with farrowing rate in commercial sow herds in Ontario

The objectives of this study were to determine associations between low farrowing rate and various management factors in sow herds. In 30 sow herds, a management survey, breeding observations, semen evaluation, and semen storage temperature monitoring were completed. Herds with an average farrowing rate of < 85% were classified as low farrowing rate herds while those with an average farrowing rate of ≥ 85% were classified as good farrowing rate herds. Low farrowing rate herds were more likely than good farrowing rate herds to move boars into gilt pens for estrus detection, breed a high proportion of sows by artificial insemination (AI) only, start heat detection 3 d post-weaning, wipe the vulva prior to breeding, and use “hands-free” AI devices.     

Disseminated candidiasis secondary to fungal and bacterial peritonitis in a young dog

Objective – To describe a severe case of bacterial sepsis and disseminated candidiasis in a previously healthy dog.
Case Summary – Fungal sepsis was identified in a 2-year-old dog following intestinal dehiscence 4 days after abdominal surgery. Septic peritonitis was identified at admission and evidence of dehiscence at the previous enterotomy site was found during an exploratory laparotomy. Both gram-positive cocci and Candida albicans were cultured from the abdominal cavity. Candida sp. was also subsequently cultured from a central venous catheter. Euthanasia was performed due to failure to respond to therapy. Fungal organisms, morphologically consistent with Candida spp., were found in the lungs and kidney on postmortem histopathologic examination indicating disseminated candidiasis.
New or Unique Information Provided – Candida peritonitis is a well-recognized entity in humans and contributes to morbidity and mortality in critically ill patients. Abdominal surgery, intestinal perforation, presence of central venous catheters, and administration of broad-spectrum antibiotics are all considered to be suspected risk factors. This report describes the first known case of systemic candidiasis occurring secondary to Candida peritonitis and bacterial sepsis in a critically ill dog.     

Histological and morphometric lesions in the pre-clinical,developmental phase of insulin-induced laminitis in Standardbred horses

Lamellar pathology in experimentally-induced equine laminitis associated with euglycaemic hyperinsulinaemia is substantial by the acute, clinical phase (～48 h post-induction). However, lamellar pathology of the developmental, pre-clinical phase requires evaluation. The aim of this study was to analyse lamellar lesions both qualitatively and quantitatively, 6, 12 and 24 h after the commencement of hyperinsulinaemia. Histological and histomorphometrical analyses of lamellar pathology at each time-point included assessment of lamellar length and width, epidermal cell proliferation and death, basement membrane (BM) pathology and leucocyte infiltration. Archived lamellar tissue from control horses and those with acute, insulin-induced laminitis (48 h) was also assessed for cellular proliferative activity by counting the number of cells showing positive nuclear immuno labelling for TPX2.Decreased secondary epidermal lamellar (SEL) width and increased histomorphological evidence of SEL epidermal basal (and supra-basal) cell death occurred early in disease progression (6 h). Increased cellular proliferation in SELs, infiltration of the dermis with small numbers of leucocytes and BM damage occurred later (24 and 48 h). Some lesions, such as narrowing of the SELs, were progressive over this time period (6–48 h). Cellular pathology preceded leucocyte infiltration and BM pathology, indicating that the latter changes may be secondary or downstream events in hyperinsulinaemic laminitis.     

Presentation of postweaning Escherichia coli diarrhea in southern Ontario, prevalence of hemolytic E. coli serogroups involved, and their antimicrobial resistance patterns

Post-weaning Escherichia coli diarrhea (PWECD) in Ontario was investigated using a case-control study involving 50 Ontario nurseries. The clinical signs and the impact on productive parameters were determined by means of a producer survey. The hemolytic E. coli serogroups involved in PWECD (O149:K91:K88) were examined in this study. Based on a polymerase chain reaction test, the hemolytic E. coli from 82% of the case herds were positive for 3 enterotoxins (STa, STb, and LT), those from 12% of the case herds were positive for STb and LT only, and those from one herd (6%) were positive for 3 enterotoxins, as well as for verotoxin and F18 pili. The E. coli involved in disease were resistant to multiple antibiotics. Case farms commonly used a wide variety of antibiotics either in the feed or water, or as injectable drugs. The most common antibiotic used to treat PWECD on the study farms was apramycin, but evidence of resistance to this antibiotic was noted. The PWECD problem was commonly seen within a week of weaning but onset of diarrhea was reported as late as the grower-finisher stage. Growth rate was poorer in case herds and mortality was higher than in control herds, demonstrating that PWECD is an economically important disease in Ontario.     

The use of epidemiology to enhance production animal research

The approach to understanding the impact of management and disease in production animal systems has evolved with the advent of both routine on-farm data collection and new analytic epidemiology techniques. Epidemiology provides a tool to describe the host-agent-environment triad and the impact of multiple variables on productivity and health recognized by production animal veterinarians in their day-to-day work. Field trials enable veterinarians to systematically test whether or not a new treatment improves the health of the animal populations in their geographic region and under their production systems. Hypothesis-specific coding techniques, such as hierarchical variables, are used in a systematic manner to understand well-defined biological phenomenon. Clustering at multiple levels has provided the challenges of measuring management changes in each level. Using random effects models allow us to determine the relative importance of each level on the dependent variable. As epidemiologists, we have taken advantage of analytic techniques used in other fields of science. Geo-spatial statistics has been used to understand the clustering and spread of diseases and more recently, to interpret the laboratory findings related to the introduction of an exotic strain of the influenza virus. Dr. Martin, through his work as a veterinary epidemiologist and that of people he has influenced, has been an international leader in promoting the optimal health and productivity of animal populations and of ensuring the safety of foods of animal origin and preventing animal-related disease in humans.     

Efficacy of fipronil, amitraz and (S)-methoprene combination spot-on for dogs against adult dog fleas (Ctenocephalides canis, Curtis, 1826)

A novel spot-on formulation combining fipronil, amitraz and (S)-methoprene (CERTIFECT?, Merial Limited, GA, USA) was evaluated in adult Beagle dogs in a study to determine its adulticidal efficacy against the dog flea (Ctenocephalides canis, Curtis, 1826). Sixteen dogs were randomly allocated to treatment groups: 8 dogs served as untreated controls, and 8 dogs were treated once. Treatment consisted of applying a new combination formulation to deliver at least 6.7mg fipronil/kg body weight (bw), 8.0mg amitraz/kg bw, and 6.0mg (S)-methoprene/kg bw. The combination was designed to enhance the efficacy against ticks of the original fipronil/(S)-methoprene combination. Each dog was infested with 100 adult unfed dog fleas within 24h prior to treatment and then at weekly intervals for 8 weeks after treatment. At 24h after treatment or after each subsequent infestation, each dog was combed thoroughly to remove live fleas to be counted. A single treatment with CERTIFECT provided excellent knock-down of fleas within 24h after treatment and controlled re-infestations for up to 7 weeks (efficacy ≥96.5%, p<0.05).