OAHN Bovine Project: Surveillance of postmortem data from a livestock disposal site

Project Lead: Dr. Cynthia Miltenburg (OMAFRA)

Collaborators:  Dr. Andrew Brooks, Dr. Jim Fairles, Dr. John Hunt, Dr. Steve Crawford

To view the full report, please download the PDF here: https://www.oahn.ca/wp-content/uploads/2021/03/OAHN-BOVINE-PROJECT-SUMMARY-Project-030494-Surveillance-of-postmortem-data-from-a-livestock-disposal-site-For-Web.pdf

Postmortems are a valuable tool for diagnosis and prevention of disease in food animals. Within Ontario, mature cattle are under-represented among cattle postmortem submissions at the provincial diagnostic laboratory. Depending on goals, timing, transport options, and costs, veterinarians might perform postmortems on-farm or submit for postmortem at a diagnostic laboratory. Additionally, within Ontario, mature cattle postmortems are routinely performed by local veterinarians at a centralized livestock disposal unit when requested by producers, other veterinarians, or livestock sales barns. The objectives of the project were to summarize postmortem data available from the veterinarians conducting postmortems at a livestock disposal site as a surveillance activity.

Two veterinarians performing the postmortems at the disposal site agreed to enter the data from postmortems conducted into a central registry for the project for a one-year period. For each postmortem, the veterinarians collected the type of animal (dairy or beef), source (dairy, cow-calf, feedlot, sales barn), county, breed, age, history prompting investigation, and gross postmortem findings/diagnosis if available. A total of 105 bovine postmortems (76 dairy and 29 beef) were conducted between June 2019 and July 2020 by the local veterinary practice. Submissions came from 20 different counties, of which 16% were from salesbarns and 84% direct from farms. A variety of presenting complaints were included in the history but most frequently were sudden death (n=31), down or died in transport (n=18), down on-farm (n=15), and respiratory disease (n=13). By system, for dairy cattle the most frequent findings were cardiovascular (18%), respiratory (16%), and gastrointestinal (11%). No abnormal findings were detected in 21% of cases. A smaller number of beef submissions limited analysis, but the most frequent systems affected were respiratory (24%) and metabolic (10%). Among beef submissions 24% had no abnormal findings and 10% were too extensively autolyzed for a proper postmortem.

These results show that a variety of presentations prompt gross postmortem and a livestock disposal site can be a convenient location to pursue gross PM if it cannot be accomplished on farm. Time to arrival and progressing autolysis within the carcass limited the opportunity to thoroughly investigate the cause of death in some cases.