HORSES

Alcohol and Gaming Commission of Ontario (AGCO) Equine Incidents in Ontario Racing: 2003 - 2017 postmortem summary

The Alcohol and Gaming Commission of Ontario (AGCO; formerly the Ontario Racing Commission, ORC) continues in its proactive approach to advance racehorse welfare and safety of human and animal participants. In 2003, Ontario became one of the first North American racing jurisdictions to require mandatory reporting of racehorse deaths, in order to monitor, research and improve knowledge of why these events occur. Postmortem (PM) exams conducted at the Animal Health Laboratory through the AGCO Equine Incidents program continue to provide comprehensive data regarding the causes of morbidity and mortality in racehorses in this province. To date, PM has been carried out on 1075 horses through the Equine Incidents program (Table 1). Annual variation in the number of PM cases reflects discretionary requirement for PM on the part of the Registrar of AGCO.

A summary of significant PM findings is provided in Table 2. A comprehensive review of AGCO PM cases was conducted in 2015 as part of a separate retrospective study and as a result, some cases have been reclassified from results presented in previous editions of the AHL Newsletter.  Results of the study were published in the July 2017 edition of the Journal of Veterinary Diagnostic Investigation.

Since 2015, computed tomography (CT) of fractured and contralateral limbs has been carried out on select Equine Incidents postmortem cases through collaboration with the Diagnostic Imaging section of the Ontario Veterinary College Health Sciences Center. The goal of this in-depth examination is to identify pre-existent lesions, primarily in bone, that contribute to catastrophic fractures. The procedure was continued in 2017, with CT imaging of 31 of 34 (91%) limb fracture cases submitted for PM exam. Pre-existent lesions in bone were identified by CT and considered predisposing to fracture in 15 of 31 (48%) cases.

Exercise-associated sudden death is of special concern among those cases reported through the Equine Incidents program (Table 3). In 2017, the cause of death was investigated in 9 horses that died while exercising. Of these, significant pulmonary hemorrhage was evident in 6 horses, and no cause of death was identified in 3 horses. Among all sudden death cases from 2003-2017, significant pulmonary hemorrhage was identified in 84 of 172 (49%) of horses. The cause of death in such cases is often attributed to exercise-induced pulmonary hemorrhage (EIPH), although the pathogenesis of pulmonary hemorrhage in these horses is not well understood. Severe acute hemorrhage involving pericardium or body cavities was identified in 30 of 163 (18%) sudden death cases in previous years, but this finding was not present in any of the sudden death horses examined in 2017. In a significant proportion of exercise-associated sudden death cases from 2003-2017, no significant lesions were identified and the cause of death remained undetermined (40/172, 23%). It has been speculated that exercise-associated cardiac arrhythmia, leading to acute heart failure and pulmonary hypertension, may be the underlying cause of death among many of these horses, and may also contribute to pulmonary hemorrhage in these animals.

Summaries of postmortem submissions to the Animal Health Laboratory under this program and diagnoses by body system for these cases are provided in the tables on page 11.   AHL

References

DeLay J. Postmortem findings in Ontario Racehorses, 2003-2015. J Vet Diagn Invest 2017;29:457-464.

Physick-Sheard PW, McGurrin MKJ. Ventricular arrhythmias during race recovery in Standardbred racehorses and associations with autonomic activity. J Vet Intern Med 2010;24:1158-1166.

Table 1. Breed distribution of AGCO Equine Incidents submissions to the AHL, 2003-2017

Table 2. Significant postmortem lesions identified in AGCO Equine Incidents submissions by body system, 2003-2017.

Table 3. Significant postmortem lesions recorded in exercise-associated sudden death cases, AGCO Equine Incidents, 2003-2017.

AHL accepts EIA electronic submissions via EquusLINK  

Jim Fairles

You can learn more about EquusLINK at: https://www.globalvetlink.com/products/equuslink/

Advantages of this electronic submission process include:

* Faster form completion, including immediate updating of information for correction of omissions.

* Streamlined submission to the lab, including embedded color photographs of horses rather than hand drawings.

* Electronic reporting of results, and streamlined transmission of test results to CFIA.

* All results stored for immediate retrieval and immediate use (no more mailing results).

Traditional EIA submission forms will of course still be accepted.

Note from the CFIA accredited veterinarian's manual: http://www.inspection.gc.ca/animals/terrestrial-animals/diseases/accredited-veterinarian-s-manual/chapter-3/eng/1345233051622/1345233162747?chap=2

“42. The shipment of samples must never be entrusted to the animal owner or exporter. The accredited veterinarian must be able to maintain a chain of custody for samples shipped to the laboratories.”

After-hours drop-offs at AHL-Guelph require authorized signatures to maintain chain of custody.   AHL