United States Eventing Association

Sudden deaths in horses remain one of the most complex and least understood challenges in equine medicine. Often occurring without warning in otherwise healthy animals, these rare but devastating events can take place during or immediately after exercise—leaving veterinarians, trainers, and owners searching for answers.

Grayson-Jockey Club Research Foundation is at the forefront of efforts to better understand, detect, and ultimately prevent these incidents through strategic investment in cutting-edge veterinary research.

"In eventing, we ask our horses to be brave, powerful, and endlessly giving—especially across cross-country, where the physical demands are greatest," said Jamie Haydon, president of Grayson. "When even the healthiest horse can carry hidden cardiac risk, research becomes our most important safeguard. It gives riders the knowledge to make better decisions through early detection, the confidence to compete responsibly, and the ability to protect the partner who gives them everything.”

Cardiac-related conditions are believed to account for approximately half of exercise-associated sudden deaths. However, many horses exhibit underlying heart rhythm irregularities that are not outwardly detectable, and even with post-mortem evaluation, a significant number of cases remain unexplained.

“Despite advances in veterinary medicine, critical unknowns persist,” said Haydon. “Our goal is to move the industry from reacting to these events to preventing them altogether.”

Driving research that delivers answers, Grayson-funded research is making measurable progress by:

• Advancing cardiac monitoring tools to enable earlier detection of risk
• Supporting large-scale studies to identify patterns and underlying causes
• Fostering collaboration among veterinarians, researchers, and industry leaders
• Shifting the field toward proactive, data-driven prevention

Recent studies supported by the foundation are delivering meaningful insights into equine cardiac health.

Innovative treatment development through research: Dr. Annelies Decloedt at Ghent University is evaluating Ketodoxapram, a novel pharmacological approach to treating atrial fibrillation. The therapy targets specific cardiac channels with the goal of providing a safer and more effective alternative to current treatment options.

Predictive screening advancements: At the University of Minnesota, Dr. Molly McCue and Dr. Sian Durward-Akhurst are pioneering methods to predict exercise-associated arrhythmias using resting electrocardiograms (ECGs). Early findings suggest that as little as one minute of resting ECG data may help identify horses at increased risk—offering a practical and scalable screening tool.

Large-scale data is driving industry insight: Through one of the most comprehensive studies of its kind, researchers have collected more than 5,400 ECGs from over 1,100 Thoroughbred racehorses. Early analysis reveals that while arrhythmias are extremely common—even among healthy horses—distinguishing benign irregularities from those that pose serious risk remains a critical challenge. This study aims to improve interpretation of ECG findings, develop predictive tools based on heart rate variability, and provide veterinarians and regulators with clearer guidance on when intervention is necessary.

All of this research will have a great impact, and the effects will extend across the broader equine industry—supporting veterinarians in their diagnoses, helping trainers make informed decisions, aiding regulators in protecting horse welfare, and ultimately safeguarding our equine and human athletes.

Each advancement helps answer the questions posed by sudden deaths, but with traditional funding sources for equine research declining, continued philanthropic support remains essential to sustaining this progress. “Every breakthrough begins with investment in science,” said Haydon. “Through continued support, we can turn unanswered questions into life-saving solutions.”

To learn more about the Grayson-Jockey Club Research Foundation visit, grayson-jockeyclub.org.