Sudden death in sport and riding horses during and immediately after exercise: A case series.

Sudden death occurred in many types of equestrian sports and in riding horses. Death outside competition was more common suggesting that registries based on reports from official veterinarians underestimate the magnitude of this problem. Rider injuries were not uncommon when ridden horses collapsed and died. A definitive diagnosis for the cause of death was not commonly achieved and cardiovascular origin was the most common where a diagnosis was proposed by survey respondents.