Not only might you get a horse that cannot run far at all, but unsoundness also becomes an issue. Other defects include overly long and sloping pasterns, which predispose the horse to chips in the fetlocks and can lead to sesamoid problems and problems with the flexor tendons. But it's dangerous to breed for just one thing. Metabolism And Mind-Set Both Quarter Horses and Thoroughbred racehorses, says Loving, also need bodies that run efficiently during anaerobic exercise. Some aspects of metabolic efficiency are heritable, making it easier for some horses to condition and compete to their fullest genetic potential.
Endurance horses demonstrate metabolic efficiency by rapid heart rate recoveries.
On the other hand, some horses which are less well-endowed genetically can be trained to develop excellent metabolic capabilities through strategic conditioning practices and consistent training for the intended exertion. Unlike equine track stars, endurance horses also must be able to make a rapid metabolic recovery after exertion, says Loving. Many horses win simply by having a faster recovery rate at vet checks. They arrive and almost immediately meet the pulse criteria, get shuttled through the exam, and end up passing other horses whose progress has been delayed because they've taken longer to reach the pulse criteria. This is heritable in that tem-perament and disposition are often heritable.