he KWPN horses are known around the world for their health and durability. The KWPN’s goal is continuous improvement of its horses through innovative research. Osteochondritis Dissecans (OCD) is a painful disease that affects the joints. Combating OCD is difficult because it is a dynamic process that appears in a horse’s growth phase and is caused by both genetic and environmental factors. A carbohydrate-rich diet and lack of exercise are among the environmental causes of OCD. As part of its commitment to continual improvement, the KWPN is using innovative research to eliminate the genetic causes of the disease.
The KWPN began selecting against OCD in 1987. In 2005 and 2006, the KWPN conducted a population evaluation in which 800 yearlings by 32 different sires were radiographed. The evaluation revealed that the occurrence of OCD in the population was due 25% to genetics and 75% to environmental factors such as nutrition, exercise, and growth rate. Compared with other traits for which the KWPN selects, these statistics indicate that the degree of OCD heritability is sufficient to implement an active selection policy. The population evaluation also revealed a significant difference between stallions with respect to passing on OCD. For example, 58% of offspring by the best stallion scored in the top or “A” category, whereas the same was true for only 9% of offspring by the worst stallion. This considerable difference in offspring underscores the importance of knowing the genetic potential of a stallion. In 2009, the KWPN implemented a new policy for its offspring inspections which requires standard radiographs of newly approved stallions’ first yearlings. The first offspring affected by this policy were those by stallions approved in the spring of 2007 and whose first foals were born in 2008. The goal of the offspring inspection is to assess how a stallion contributes to the occurrence of OCD in a population. These efforts advance the health and well-being of the new generation of horses and, in turn, the future KWPN breeding population.