Genetics of Osteochondrosis

It is widely agreed that osteochondrosis (OC) is a multifactorial problem with nutrition, environment and genetics all playing a role in its development. This retrospective cross-sectional survey was conducted to evaluate the genetic component of OC and estimate its heritability in a population of Australian Thoroughbreds. The medical records and pre-sale screening radiographs of 1,671 yearlings were reviewed from one veterinary practice. Pedigree information was obtained from the breed registry to estimate heritabilities.

Overall 23% of the horses had at least one OC lesion. OC of the stifle was most common (10%) with the lateral trochlear ridge affected most often. The fetlock and hocks were the next most commonly affected joints, 8% and 6% respectively. Heritability estimates ranged from 0.0 to 0.21 with the distal intermediate ridge of the tibia, dorsoproximal first phalanx, stifle and lateral trochlear ridge of the distal femur having the largest heritability estimates from 0.10 to 0.21. Although the statistical variation was high, after considering the results of this study along with other published work the authors concluded significant modest heritability exists for OC lesions of the stifle, hocks and fetlocks.

They also recognized significant permanent environmental effects attributable to the dam that may reflect farm management practices such as feeding. These results suggest that with more study of the influence genetics and management practices have on the development of OC, selective breeding and careful management could be used to reduce the incidence of this disease in Thoroughbreds.

— Russell J et al.…