Heritability and prevalence of selected osteochondrosis lesions in yearling Thoroughbred horses

Abstract

SummaryBackgroundOsteochondrosis is considered multifactorial in origin, with factors such as nutrition, conformation, body size, trauma and genetics thought to contribute to its pathogenesis. Few studies have investigated the effects of genetic variability of osteochondrosis in Thoroughbreds.ObjectivesTo describe the prevalence and genetic variability of a subset of osteochondrosis lesions in a group of Thoroughbred yearlings.Study designRetrospective cohort study.MethodsRadiographs of 1962 Thoroughbred yearlings were retrieved from clinical records obtained between 2005 and 2013. Pedigree information was obtained from the Australian Stud Book. Osteochondrosis lesions were documented in selected joints and estimates of heritability were obtained by fitting linear mixed models in ASREML software.ResultsThe overall prevalence of osteochondrosis was 23%. Osteochondrosis was identified in 10% of stifle joints, 6% of hock joints and 8% of fetlock joints. The heritability estimates ranged from 0 to 0.21. The largest estimates were 0.10, 0.14, 0.16 and 0.21 for lesions of the distal intermediate ridge of the tibia, dorso‐proximal proximal phalanx (P1), any stifle osteochondrosis, and lesions of the lateral trochlear ridge of the distal femur, respectively. Although calculated heritability estimates had high standard errors, meta‐analyses combining the present results with published estimates were significant at 0.10, 0.17, 0.15 and 0.20 for stifle, tarsal, fetlock and these joints combined, respectively. In addition, there was a permanent environment attributable to the dam effect.Main limitationsInclusion criteria were based on radiographic findings in specific joints at a specific age range in Thoroughbreds.ConclusionsThe present results indicate that only a proportion of osteochondrosis in Thoroughbreds is heritable. The permanent environment effects of the dam were observed to have effects on some categories of osteochondrosis.

Ultrasonographic screening for subclinical osteochondrosis of the femoral trochlea in foals (28–166 days old): a prospective farm study

“…Furthermore, ultrasonography allows the additional assessment of the depth and width of the lesions in multiple planes, compared with radiography, providing a more accurate Equine Veterinary Journal 50 (2018) 312-320 © 2017 EVJ Ltd assessment. This is particularly important in respect to LRTF osteochondrosis, as heritability is low at this site compared with other joints [26,27]. The current study extends our previous observations to younger foals and reveals that ultrasonography permits assessment of subclinical osteochondrosis lesions.…”

Genetic risk factors for osteochondrosis in various horse breeds

“…Prevalence and heritability estimates vary among breeds, the investigated joints and the predilection sites . Radiographic surveys showed fetlock‐OC prevalences from 7.2 to 14.9% in warmblood breeds and Thoroughbreds , while French trotters (32%) and South German coldbloods (53.9%) showed higher prevalences. Hock‐OC prevalences varied from 5 to 9.7% in warmblood horses and Thoroughbreds , from 17 to 23% in Standardbreds and were 40.1% in South German Coldbloods .…”

Genomics and genetics: A daily double for the horse industry

“…Studies by Russell et al . and Sole et al . , published in this issue demonstrate the genetic components for both health traits and performance.…”