Heritabilities of health traits in Swiss Warmblood horses.

This study investigates the inheritability of certain health traits in Swiss Warmblood horses, including sarcoid disease, hoof quality, prognathism, and joint filling potentially related to osteochondrosis. Using clinical examinations and pedigree analysis, researchers found that these traits had varying but generally low heritability, with the exception of sarcoid disease.

Research Goal and Objectives

• The research aimed to provide estimates for the genetic influence or heritabilities of equine sarcoid disease, hoof quality, and potential osteochondrosis indicators in Swiss Warmblood horses.
• This was prompted by a lack of existing knowledge regarding the genetic parameters of health traits in these specific horse breeds.

Methods Used

• Clinical examinations of Swiss Warmblood horses were performed by 13 veterinarians at field tests in Switzerland between 2005 and 2013.
• The tests focused on the presence of sarcoids (a form of skin tumor), hoof horn quality, incisor alignment (prognathism), and increased joint filling, which may refer to osteochondrosis – a joint disorder that often affects horses.
• The findings from these examinations were recorded in a database, which was then used in their analysis. A substantial number of records (3,715) were cross-referenced with a larger pedigree chart of related horses (217,282) to assess genetic trends.
• Variance and heritability of each trait were estimated using an analytical model known as the multiple-trait Gibbs sampler for animal models (MTGSAM).

Research Findings

• All examined traits showed relatively low prevalence rates, ranging from 2.4% to 13.0%.
• Heritability estimates varied across the different health traits. The occurrence of sarcoids showed the highest heritability at 0.21, indicating a moderate level of genetic influence.
• Hooves with significantly brittle and friable horn quality had a heritability of 0.04. Hooves with marked growth ring formation had a heritability of 0.03, and the heritability for prognathism was 0.06—showing low genetic influence.
• The heritability for increased filling of the talocrural joint—an indicator of possible osteochondrosis—was estimated at 0.08, again exhibiting low genetic influence.
• A noteworthy factor impacting the variance of the observations was the influence of the examiner.

Conclusions

• Aside from equine sarcoid disease, the heritability estimates for the other health traits examined were relatively low. This implies that, for these traits, other factors such as environment or care practices could have a significant impact.
• Developing and implementing a standardized examination protocol may help reduce the variance related to individual examiner differences and improve the reliability of the results.