Reproduction

Heritability of SCD Low Among Thoroughbreds, But Still a Risk for Some Stallions

Although the heritability of sudden cardiac death (SCD) among Thoroughbred racehorses is relatively low, certain stallions appear more likely to sire progeny that are at risk, according to a recent study.

Exercise-associated fatalities among Thoroughbred racehorses are frequently caused by SCD. Amie Kapusniak, DVM, and her colleagues, at the University of Adelaide in Australia, wanted to know whether genetics could increase the risk for fatalities, because it was “largely unevaluated in horses,” although it has been postulated.

The researchers reviewed reports of Thoroughbred racing deaths in Australia between 2007 and 2020 to identify horses that suffered SCD. Control horses were selected randomly from races in which SCD occurred, who had not died, or were from races that occurred on the date of the case fatality.

They went back 5 generations of stallions on the pedigree chart for each horse to calculate the risk among progenies.

They identified 93 horses with SCD and 465 control horses. Heritability on the underlying scale was 0.15 ± 0.09 (logit animal) and 0.24 ± 0.12 (normal animal). Inbreeding coefficients were not significantly different between groups. Of the 16 first-generation sires that appeared 5 or more times in the case-control data set, 2 sires more frequently produced affected progeny (OR 7.95–10.41). MeV

For more information:
Kapusniak A, Nath L, Hebart M, et al. Heritability of sudden cardiac death in Thoroughbred racehorses. Equine Vet J. July 10, 2024.
https://beva.onlinelibrary.wiley.com/doi/full/10.1111/evj.14130