Genetics Behind Horse Height Helps Breeding Programs

Horse owners often try to predict the adult height of young horses. According to Welsh researchers*, knowing which genes play a role in regulating body size, including height, could provide important information regarding growth and development mechanisms, and contribute to mare and stallion selection in breeding programs.

“A horse’s size influences both performance and maintenance decisions,” noted Laura Petroski-Rose, B.V.M.S, a Kentucky Equine Research veterinarian.

For example, taller horses typically have a longer stride and slower stride frequencies, both of which contribute to increased speed—a characteristic beneficial to a multitude of sport horses. For dressage horses, height at the withers relates to important kinematic variables.

She added, “Maintenance costs also increase with size, with larger animals requiring larger paddocks, stalls, and amounts of feeds, supplements, and medications.”

Despite decades of research in human medicine, no single gene appears to control height. Instead, it appears that adult height results from the interaction of many genes and environmental factors, called epigenetic traits, which individually would have a small impact on overall height.

Petroski-Rose contrasted the height situation in humans to horses where horse height has been heavily selected for.

“Genes specific to adult height could play a more profound role in horses than what research has found in humans,” she explained.

The Welsh research team, however, found that DNA collected from 105 ponies and cobs identified “…222 highly significant height-associated” genetic regions spread over multiple equine chromosomes.

Does this finding suggest that genetic control over horse height is a pie in the sky idea? The researchers believe this data can be combined with that obtained from other horse breeds to identify both between and within breed genetic data regarding height prediction. Further, this study contributes to the overall knowledge of height-related traits.

“Regardless of how small or large your companion will ultimately be, a slow and steady growth rate in their early years will help ensure a healthy musculoskeletal system. Kentucky Equine Research offers nutritional consultation for feeding recommendations throughout a foal’s formative years. We also offer joint and bone supplements to support that bones and tissues that support your horse for the duration of their lives,” advised Petroski-Rose.

Examples of such products include DuraPlex, a mineral and vitamin supplement designed to positively support bone quality, and Triacton, to help increase bone density and strength.

*Skujina, I., C.L. Winton, M.J. Hegarty, et al. 2018. Detecting genetic regions associated with height in the native ponies of the British Isles by using high density SNP genotyping. Genome. 61(10):767-770.