A study shows that one problem associated with prematurity in foals can have a lifelong impact on athletic performance.

Researchers at Rood and Riddle Equine Hospital in Lexington, Kentucky, and Ohio State University in Columbus reviewed the records of newborn Thoroughbred foals treated at Rood and Riddle from 1994 to 2011.

In particular, the researchers examined radiographs of each foal’s hocks for signs of incomplete ossification of the cuboidal bones, which make up the tarsus and carpus. Ossification—the conversion of cartilage to bone—typically concludes during the final weeks of gestation. If the process is not completed before birth, the still-soft bones can be crushed when the foal stands, leading to deformation and soundness problems.

The researchers graded the observed ossification on a four-point scale, with “1” being the least complete and “4” the most complete. Comparing these scores to the length of each foal’s gestation, they found that those with grade 1 and 2 ossification were usually born after a shorter gestation—325 days or less. Equine gestation averages from 320 to 362 days.

Click here to read about reasons for foal loss.

The researchers also reviewed the performance records of the horses as 2- and 3-year-olds as well as the records of their maternal siblings not included in the first portion of the study. That data that revealed that foals with grades 1, 2 and 3 ossification earned about $30,000 less than their maternal siblings.

Reference: “Gestation length and racing performance in 115 Thoroughbred foals with incomplete tarsal ossification,” Equine Veterinary Journal, June 2017

This article first appeared in EQUUS #480