Evaluation of forelimb horseshoe characteristics of Thoroughbreds racing on dirt surfaces

Objective - To describe forelimb horseshoe characteristics of horses racing on dirt surfaces and determine whether these characteristics vary with region of California, season, horse characteristics, and race-related factors. Animals - 5,730 Thoroughbred racehorses. Procedure - From June 17, 2000, to June 16, 2001, the characteristics of 1 forelimb horseshoe of horses that raced on dirt surfaces at 5 major racetracks in California were recorded. These characteristics included shoe type; toe grab height; and presence of a rim, pad, and heel traction devices (jar caulks, heel stickers, heel blocks, and special nails). Horse and race information was obtained from commercial records. One race/horse was randomly selected. Results - 99% of forelimb horseshoes were aluminum racing plates, 35% had a pad, 23% had a rim, and 8% had a heel traction device. A toe grab was observed on 75% of forelimb horseshoes (14% very low [≤ 2 mm], 30% low [> 2 and ≤ 4 mm], 30% regular [> 4 and ≤ 6 mm], and 1% high [> 6 and ≤ 8 mm]). Forelimb horseshoe characteristics varied with region of California, season, age and sex of the horse, race purse and distance, and track surface condition. Log-linear modeling revealed that all of these factors were significantly interrelated. Conclusions and Clinical Relevance - Complex interrelationships among forelimb horseshoe characteristics and region, season, age and sex of the horse, and race-related factors need to be considered when evaluating the relationships between injury and horseshoe characteristics in Thoroughbred racehorses.