Comparison of the racing performance of Thoroughbreds with versus without osteochondral fragmentation of the accessory carpal bone identified on yearling sales repository radiographs.

This research investigated the race performance of young Thoroughbred racehorses with and without osteochondral fragmentation of the accessory carpal bone (ACB), a condition identified through presale radiographs. The findings suggested that there are no significant differences in performance between horses with or without this condition, including when there are concurrent carpal osteoarthritis or other radiographic abnormalities.

Study Design

• The research was designed as a retrospective, matched cohort study where Thoroughbred racehorses with the ACB condition (called the exposed cohort) and those without it (unexposed cohort) were compared.
• The study sample consisted of 47 nonlame Thoroughbreds with the ACB condition and 94 similar horses without this bone fragmentation.
• Radiographic interpretation reports from a large Kentucky auction house, along with race records, were gathered and studied to analyze the impact of ACB on performance in Thoroughbred racehorses.

Procedure

• The researchers reviewed radiographic interpretation reports for Thoroughbreds involved in September yearling sales at a large Kentucky auction house between 2005 and 2012.
• They then collected and analyzed the racing records of these horses.
• The main objective was to compare the race performance of horses with and without ACB from the same sale and identify possible associations.

Findings

• The researchers found no significant differences in the incidence of starting a race as a 2- or 3-year-old and the number of races started, earnings, or earnings per start for 2- or 3-year-old, or career race performance amongst the tested Thoroughbreds, irrespective of the presence of the ACB condition.
• Performance did not differ substantially between horses with ACB alone and those with ACB fracture accompanied by other radiographic abnormalities that earlier studies linked to poorer performance.

Conclusions and Clinical Relevance

• The research concluded that the presence of ACB fractures, whether paired with carpal osteoarthritic changes or not, was not associated with poorer racing performance or a less likely probability of starting a race as a 2- or 3-year-old.
• This implicates that ACB, as identified through repository radiographs of Thoroughbred yearlings, might not be a critical factor in determining future performance in racing events, thus reducing concerns related to presale radiographs identifying this condition.