Impact of colic surgery on return to function in racing Thoroughbreds: 59 cases (1996-2009).

The study looks into how colic surgery affects the racing performance of Thoroughbred horses, determining the clinical factors that contribute to a successful return to racing and comparing the post-surgery performance to that of untreated horses.

Research Method

• A retrospective cohort study method was employed for this research.
• The study involved 59 Thoroughbred racehorses, aged between 2 to 5 years, which had undergone colic surgery and survived to discharge from the hospital.
• For comparison, 90 untreated Thoroughbred racehorses of equivalent class were studied.
• The researchers used medical records of horses evaluated for colic between January 1996 and July 2009. The selection criteria included horses having a Jockey Club Information Systems record.
• Data recorded included physical examination and laboratory findings at admission, lesion location and type, the length of surgery, hospitalization duration, and any post-operative complications.
• The untreated cohort comprised two untreated horses randomly picked from runners in each treated horse’s last race immediately before their colic surgery.
• The performance analysis included only those horses which had raced at least once before and after the surgery.

Data Analysis

• Earnings and the number of starts per race for each horse were determined from racing records.
• These parameters were compared between treated and untreated horses for the 12 quarters following the surgery.
• A Wilcoxon rank sum test was used for this comparison.
• The longevity of a horse’s racing career was assessed with a survival analysis.
• Through a Poisson regression, rates of return to racing and the number of active quarters in the first 12 quarters post-surgery were compared between treated and untreated horses.

Results

• 76% of the horses that raced prior to the surgery returned to racing.
• The likelihood of a successful return to racing was significantly related to the admission heart rate and blood lactate concentration.
• Between the 3rd and 12th quarters post-surgery, both the treated and untreated horses showed slight differences in the number of starts but no difference in earnings per quarter.
• Overall, there was no notable difference in the total number of quarters raced, the number of starts, or earnings after surgery between the treated and untreated horses.
• Compared to the untreated horses, the treated ones had higher earnings per start.

Conclusions

• The study concluded that – providing they successfully return to racing – Thoroughbred horses that undergo colic surgery show no significant differences in their performance when compared to untreated horses.