Racing performance of Thoroughbreds with superficial digital flexor tendonitis treated with desmotomy of the accessory ligament of the superficial digital flexor tendon: 332 cases (1989-2003).

The study investigates the impact and effectiveness of a surgical treatment (superior check ligament desmotomy, or SCLD) on Thoroughbred racehorses suffering from a common tendonitis condition, with outcomes being evaluated in terms of return to racing, rate of post-operative infections, time to first race after surgery, and career longevity.

Research Design and Methodology

• The study utilised a retrospective case series design, investigating 332 Thoroughbred racehorses that had been suffering from moderate to severe superficial digital flexor tendonitis (SDFT), which is an overuse injury in horses affecting the forelimbs. These horses were treated with superior check ligament desmotomy (SCLD), a particular surgical procedure.
• Data was gathered from medical records and racing histories to determine the likelihood of return to racing, number of races completed, the duration before the first race post-treatment, and the career longevity of the horses. The horses were classified as having raced or not raced prior to and after the surgery.

Results of the Study

• Out of 332 horses treated with SCLD, 228 (69%) returned to competitive racing post-injury and surgery, including 78 out of 118 that hadn’t raced prior to injury and 150 out of 214 horses that did. This suggested a notable success rate for the treatment.
• Among horses aged 5 or older, 44% out of 39 made a successful return to racing compared to the much higher percentage of 72% returns in younger horses (age ≤ 4). Older horses were significantly less likely to return to racing, establishing age as an important factor influencing treatment success. The rate of return to races remained constant in 2-, 3- and 4-year olds.
• Postoperative infections were rare, affecting only 2% (6 out of 332) of the treated horses.
• Median time until the first race after surgery was around 302 days, and each treated horse participated in a median of 8 races following surgery. Out of the 228 horses that returned to racing, 159 (70%) completed at least 5 races post-surgery. Regardless of the sex and treated limb of the horse, the likelihood of return to racing was not significantly affected.
• There was no substantial difference in return-to-racing rates between the horses treated bilaterally (both the affected and contralateral) and the ones treated unilaterally, in cases of unilateral SDFT.

Conclusion and Impact

• The study found that SCLD treatment helped 69% of horses with SDFT return to racing. These horses also underwent a shorter convalescence period than earlier reported, and had longer racing careers post-surgery than proposed for other treatments.
• These findings bolster the idea of including SCLD in treatment plans for racehorses suffering from SDFT.