Scapula Stress Fractures in Eight Thoroughbred Racehorses

Scapula stress fractures were seen in Thoroughbred racehorses displaying acute moderate forelimb lameness. Nuclear scintigraphy identified the junction of the middle and distal one-third scapula spine and/or scapula supraspinous fossa as predilection sites for scapula stress fractures. Conservative management resulted in a good prognosis for return to racing, but stress-fracture recurrence may be seen.

1. Introduction

The purpose of this study was to review the clinical findings and outcome of eight horses diagnosed with scapula stress fractures.

2. Materials and Methods

The medical records and diagnostic images of all horses diagnosed as having scapula stress fractures between 1997 and 2006 were reviewed. Follow-up was performed by clinical examination, nuclear scintigraphic examination, telephone inquiry, and racerecord analysis.

3. Results

Eight cases (median age = 3 yr; six geldings, one colt, and one filly) were examined for acute forelimb lame-tively by restricted exercise for 3 mo. Six horses have ness (median grade 3 of 5; range = 2 - 4 on the Amer-returned to racing (mean time to return to racing ican Association of Equine Practitioner lameness scale post-injury = 9.8 ± 4.1 mo; mean number of starts from 0 to 5). All cases were in race training at the post-injury = 13 ± 9.7; prize money per start before time of the onset of lameness, and two of eight horses injury = $3900 ± 5515.4; prize money per start after conservative management = $3446.1 ± 4331.4). One horse has not returned to racing because of stress-fracture recurrence at the initial site and is currently convalescing. The owner of the other horse elected to retire the horse to stud. Of the seven horses that returned to training, two experienced recurrent scapular stress fractures at the initial site of injury.

4. Discussion

To the authors’ knowledge, a series of scapula stress fractures of the mid-distal scapula spine and/or supraspinous fossa have not been reported. Scapula stress fractures resulted in an acute moderate forelimb lameness that was seen in Thoroughbred horses undertaking strenuous exercise (≈16 m/s). Bone-phase nuclear scintigraphy was integral to the diagnosis, and ultrasonography may be beneficial to image the fracture. Conservative management resulted in a good prognosis for racing return; however, recurrence at the initial scapular stress-fracture site was seen in ≈28% of cases.