Stress remodeling and stress fracture of the humerus in four standardbred racehorses.
Two 2-year-old pacers, a 3-year-old pacer and a 2-year-old-trotter with acute forelimb lameness were admitted for nuclear scintigraphic examination. Horses were grade 3-4/5 lame. There was increased radiopharmaceutical uptake (IRU) in the distal cranial medial aspect of the humerus in one horse and along the caudal humeral cortex in the other three horses. Two of the four horses were affected bilaterally. Radiographic abnormalities consisted of thickening of the caudal cortex of the mid-diaphysis of the humerus but radiographic changes were not present in all horses. All horses were managed with stall rest initially then stall rest with hand-walking followed by limited turn out for a total of four months. None of the horses had raced before injury. One horse has returned to race training and the other three horses have returned to racing. Average time to return to racing was 329 days. Humeral stress fractures in Standardbred horses are rare. Diffuse patterns of IRU have not been reported in the humerus and are likely indicative of severe stress remodeling. Standardbred racehorses with stress fractures or stress remodeling of the humerus appear to have a good prognosis for return to racing.
Kraus
Beth M
BM
Department of Clinical Studies, New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, 382 West Street Road, Kennett Square, PA 19348, USA. bkraus@vet.upenn.edu
Ross
Michael W
MW
Boswell
Robert P
RP
D000818:Animals; D005260:Female; D015775:Fractures, Stress / Q000000981:diagnostic imaging / Q000662:veterinary*; D006736:Horses / Q000293:injuries*; D006810:Humeral Fractures / Q000000981:diagnostic imaging / Q000662:veterinary*; D007794:Lameness, Animal / Q000000981:diagnostic imaging / Q000209:etiology*; D011859:Radiography; D011877:Radionuclide Imaging