Stress fractures of the tibia and humerus in Thoroughbred racehorses: 99 cases (1992-2000).
OBJECTIVE
To determine clinical characteristics of and outcome in Thoroughbred racehorses with tibial or humeral stress fractures.


METHODS
Retrospective study.


METHODS
99 Thoroughbreds with tibial or humeral stress fractures.


METHODS
Information obtained from the medical records included history, signalment, and clinical, radiographic, and scintigraphic findings. Outcome was determined by interviewing trainers, performing follow-up examinations, and analyzing race records.


RESULTS
Seventy-four tibial stress fractures were identified in 61 Thoroughbreds, and 48 humeral stress fractures were identified in 39 Thoroughbreds (1 horse was included in both groups). Tibial stress fractures occurred most commonly in 2-year-old or unraced horses. Fractures were located in 1 of 3 sites in the tibia (most commonly, the caudolateral cortex of the mid-diaphysis) and 1 of 4 sites in the humerus (most commonly, the caudodistal cortex). Forty-four of 58 (76%) tibial stress fractures and 18 of 32 (56%) humeral stress fractures were identified radiographically. Humeral stress fractures involving the caudodistal cortex were not detected radiographically. Treatment consisted of rest and exercise restriction, and 49 of 61 (80%) horses with tibial stress fractures and 30 of 39 (77%) horses with humeral stress fractures returned to racing. Humeral stress fractures recurred in 6 horses.


CONCLUSIONS
Results suggested that in Thoroughbred racehorses, tibial stress fractures occurred most commonly in unraced 2 year olds, whereas humeral fractures occurred most commonly in older horses that had raced previously. The prognosis for racing following treatment was good.
O'Sullivan
Christopher B
CB
Randwick Equine Centre, 3 Jane St, Randwick, NSW 2035, Australia.
Lumsden
Jonathan M
JM
D000367:Age Factors; D000818:Animals; D015775:Fractures, Stress / Q000000981:diagnostic imaging / Q000628:therapy / Q000662:veterinary*; D006736:Horses / Q000293:injuries*; D006810:Humeral Fractures / Q000000981:diagnostic imaging / Q000628:therapy / Q000662:veterinary*; D007794:Lameness, Animal / Q000209:etiology; D010805:Physical Conditioning, Animal; D011379:Prognosis; D011859:Radiography; D011877:Radionuclide Imaging; D012008:Recurrence; D012146:Rest; D012189:Retrospective Studies; D013177:Sports; D013978:Tibial Fractures / Q000000981:diagnostic imaging / Q000628:therapy / Q000662:veterinary*; D016896:Treatment Outcome