Results of bone scintigraphy in racing standardbred horses: 64 cases (1992-1994)

To document anatomic patterns of scintigraphic uptake and related orthopedic disease associated with racing activity in Standardbred horses.

Retrospective study.

64 Standardbred horses evaluated for lameness.

Medical records at the time of discharge were reviewed, and information regarding signalment; history; results of lameness examination, scintigraphy, and radiography; diagnosis; and treatment were obtained.

274 areas of increased radiopharmaceutical uptake were identified. Scintigrams of 218 limbs (106 forelimbs, 112 hind limbs) were available for review. Seventy-three (33%) scintigrams had increased radiopharmaceutical uptake associated with the proximal sesamoids, 46 of 106 (43%) fore-limb scintigrams had increased uptake associated with the third carpal bone, and 33 of 112 (33%) hind limb scintigrams had radiopharmaceutical uptake associated with the small tarsal bones. Forty-three of 218 (20%) scintigrams had increased uptake associated with the distal aspect of the third metacarpal and metatarsal bones. Abnormal scintigraphic uptake was bilateral in 91 of 139 (65%) forelimb locations and 99 of 134 (74%) hind limb locations with increased radiopharmaceutical uptake. The primary scintigraphically identified classifications of disease were exercise-induced bone remodeling, synovitis or arthritis, and soft-tissue avulsion from bone (66, 17, and 6% of areas with increased radiopharmaceutical uptake, respectively). Of 274 areas with increased radiopharmaceutical uptake, 244 (89%) were believed to be clinically important.

Distinctive patterns of increased radiopharmaceutical uptake were identified that suggested Standardbred horses used for racing may have a predilection to develop orthopedic disease at specific sites that are distinct from those in Thoroughbreds used for racing and horses used for jumping activities.