Objective - To describe the incidence and types of gross osseous developmental variations and ages of physeal closure in the caudal portion of the thoracic and lumbosacral spine and the pelvis in a sample of Thoroughbred racehorses. Animals - Thoroughbred racehorses (n = 36) that died or were euthanatized at California racetracks between October 1993 and July 1994. Procedure - Lumbosacropelvic specimens were collected, and all soft tissues were removed. The osseous specimens were visually examined. Results - Only 22 (61 %) specimens had the expected number of 6 lumbar and 5 sacral vertebrae. Eight (22%) specimens had thoracolumbar transitional vertebrae, and 13 (36%) had sacrocaudal transitional vertebrae. Articular process asymmetries were present at 1 or more vertebral segments in 30 (83%) specimens. Intertransverse joints (2 to 4 pairs/specimen) were bilaterally distributed in the caudal portion of the lumbar spine and the lumbosacral joint in 31 (86%) specimens. Five (14%) specimens had asymmetric distribution of the intertransverse joints. Intertransverse joint ankylosis was found in 10 (28%) specimens. Lumbosacral vertebral body physeal closure occurred between 4.9 and 6.7 years of age; pelvic physeal closure occurred between 5.2 and 5.8 years of age. Iliac crest and ischial arch epiphyseal formation was evaluated, using a grading system, and fusion to the underlying bone occurred at 7.2 years and 5.4 years of age, respectively. Conclusions - Numerous vertebral anatomic variations were commonly found in a sample of Thoroughbred racehorses. Clinical Relevance - Normal anatomic variations and ages of skeletal maturity need to be considered in clinical evaluation of the equine spine and pelvis for differentiation from pathologic findings.
|Original language||English (US)|
|Number of pages||9|
|Journal||American Journal of Veterinary Research|
|State||Published - Oct 1997|
ASJC Scopus subject areas