Objective—To evaluate the diagnostic features, results of free-choice exercise treatment, prognosis, and postinjury racing performance of Thoroughbred racehorses with cumulative stress-induced bone injury (CSBI) of the distal portion of the third metacarpal and third metatarsal bones (MC3/MT3).
Design—Retrospective case series.
Animals—55 Thoroughbred racehorses with CSBI of the distal portion of MC3/MT3.
Procedures—Data on signalment, history, and radiographic, scintigraphic, and lameness examination findings were reviewed. Horses with lameness localized to the distal portion of MC3/MT3, and that did not have concurrent lameness but did have radiographic and nuclear scintigraphic changes consistent with CSBI, were included in the study. Information on pre-and postinjury racing performance was acquired from race records.
Results—Mean age was 3.2 years (median, 3 years [range, 2 to 6 years]). Ninety-five percent (52/55) of horses with CSBI raced after injury. Males were more commonly affected (75% [41/55]) than were females (25% [14/55]; odds ratio, 3.99 [95% confidence interval, 2.17 to 7.34]). There was no significant difference in postinjury total earnings, compared with total earnings before injury; horses had significantly more starts and less earnings per start after injury. Median time to first start after injury was 194 days. Of 45 horses that raced before and after injury, 31 % (14/45) had an increase in racing class, 31 % (14/45) had no change in class, and 38% (17/45) had a decrease in class.
Conclusions and Clinical Relevance—Thoroughbred racehorses with CSBI of the distal portion of MC3/MT3 treated with free-choice exercise had a favorable prognosis with no appreciable decrease in class or performance.
Objective—To compare articular cartilage from horses
with naturally developing osteochondrosis (OC)
with normal articular cartilage and healing cartilage
obtained from horses with experimentally induced
Sample Population—109 specimens of articular cartilage
from 78 horses.
Procedure—Morphologic characteristics, proteoglycan
(PG), and type II collagen were analyzed in articular cartilage
of OC specimens (group 1), matched healing cartilage
obtained 40 days after experimentally induced
osteochondral fractures (group 2), and matched normal
cartilage from the same sites (group 3).
Results—79 specimens of OC cartilage were
obtained from horses. Ex vivo PG synthesis was significantly
greater in the femoral cartilage, compared
with synthesis in the tibial cartilage, and significantly
greater for groups 1 and 2, compared with group 3.
For groups 1 and 2, femoral fragments had significantly
greater PG content, compared with PG content
in tibial fragments. Keratan sulfate content was significantly
less in group 3, compared with groups 1 and
2. Cartilage from the OC specimens had loss of structural
architecture. The OC tissue bed stained positive
for chondroitin sulfate and type II collagen, but the
fracture bed did not.
Conclusions and Clinical Relevance—Our analyses
could not distinguish articular cartilage from horses
with OC and a healing fracture. Both resembled an
anabolic, reparative process. Immunohistochemical
analysis suggested a chondromyxoid tissue in the OC
bed that was morphologically similar to fibrous tissue
but phenotypically resembled hyaline cartilage. Thus,
tissue in the OC bed may be degenerative cartilage,
whereas tissue in the fracture bed may be reparative
fibrous callus. (Am J Vet Res 2005;66:1881–1890)
Objective—To determine the effects of treatment with platelet- and leukocyte-rich plasma (PRP) on future 2-, 3-, and 4-year-old racing performance of yearling Thoroughbreds with proximal sesamoid bone inflammation and associated suspensory ligament branch (SLB) desmitis.
Design—Randomized clinical trial.
Animals—39 yearling Thoroughbreds.
Procedures—Yearling Thoroughbreds with radiographic evidence of performance-limiting proximal sesamoid bone inflammation and ultrasonographic evidence of associated SLB desmitis were identified and randomly assigned to undergo PRP (treatment group) or saline (0.9% NaCl) solution (control group) injection at the affected SLB-proximal sesamoid bone junction. Race records of horses for the 2-, 3-, and 4-year-old racing years were obtained. Data regarding amount of money earned and number of races started were used as outcome measures, and results for groups were compared.
Results—Horses treated with PRP were significantly more likely to start at least 1 race during the 2-year-old racing year than were horses treated with saline solution; no significant differences were detected between groups regarding that variable for the 3- and 4-year-old racing years. No significant differences between groups were detected regarding earnings for any racing year.
Conclusions and Clinical Relevance—Although PRP-treated horses were more likely to start a race during the 2-year-old racing year versus control group horses, results for horses in each group were not significantly different for the 3- and 4-year-old racing years. Therefore, the PRP treatment protocol evaluated in this study did not seem to improve future racing performance of yearling Thoroughbreds with proximal sesamoid bone inflammation and associated SLB desmitis, compared with injection of saline solution.