Objective—To determine major causes of death and the anatomic location of musculoskeletal injuries in Quarter Horse racehorses in California.
Design—Retrospective case series.
Animals—314 Quarter Horse racehorses with musculoskeletal injuries that were necropsied through the California Horse Racing Board Postmortem Program from 1990 to 2007.
Procedures—Postmortem pathology reports were retrospectively reviewed. Musculoskeletal injuries were categorized by anatomic region and described. The number of Quarter Horse starts and starters for the same period of time were obtained from a commercial database for determination of fatal injury incidence.
Results—Musculoskeletal injuries accounted for 314 of the 443 (71 %) Quarter Horse racehorses that died during the 18-year study period. Fatal musculoskeletal injuries occurred at a rate of 2.0 deaths/1,000 race starts and 18.6 deaths/1,000 horses that started a race. Musculoskeletal injuries occurred predominantly during racing (84%) and in the forelimbs (81%). The most common fatal musculoskeletal injuries were metacarpophalangeal and metatarsophalangeal joint (fetlock) support injuries (40%) and carpal (24%), vertebral (10%), and scapular (8%) fractures. Proximal interphalangeal (pastern) joint luxations resulted in death of 3% of horses. Fracture configurations of some bones were consistent with those of Thoroughbred racehorses. Evidence of preexisting stress remodeling of bone was reported for some fractures.
Conclusions and Clinical Relevance—Knowledge of common locations and types of fatal musculoskeletal injuries in racing Quarter Horses may enhance practitioners' ability to detect mild injuries early, rest horses, and help prevent catastrophic injuries.
Objective—To determine sensitivity and specificity of
western blot testing (WBT) of CSF and serum for diagnosis
of equine protozoal myeloencephalitis (EPM) in
horses with and without neurologic abnormalities.
Animals—65 horses with and 169 horses without
Procedure—CSF and serum from horses submitted
for necropsy were tested for Sarcocystis neuronaspecific
antibody with a WBT. Results of postmortem
examination were used as the gold standard against
which results of the WBT were compared.
Results—Sensitivity of WBT of CSF was 87% for horses
with and 88% for horses without neurologic abnormalities.
Specificity of WBT of CSF was 44% for horses
with and 60% for horses without neurologic abnormalities.
Regardless of whether horses did or did not have
neurologic abnormalities, sensitivity and specificity of
WBT of serum were not significantly different from values
for WBT of CSF. Ninety-four horses without EPM
had histologic evidence of slight CNS inflammation.
Conclusions and Clinical Relevance—The low
specificity of WBT of CSF indicated that it is inappropriate
to diagnose EPM on the basis of a positive test
result alone because of the possibility of false-positive
test results. The high sensitivity, however, means that
a negative result is useful in ruling out EPM. There was
no advantage in testing CSF versus serum in horses
without neurologic abnormalities. Slight CNS inflammation
was common in horses with and without S
neurona-specific antibodies in the CSF and should not
be considered an indication of CNS infection with S
neurona. (J Am Vet Med Assoc 2002;221:1007–1013)
Objective—To determine the distribution for limbs and bones in horses with fractures of the proximal sesamoid bones and relationships with findings on palmarodorsal radiographic images.
Sample Population—Proximal sesamoid bones obtained from both forelimbs of cadavers of 328 racing Thoroughbreds.
Procedure—Osteophytes; large vascular channels; and fracture location, orientation, configuration, and margin distinctness were categorized by use of high-detail contact palmarodorsal radiographs. Distributions of findings were determined. Relationships between radiographic findings and fracture characteristics were examined by use of χ2 and logistic regression techniques.
Results—Fractures were detected in 136 (41.5%) horses. Biaxial fractures were evident in 109 (80%) horses with a fracture. Osteophytes and large vascular channels were evident in 266 (81%) and 325 (99%) horses, respectively. Medial bones typically had complete transverse or split transverse simple fractures, indistinct fracture margins, > 1 vascular channel that was > 1 mm in width, and osteophytes in abaxial wing and basilar middle or basilar abaxial locations. Lateral bones typically had an oblique fracture and distinct fracture margins. Odds of proximal sesamoid bone fracture were approximately 2 to 5 times higher in bones without radiographic evidence of osteophytes or large vascular channels, respectively.
Conclusions and Clinical Relevance—Biaxial fractures of proximal sesamoid bones were common in cadavers of racing Thoroughbreds. Differences between medial and lateral bones for characteristics associated with fracture may relate to differences in fracture pathogeneses for these bones. Osteophytes and vascular channels were common findings; however, fractures were less likely to occur in bones with these features.