Objective—To determine features of an early fetal
loss (EFL) syndrome and evaluate potential risk factors
for EFL in Thoroughbred broodmares on 4 farms
in central Kentucky.
Animals—288 pregnant broodmares.
Procedure—Year-2001 breeding records for 288
Thoroughbred broodmares were examined. Early
fetal loss was defined as loss of a fetus that was
viable at ≥ 40 days of gestation but was subsequently
lost by 5 months of gestation.
Results—Overall 2001 EFL rate was 25% (73/288),
median gestational age at time of fetal loss was 77
days, and median date of loss was May 7. Mares on
1 farm had significantly fewer fetal losses (5%) than
mares on the other 3 farms (26 to 35%). Fetal losses
were higher for maiden (42%) and barren (42%)
mares than for foaling mares (18%). Fetal losses
were greater in young than in older mares. Effects of
broodmare farm, mare age, and reproductive status
were all significant. Fetal losses were not associated
with sire used for mating or stud farm.
Conclusions and Clinical Relevance—Greatest risk
for EFL occurred during the period from late April to
May (ie, in mares bred during February through
March). Higher incidence of EFL in maiden and barren
mares and lower incidence of EFL on 1 farm suggest
management or environmental influences may have
affected outcome. Risk factors that should be investigated
include environmental differences among
farms and differences in management procedures
used for lactating versus nonlactating mares. (J Am
Vet Med Assoc 2002;220:1828–1830)
Objective—To compare endoscopic findings of the
upper portion of the respiratory tract in Thoroughbred
yearlings with their subsequent race records to determine
whether subjective assessment of airway function
may be used as a predictor of future racing performance.
Animals—427 Thoroughbred yearlings.
Procedures—Endoscopic examination findings were
obtained from the medical records and the videoendoscopic
repository of the Keeneland 1996
September yearling sales. Racing records were
requested for the yearlings through the end of their 4-year-old racing season (1997–2000). Twenty-nine measures
of racing performance were correlated with
endoscopic findings. Subjective arytenoid cartilage
movement grades were determined, using a 4-point
grading scale (grade 1 = symmetrical synchronous
abduction of the arytenoid cartilages; grade 4 = no
substantial movement of the left arytenoid cartilage).
Results—Of the 427 Thoroughbred yearlings included
in this study, 364 established race records, and 63 did
not. Opinions regarding suitability for purchase, meeting
conditions of the sale, and the presence of
epiglottic abnormalities had no significant association
with racing performance. Arytenoid cartilage movement
grades were significantly associated with many
of the dependent variables. However, palatine abnormalities
were not predictive of inferior racing performance.
Conclusions and Clinical Relevance—Thoroughbred
yearlings with grade-1 and -2 arytenoid cartilage
movements had significantly better racing performance
as adults, compared with yearlings with grade-
3 arytenoid cartilage movements. In contrast, epiglottic
and palatine abnormalities were not predictive of
inferior racing performance. Therefore, evaluation of
laryngeal function, but not epiglottic or palatine abnormalities,
using the 4-point grading system, should be
the major factor in developing recommendations for
prospective buyers. (J Am Vet Med Assoc 2001;219:
Objective—To determine whether administration of
killed West Nile virus vaccine was associated with
pregnancy loss among broodmares.
Design—Retrospective cohort study.
Procedure—Records of pregnant mares with known
vaccination history from 4 farms were reviewed.
Information obtained from 595 mares included mare's
identification; farm; age; breed; reproductive status;
last breeding date; date last known pregnant; vaccination
date; age of conceptus at vaccination; vaccination
during the early embryonic, early fetal, and late fetal
periods; and whether an early embryonic death (EED),
early fetal loss (EFL), or late fetal loss (LFL) occurred.
The relationships between the dichotomous outcomes
of loss (eg, EED, EFL, LFL) and independent categoric
variables (eg, vaccination during the early embryonic,
early fetal, or late fetal periods) were examined.
Results—Vaccination of pregnant mares during any
period of gestation was not associated with increased
incidence of pregnancy loss.
Conclusions and Clinical Relevance—Many mares
are already pregnant at the onset of mosquito season,
when mares are more likely to be vaccinated than at
other times. Our findings provide evidence that vaccine
administration will not compromise pregnancy in
horses. (J Am Vet Med Assoc 2004;225:1894–1897)
OBJECTIVE To evaluate 2- and 3-year-old and career race performance of Thoroughbred racehorse prospects with and without osteochondral fragmentation of the accessory carpal bone (ACB) identified on yearling presale radiographs.
DESIGN Retrospective, matched cohort study.
ANIMALS 47 nonlame Thoroughbreds with (exposed cohort) and 94 nonlame Thoroughbreds without (unexposed cohort) osteochondral fragmentation of ACB facture identified on yearling sales repository radiographs.
PROCEDURES Repository radiographic interpretation reports for September yearling sales of a large Kentucky auction house from 2005 through 2012 were reviewed, and race records were collected and analyzed. Race performance was compared between horses with and without ACB fracture chosen from the same sale to identify associations between racing performance and ACB fracture.
RESULTS No significant differences were identified between horses with or without ACB fracture in their incidence of starting a race as a 2- or 3-year-old and the number of races started, earnings, or earnings per start for 2- or 3-year-old or career race performance. There was no significant difference in performance between horses with or without concurrent carpal osteoarthritis, nor did performance differ between horses with ACB fracture alone and those with ACB fracture and other radiographic abnormalities found to be associated with poorer performance in previous studies.
CONCLUSIONS AND CLINICAL RELEVANCE ACB fracture with or without carpal osteoarthritic changes identified on repository radiographs of Thoroughbred yearlings was not associated with poorer racing performance or lower likelihood of starting a race as a 2- or 3-year-old, compared with outcomes for unaffected horses.