Evaluation of early fetal losses on four equine farms in central Kentucky: 73 cases (2001).
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.


METHODS
Retrospective study.


METHODS
288 pregnant broodmares.


METHODS
Year-2001 breeding records for 288 Thoroughbred broodmares were examined. Early fetal loss was defined as loss of a fetus that was viable at > or = 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
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.
Morehead
James P
JP
Equine Medical Associates PSC, Lexington, KY 40511, USA.
Blanchard
Terry L
TL
Thompson
James A
JA
Brinsko
Steven P
SP
D000367:Age Factors; D000818:Animals; D005260:Female; D005313:Fetal Death / Q000453:epidemiology / Q000662:veterinary*; D006736:Horses / Q000502:physiology*; D007629:Kentucky / Q000453:epidemiology; D010298:Parity; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000662:veterinary*; D011270:Pregnancy, Animal / Q000502:physiology*; D012189:Retrospective Studies; D012307:Risk Factors; D012621:Seasons