Case-control study of late-term abortions associated with mare reproductive loss syndrome in central Kentucky.
OBJECTIVE
To identify factors associated with abortions of mares during late gestation attributed to mare reproductive loss syndrome (MRLS).


METHODS
Case-control study.


METHODS
282 broodmares from 62 farms in central Kentucky, including 137 mares that had late-term abortions (LTAs) associated with MRLS, 98 mares from the same farms that did not abort, and 48 mares that aborted from causes other than MRLS.


METHODS
Farm managers were interviewed to obtain data on a wide range of management practices and environmental exposures for the mares. Data for case and control horses were compared to identify risk factors for a mare having a MRLS-associated LTA (MRLS-LTA).


RESULTS
Several factors increased the risk of mares having MRLS-LTAs, including increased amount of time at pasture, less time in a stall, feeding concentrate on the ground, higher proportion of diet derived from grazing pasture, being fed in pasture exclusively during the 4-week period prior to abortion, access to pasture after midnight during the 4-week period prior to abortion, and drinking from a water trough or not having access to water buckets or automatic waterers.


CONCLUSIONS
Analysis indicates that exposure to pasture predisposed mares to having MRLS-LTAs and stillborn foals. Methods for limiting exposure to pasture (keeping mares in stalls longer) during environmental conditions similar to those seen in 2001 should reduce the risk of mares having MRLS-LTAs.
Cohen
Noah D
ND
Department of Large Animal Medicine and Surgery, College of Veterinary Medicine, Texas A&M University, College Station, TX 77843-4475, USA.
Carey
Vincent J
VJ
Donahue
James G
JG
Seahorn
Janyce L
JL
Donahoe
Judith K
JK
Williams
Deborah M
DM
Harrison
Lenn R
LR
D000034:Abortion, Veterinary / Q000453:epidemiology / Q000209:etiology*; D000821:Animal Feed; D000822:Animal Husbandry / Q000379:methods*; D000818:Animals; D016022:Case-Control Studies; D005260:Female; D006734:Horse Diseases / Q000453:epidemiology* / Q000209:etiology; D006736:Horses; D006799:Housing, Animal; D007629:Kentucky / Q000453:epidemiology; D006109:Poaceae / Q000009:adverse effects; D011247:Pregnancy; D012189:Retrospective Studies; D012307:Risk Factors; D013577:Syndrome