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  • Author or Editor: Stuart E. Brown II x
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Abstract

Objective—To characterize the temporality of dates of breeding and abortion classified as mare reproductive loss syndrome (MRLS) among mares with abortions during early gestation.

Animals—2,314 mares confirmed pregnant at approximately 28 days after breeding from 36 farms in central Kentucky, including 515 mares that had earlyterm abortions.

Procedure—Farm veterinarians and managers were interviewed to obtain data for each mare that was known to be pregnant to determine pregnancy status, breeding date, last date known to be pregnant, and date of abortion.

Results—Mares bred prior to April 1, 2001, appeared to be at greatest risk of early-term abortion, both among and within individual farms. Mares bred in mid-February appeared to be at greatest risk of abortion, with an estimated weekly incidence rate of abortion of 66% (95% CI, 52% to 80%).

Conclusions and Clinical Relevance—Mares in central Kentucky bred between mid-February and early March were observed to be at greatest risk of early-term abortion, and risk gradually decreased to a background incidence of abortion of approximately 11%. Mares bred after April 1, 2001, appeared to be at markedly less risk, indicating that exposure to the cause of MRLS likely occurred prior to this date. (Am J Vet Res 2005;66:1792–1797)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To estimate spatial risks associated with mare reproductive loss syndrome (MRLS) during 2001 among horses in a specific study population and partition the herd effects into those attributable to herd location and those that were spatially random and likely attributable to herd management.

Animals—Pregnant broodmares from 62 farms in 7 counties in central Kentucky.

Procedure—Veterinarians provided the 2001 abortion incidence proportions for each farm included in the study. Farms were georeferenced and data were analyzed by use of a fully Bayesian risk-mapping technique.

Results—Large farm-to-farm variation in MRLS incidence proportions was identified. The farm-to-farm variation was largely attributed to spatial location rather than to spatially random herd effects

Conclusions and Clinical Relevance—Results indicate that there are considerable data to support an ecologic cause and potential ecologic risk factors for MRLS. Veterinary practitioners with more detailed knowledge of the ecology in the 7 counties in Kentucky that were investigated may provide additional data that would assist in the deduction of the causal factor of MRLS via informal geographic information systems analyses and suggest factors for inclusion in further investigations. (Am J Vet Res 2005;66:17–20)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To identify factors associated with abortions during early gestation classified as mare reproductive loss syndrome (MRLS).

Design—Case-control study.

Animals—324 broodmares from 43 farms in central Kentucky, including 121 mares from 25 farms that had early-term abortions (ETAs) associated with MRLS (case horses), 120 mares from the same farms but that did not abort, and 83 mares from 18 farms that were not severely impacted by MRLS.

Procedure—Farm managers were interviewed to obtain data on various management practices and environmental exposures for the mares. Data for case and control horses were compared to identify risk factors for mares having MRLS-associated ETAs.

Results—Several factors increased the risk of MRLS-associated ETAs, including feeding hay in pasture, greater than usual amounts of white clover in pastures, more eastern tent caterpillars in pastures, abortion during a previous pregnancy, and sighting deer or elk on the premises.

Conclusions and Clinical Relevance—Analysis indicates that certain characteristics of pastures predisposed mares to MRLS-associated ETAs. Methods for limiting exposure to pasture (keeping mares in stalls longer) during environmental conditions similar to those of 2001 (ie, sudden freezing in mid-April following warmer-than-usual springtime temperatures and larger-than-usual numbers of eastern tent caterpillars in and around pastures) should reduce the risk of mares having MRLS-associated ETAs. It was not possible to determine whether exposure to white clover or caterpillars were causal factors for MRLS or were merely indicators of unusual environmental conditions that resulted in exposure of mares to a toxic or infectious agent. (J Am Vet Med Assoc 2003;222:210–217)

Restricted access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine whether the concentration of airborne virulent Rhodococcus equi varied by location (stall vs paddock) and month on horse farms.

Sample—Air samples from stalls and paddocks used to house mares and foals on 30 horse breeding farms in central Kentucky.

Procedures—Air samples from 1 stall and 1 paddock were obtained monthly from each farm from January through June 2009. Concentrations of airborne virulent R equi were determined via a modified colony immunoblot assay. Random-effects logistic regression was used to determine the association of the presence of airborne virulent R equi with location from which air samples were obtained and month during which samples were collected.

Results—Of 180 air samples, virulent R equi was identified in 49 (27%) and 13 (7%) obtained from stalls and paddocks, respectively. The OR of detecting virulent R equi in air samples from stalls versus paddocks was 5.2 (95% confidence interval, 2.1 to 13.1). Of 60 air samples, virulent R equi was identified in 25 (42%), 18 (30%), and 6 (10%) obtained from stalls during January and February, March and April, and May and June, respectively. The OR of detecting virulent R equi from stall air samples collected during May and June versus January and February was 0.22 (95% confidence interval, 0.08 to 0.63).

Conclusions and Clinical Relevance—Foals were more likely to be exposed to airborne virulent R equi when housed in stalls versus paddocks and earlier (January and February) versus later (May and June) during the foaling season.

Full access
in American Journal of Veterinary Research