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Mare Reproductive Loss Syndrome

Livestock Disease Diagnostic Center Data as of May 8, 2001; 8:00 am

Since April 28, 2001 the University of Kentucky Livestock Disease Diagnostic Center has received 318 aborted/stillborn equine fetuses/foals for diagnostic testing/evaluation. During the same dates in the spring of 2000, the LDDC received 46 aborted/stillborn equine fetuses. This represents a nearly 700% increase in submissions of equine fetuses/stillborn foals for this time frame.

The following breeds are represented:

Thoroughbred Morgan
Standardbred Hanovarian
Tennessee Walking Horse Paso Fino
American Saddle Horse Miniature
Quarter Horse Pony
Appalossa Crossbreed - at least 3
Rocky Mountain Horse Warmblood (breed not known)
Arabian Mule

Most of the fetuses are near term. A small number of fetuses are 6-10 months gestation.  Twenty-five 2-3 months gestation have been received.

Examinations of the fetuses and testing of appropriate specimens are being done by professional and technical staff who are specialists in essential disciplines in veterinary diagnostic laboratory medicine. Specialists involved are pathologists, bacteriologists, serologists, toxicologists and virologists. All cases are assigned to one of the program's veterinary pathologists who is the case coordinator and is responsible for doing the necropsy, histopathological evaluation and collating the information into a written case summary.

Necropsy examinations have demonstrated some pulmonary changes primarily firmer dark lungs. This has been the only remarkable observation made on gross examination. Preliminary histopathological examinations of the lungs show mild inflammation in a small number of fetuses/foals.

Toxicological examinations:
Fetuses tested for nitrates/nitrites have been negative. Copper, iron, zinc and selenium levels in mare sera have been normal.

Virologic examinations:
All samples tested to date are negative for equine herpes virus 1 and 4, equine arteritis virus and adenovirus. Attempts to isolate an "unknown" virus are in progress.

Bacteriologic examinations:
Aerobic cultures of internal organs have given the following results:
Fetuses tested 161 (late term 154, early stage 7)
Actinobacillus equuli 45
Streptococcus spp 75
A. equuli and Streptococcus 2
Streptococcus zooepidemicus 2
Staphylococcus sp 1
Coliforms 3

Fluorescent antibody tests are negative for leptospirosis.

--Lenn R. Harrison, VMD, Director, Livestock Disease Diagnostic Center, Veterinary Science Department, College of Agriculture, University of Kentucky .

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