New Equine Fetal Health Problems Reported in Kentucky

I) Increase in the number of late term aborted foals

Starting on April 30, 2001 there have been two clinical problems reported on horse breeding farms in Kentucky. The first problem has been a dramatic increase in the number of late term aborted foals submitted to the Livestock Disease Diagnostic Center (LDCC). Since April 28, 2001, the University of Kentucky LDCC has had 318 stillborn or aborted equine foals submitted for testing. This is a 700% increase over the number of foals submitted in 2000. Most of the foals are near term, some were born alive but very weak and only survived a few days. A small number of mid to late term fetuses have also been submitted. All foals that have been submitted to the LDCC have had full diagnostic examinations performed.

To date the only remarkable finding has been some increased inflammation of the lungs. All foals were negative for nitrates/nitrites and copper, iron, zinc and selenium levels were all normal. To date the LDCC has not found any indication of equine herpes virus (1 and 4), equine arteritis virus and adenovirus. Cultures of the internal organs have given mixed results, with several different types of bacteria isolated. The placentas have been thickened and swollen. Investigators in Kentucky are looking into the possibility that fescue toxicity and/or a mycotoxin may be involved in this health problem. The aborting mares do not produce milk (agalactia) and may have difficulty in delivering the dead foal (dystocia). Mares of several different breeds have been affected.

Laboratories in Kentucky, the United Kingdom and several other states are working to find a diagnosis for this problem. At this point there are no recommendations for horse owners. If a mare in late term aborts her foal or a foal is born weak, the owner and their veterinarian should be aware of this problem. If an examination of an aborted and/or weak (dead) foal is requested, the foal and the placenta should be bagged up, kept as cool as possible and transported to the Arizona Veterinary Diagnostic Laboratory.

II) Increase in early fetal loss (EFL)

Breeding farms in central Kentucky have reported an increase in the number of mares determined to be in foal at 40 days post breeding that have experienced early fetal loss at day 45-80 of gestation. It has been observed these mares have a normal uterus on rectal palpation but ultrasound examination of the fetus shows cloudy and debris filled fluid around the fetus. This is followed by death of the fetus and expulsion of the dead fetus from the uterus. Mares with EFL have a vaginal discharge and may have a fever. It is unknown if the early fetal loss problem is in any way related to the increase in number of late term abortions. If a mare does have early fetal loss, a serum sample of the mare should be collected and with any fetal tissue that can be found sent to the Arizona Veterinary Diagnostic Laboratory.

It is very important to note these health problems have only been reported in Kentucky. Arizona horse owners should not be unduly alarmed.

This information sheet will be updated as more information is published.

If you have any questions please contact me at the Arizona Veterinary Diagnostic Laboratory.