Leptospirosis in Mares and Abortion

by Robert N. Oglesby DVM

For more information on this topic see: Placentitis in Mares

Leptospirosis in a horse

Posted by Jan
I have a young broodmare who has tested positive for lepto. It seems that there is a lot of disagreement as to the chances of her passing this disease onto her foal in utero. Last year, rather than euthanizing her (she has lost her sight), I decided to take a chance and breed her one more time. Now that foaling time is drawing near, I was hoping to find some accurate information regarding care and treatment of the foal. Is there a vaccine that can be given the baby to prevent contraction of lepto, assuming it tests negative? I have heard that a cow vaccine would do no harm. Apparently very little study has been done on this subject, and I really hate to put this mare down if there is a way to deal with her problem.

The mare is now 11 yrs and is due to foal on or about April 10. She lost sight in one eye due to trauma, but when she developed chronic uveitis in the other eye, the vet thought he would test her. She tested positive through a blood titer, but the vet said that many horses will test positive. Basically, no big deal. She was tested again, about a year later and found to have a raging case of lepto, this was verified with urine test. Apparently the levels were many times greater than what is to be acceptable.

Last year she lost a foal at 4 days. He was born without incident but never really seemed "right". A necropsy was done and all of his organs were yellow. Test results concluded septicemia. We re-bred the mare at 30 days and she settled on the first breed. She has now gone totally blind and is isolated in a 100x100 paddock with her "seeing eye goat". This is a quarter horse mare, 1485 pounds, 16hh. Her foal weighed 185 at birth. That in itself is a bit unusual for a qh. The mare's foal was not checked for IgG. His post mortem report indicated that no lepto was present. Histopath indicated incomplete development of the liver and no isolates. The mare did not show any signs of depression, fever, poor appetite, or any other symptoms until she lost her foal, at which time she lost a great deal of weight and fretted continually. She started pacing circles, but she continued to eat. This went on for about a month. Her tests showed the following results: Positive interpretation of: Lepto.grippo 1:400 Lepto.hardjo 1:100 Lepto.pomona 1:1600 Lepto.ictero 1:800

This report consists of the reply Dr. Oglesby wrote to this inquiry.