Q & A – Milking Mares

Published in the March 2008, edition of the Western Horse Review.

Dr. David Ramey, DVM, is a graduate of Colorado State University. After completing an internship in equine medicine and surgery at Iowa State University, he entered a private equine practice in southern California in 1984. Dr. Ramey is a noted author and lecturer. Here he answers our reader\’s question on their brood mare. Visit him online at www.horseandriderbooks.com/david_ramey.html

Question: I have an open mare that milks up every spring and summer. She is older and has carried several foals to term, but has also lost a couple. Can you tell me why this happens and if there is any way to stop it?

Answer: The mammary glands of the mare are under the control of various hormones secreted by glands in the horse’s body. Older horses may develop benign growths of their pituitary glands, causing a condition called pars pituitary intermedia dysfunction (PPID), which is more commonly known as Cushing’s Disease. Older mares with PPID may have hormonal abnormalities that result in abnormal lactation. It’s something that your veterinarian can test for, although probably not until the spring (research indicates that tests for Cushing’s Disease may not be accurate at the end of the year).If your horse is confirmed with Cushing’s Disease, the most commonly prescribed treatment is a drug called pergolide, which helps one of the horse’s own hormones, dopamine, do its job. It’s given orally, so it’s easy to administer. In fact, I’ve treated a couple of mares that have acted just like yours that stopped their mammary development when on the drug.