Question: I have a wonderful Paint/Thoroughbred cross mare who’s healthy and full of life. But there is the issue of her dirty udder! Savannah develops an oily, black crust primarily between her teats that builds up over a couple of days. We generally try to soften it up with a little Dawn soap whenever we rinse her after a ride. Fortunately, she doesn’t seem to mind and allows us to rub the mess away. But we do have some questions that I hope you can answer for us because in a barn populated primarily with geldings, no one seems to know for sure: What causes this accumulation? How much buildup is normal? Should we be washing it away on a regular basis or is it best to just leave it?
Answer: You are right, mares do have their own unique hygiene issues, and this is among the most common: The skin around a mare’s mammary glands produces a sebaceous exudate similar to the smegma seen on geldings. This substance protects the delicate skin of the teats from the rigors of nursing foals as well as from chafing as the two sides of the udder rub together when the mare walks. But, as you already know, waxy or sticky buildup can accumulate in this space.
Healthy skin in this area is hard to describe, but in general it will feel like it has a slightly waxy coating. Normal skin will not be dry, flaky, reddened or irritated. Some mares may have thick, smelly chunks of greasy debris in this area, but it usually takes months or even years for the exudates to build up to this level.
It does sound like Savannah is an overachiever in this regard—it is not typical for this buildup to accumulate as quickly as you describe. Individuals vary, however, so it may be normal for her. Another possibility is that over-zealous washing is stimulating the overproduction of the exudates. This coating is important to protect the skin, and the body will step up production if it senses that there isn’t enough.
Nonetheless, you don’t want to leave a thick or chunky layer of exudate between any mare’s teats because the material can harbor bacteria and capture dirt, which makes the accumulation abrasive and can lead to more severe skin irritations.
Whenever the buildup on the udder becomes heavy, a gentle washing and drying is in order. Dawn dish soap will work fine for most—use only a tiny dab on a wet sponge to prevent the skin from becoming too dry. A gentler option would be a commercial sheath-cleaning solution sold for geldings. Whatever you use, be sure to rinse well and pat dry gently with a clean towel or paper towels. Most mares need this kind of care just two to four times per year. A small number of mares need no such cleansing, and a few need it more often.
For Savannah, or any mare, I would suggest that if her udder needs to be cleaned more than once a month, it is time to check in with your veterinarian. If the skin is intact and pain-free, then a special trip isn’t needed—just raise the question the next time your veterinarian comes out for something else. But if there is any redness, swelling or pain, then make an appointment specifically for this issue. Your veterinarian may prescribe a medicated shampoo, suggest a change in the frequency of washes or give you a topical medication to apply after the washes.
Melinda Freckleton, DVM
Melinda Freckleton, DVM, owner of Firestar Equine Veterinary Service, is a graduate of Cornell University’s College of Veterinary Medicine with years of experience in both equine practice and small animal medicine. She enjoys riding and competing in dressage and taking care of her dogs, cats and horses on her small farm.
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