From: Andrea
Hi - I thoroughly enjoy your newsletter and will be sending my "support" shortly. Thanks for providing this wonderful service.
I did look through your archives and found a helpful article on the subject of barren mares "lactating." But I am still confused about my mare. She is approximately 17 years old and I have owned her for the last 10 years. In those ten years she has never been pregnant. I don't know if she was every bred prior to my owning her. I have noticed occasional light leaking from her udders when I am grooming or cleaning in between, and never gave it much thought. But today, I noticed that one teat was quite swollen, and when I massage it fluid streamed out. There was no heat, and my mare stopped eating her grain while I manipulated the udder and appeared to be relieved by the "milking", rather than in any pain. Could this still be mastitis without heat or pain? Could it be itchy? The fluid was clear and with no foul odor. I will heed your advice about not milking as it will produce more. But I am concerned by this sudden onset and the fact that there was definite swelling. Overall, she is in good health. your thoughts and comments would be appreciated. Thank you
Andrea
Your vet needs to take a look at your mare, just in case something else is causing this - it's always best to rule out possibilities such as Equine Viral Arteritis, but yes, she could have mastitis. The condition isn't limited to in-foal or nursing mares. However, if the condition comes and goes without any treatment, it may be something else - clearing up a case of mastitis generally requires some human (manual or medical) intervention. This does not sound like mastitis to me, though, because in my experience, mastitis is uncomfortable or painful, and the swollen udder is just ONE aspect of mastitis. If your mare's udder isn't warmer than usual, if she shows no pain when it's handled, and if she doesn't have a fever or seem uncomfortable or unhappy, then I'd be looking for another answer. It's easier to tell with mares that are actually producing milk, because there's usually a dramatic change in the milk on the affected side of the udder, and you can compare the lumpy or discoloured milk from that side to the normal milk from the other side. Mares with mastitis CAN produce very thin, watery milk from the affected side of the udder, but don't assume that your mare has mastitis just because she is producing a watery fluid.
The udder area is tricky because if there's fluid accumulation somewhere along the horse's underbelly, including the udder and the area just in front of the udder, it could be a reaction to a local problem (a blocked teat, a bit of old (or new) scar tissue somewhere, a bruise, etc.) or it could be unrelated to the udder itself, and originate higher in the body. Liquid DOES tend to migrate to low spots, after all.
It may be of use to you AND your vet if you'll keep a journal and note factors such as weather, diet, exercise, and medications - sometimes, after a few months of recording daily observations, a pattern will become obvious. If no pattern emerges, that's also useful information. ;-)
If it proves to be the case that there's some sort of lump interfering with normal lymphatic drainage, your veterinarian may be able to use ultrasound or cold laser therapy. Both of these are non-invasive, and neither one causes pain. Meanwhile, ask your vet about mastitis and lymphedema - and don't be surprised if no one comes up with anything conclusive.
One of my own mares shows a similar condition periodically, and the vets haven't been able to come up with a definitive diagnosis. She's done this off and on for the last fourteen years - she's 28 now. The veterinary concensus is that the condition isn't harmful, doesn't seem to bother the mare, and really isn't a problem except for the anxious owner. There's no heat and no pain reaction when the udder and surrounding area are handled, and the mare's temperature is always normal. When I kept a journal, the only consistent pattern I could find was that the swelling episodes generally coincided with her strongest heats, usually between late June and mid-September. I theorized that there might be a hormonal cause of the swelling, that it might be connected with a hormonal "spike" associated with her estrus cycle. My vets agreed that it was possible, but... nobody could say that this was definitely the case.
I've known several extremely obese mares that showed very strongly swollen udders until they were treated with a thyroid supplement and brought down to a more normal weight, at which point this sort of swelling became smaller, more infrequent, and much less of a problem. They were put on the reducing diet and supplement because their vet was concerened about laminitis - nothing to do with their udders - but the effect on their udders was obvious. Here again, I wouldn't discount the possibility of an hormonal connection - probably between the thyroid supplement (or the need for same) and the mares' production of prolactin. Ask your vet - s/he will probably know much more about this than I do.
Part of the problem, as you'll see when you begin keeping a journal, is that there are always so many variables. For instance, although the summer/strong estrus connection seemed very plausible to me, there was no way to be sure. The seasonal connection was clear, but as for the cause... There are so many other things that go on during the summer months - there are more insects, there are more fly-bites, there are flowering grasses and trees, pollens everywhere... and of course fly-spray and sweat must be taken into account, as well.
Good luck!
Jessica
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