Abnormal Facial Sweating

Q. I have a Quarter Horse mare who sweats on the right side of her head mainly when she ships in a trailer or gets nervous, but also when she has been lying down. This problem has been ongoing since we purchased her, and now she has lost most of her hair starting at the center of her face and reaching all along the right side. She rides well but does show some resistance when turning left (I don’t know if this is related or just a problem with what I am doing). Do you have any suggestions of what the problem might be?

Chris Beaune, via e-mail

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A. Veterinarians occasionally see focal or patchy sweating in horses, and it is most common on the neck or shoulders but can also be seen on the head, withers, or girth area. There is a well-recognized condition called Horner’s syndrome, which in horses is characterized by sweatin