Q: My 27-year-old Thoroughbred mare has facial swelling on and off. Lately, it has been more on than off but it has been occurring for the past eight months. In the beginning I thought maybe she was eating something out in the field, but I have tried four different fields and it doesn’t seem to make a difference. Generally, the swelling is concentrated around her chin but it has also been on her lips and by her ears. Part of me wonders if she has some sort of lymphoma. What else could it be?  —Heather Mercedo; Easton, Maryland

A: This is something that you really want to get your veterinarian involved with right away. Unexplained swelling that waxes and wanes can be an important sign of infection or systemic illness, and you want to get to the cause of it promptly.

Your veterinarian will want to do a full physical examination. Among the things she will look for are signs of swelling in other areas of the horse’s body, especially the legs, chest and belly (and the sheath if this was a gelding). She will listen for heart or lung sound changes, look for signs of diarrhea and examine the horse’s head and mouth.

I assume your mare is not having trouble raising her head because you did not mention that, but your veterinarian will also make sure her neck is working well.

If nothing definitive is found, it is very likely that simple blood work will help with further clues. A CBC (complete0 blood count) can help suggest whether the horse’s immune system is fighting infection or under other stresses, and a blood chemistry panel can help find liver or kidney failure or other systemic problems. You will not often get a specific diagnosis with these tests, but they are an important starting point for the eventual diagnosis.

I share your concern about lym-phoma0 or other cancers, but there are many other possibilities, including tooth root infections or oral abscesses. Or it could be some other, less common manifestation of a variety of other diseases. This is one of those cases where you’re better off knowing now, rather than taking a “wait and see” approach.

Melinda Freckleton, DVM
Firestar Veterinary Service, LLC
Catlett, Virginia