What can be the cause of an armpit sore? My horse has a sore in his left armpit since last summer—it’s not from a girth (had off all winter) and I think it might be a bed sore.

And it could also be caused by being chubby .
Hey Jodi, this could be caused by many things e.g. Bug bites , nipping , allergies and more. I would suggest just using some quick relief pain but if you think your horse is distressed still then see a vet
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