My 5 year old thoroughbred mare has a lump about the size of a big grape right near her right mandible, under the jaw, very close to the gland. It is semi-hard, free floating it seems, and she gets annoyed when I poke at it. I don't see how she could have contracted strangles since she never leaves the barn, but who knows. Are there any other suggestions for what it may be? She coughed a little while riding her today, but she never coughs in the stall or outside, she's eating, drinking, and being a pain in the butt just as usual.