My baby, Poe, (born 8/28/2009) has a sudden lump on his chin. I noticed it 1, maybe 2 days ago now. It is firm, and warm to the touch. There are some brown flecks as you can see, but I don't think they're acne as they don't produce any oil when I try to gently express it. There's no wound under the fur. Just very, very tight skin.
He DOES have bad breath, but he always has had since the day he was born. No additional lost teeth or change in color to gums. He doesn't necessarily like it being pressed on, but doesn't vocalize; just pulls his face away. There's no change in his behavior or eating. He gets along with my other cats and I haven't WITNESSED him fighting. Doesn't mean it hasn't happened, though. No history of food allergies. (I have a cat who does, on occasion, get a small swelling in her chin when she eats the wrong kind of canned food, and it looks nothing like her reaction.)
They're on a grain-free, soy-free food. It's not the best, but it isn't crap.
I gave him 5mg of prednisone (corticosteroid I use when the food allergy cat's chin flares up) 24 hours ago with no improvement.
How can I tell if this is cyst, tumor, or abscess? Again, it's warm, and pretty dang firm. Wouldn't an abscess feel squishy?