Two weeks ago, I noticed this exact same sore on Remi's snout. No real swelling occured, and I never noticed a side effect other than what you see here. It healed up pretty quick. Today, I find this on Lulu. It doesn't see to be too sore based on her reaction when cleaning it. Looks like a snake bite, which is a little worrisome cause it means the snake is likely in our garage or basement. Maybe a big wolf spider? I never seen this before, but I figure one of you guys has the answer.