That looks like a tick-hole to me (not a techincal term). Zoey takes frontline, but at the end of the month during a particularly bad tick season last fall, she was bitten by a tick. We removed the tick, and for a long time after (I'm talking weeks) there was a mark that looked like that one. Zoey's 'cousin' BooBoo was also bitten by tick and he also had a similar mark. I know that ticks normally bite the head not the leg, but that definately looks like an insect bite of some sort to me (hence the blood spot in the middle from the bite and it's probably raised from swelling).