What does this look like? Ringworm, Spider Bite, Other?

Not ringworm -- that's a fungus and the hair just plain falls out in an area (and it almost NEVER starts on the belly -- typically ear tips, toe tips, tip of tail)

Looks like a bite of some sort -- you might want to give benedryl just in case but watch and see if it develops a hard swelling.  It could be a sting as well or just a small breakout.

Thanks Callie.  I knew the hair was supposed to fall out if it was ringworm, but I didn't know just *how soon* it would fall out...so I wondered if I had just caught it in the beginning stages or something.  That stuff scares me. 

I had it on my mind already because my sister had been talking about someone she knew with it the other day, and so then when I saw a weird, red, circular shape on Beau, I freaked and took him to the vet.  I figured he must have picked it up from one of the cats he has been around recently, or the cows living in our backyard.  (Okay, on the other side of our backyard fence, but still...)  But the vet told me it was probably just a spider bite.  Phew!  I stil wanted a second opinion though, juuuust in case.  Did I mention I don't like ringworm? 

By the way, kinda OT, but...my vet told me that cows don't carry ringworm.  I have always thought they did?