sores on spine

he has a sore on his spine I have been treating with neosporin and peroxide.  He is a stray and kind wild.  It's not the first sore on his back but it dosen't look like a cat fight sore.  It is round.  he stays in the garage at night and is usually in the garage all day.  i don't know what it could be caused by.  Can't take him to vet can't catch for that.

[Kimberly Coyner, D.V.M., DACVD]

Potential causes for the sore could be overgrooming due to flea allergies or other allergies, a bacterial skin infection, a fungal (ringworm) skin infection, and trauma. I recommend getting him used to eating and sleeping in a pet crate, so that he can be taken to a veterinarian for examination, diagnosis and treatment, as well as routine health care such as vaccinations, deworming, neutering, and testing for feline leukemia and feline AIDs. For now you can continue the Neosporin, but I would stop the peroxide, as it is irritating. If you have any Advantage or Frontline for your other cats' flea control, then use it on your garage cat too; do not use any over the counter flea control products, as they can be very toxic to cats.
Good luck,
Kimberly Coyner DVM DACVD
www.dermvetvegas.com