[Lacy's Mom]

I actually use grapefruit seed extract (GSE) in my aviary all the time. I use it to disinfect baby feeding syringes, add to water to combat bacteria, add it to the baby's bath water, add it to handfeeding formulas to reduce bacteria problems in the crop. I also add a few drops to the dog's water if they have diarrhea that lasts more than 24 hours. It is very similar in properties (antibacterial, antifungal) to tea tree oil, but can be ingested safely. It is very concentrated and must be diluted prior to using. I think it might be safer (when diluted) than the tea tree oil, especially since you have an open sore.

If you think it might be mange I would also give him something to boost his immune system like Vitamin C and echinacea. Also make sure he is protected against fleas because it could be a reaction to flea bites.