How do i tell if my dogs alergy is a yeast infection or a true allergy?

Question

my dog itches and scratches constantly benedryl doesnt control it. She has lost her hair in a couple spots and the skin has turned black.

Answer 1

Typically, dogs do not get yeast infections on their skin, for the most part they get yeast infections in their ears. Benadryl should not be given unless your dog has been examined by a vet in order to rule out other problems, and you should get dosing from your vet!

Most of the time with allergies, it starts on the feet, red irritated paw and the dogs just constantly l**k themselves raw, it then usually progresses to the groin and tummy. For a dog to scratch so much the hair is falling out, I would really be wary of parasites. There are a few parasites, some of which live in the skin and others that live on top and on the hair that can cause intensive scratching and bald patches, I would also worry about ringworm, however that usually starts in one spot and grows bigger leaving a bald, crusty lesion.

I would call your vet and have your dog examined as soon as possible, ensure that they check for everything from food allergies to parasites. And just to let you know, Benadryl is not a very effective product for dogs with allergies, most of the time a steroid and pain medication is prescribed,

Answer 2

The only way is to have her allergy tested.  It gives a very effective diagnosis these days but it's not cheap.