My Cocker Spaniel Scratches His Mouth Until He Bleeds. He Has Little Holes On The Outside Of His Mouth. What Is Wrong With Him?

Following are the possibilities of different reasons of itching in your dog.

1. Contact allergy
2. Allergy to pollens
3. Food allergies
   
4. Chiggers: Sever itching on ears, mouth and between toes.
5. Insect/fly bite
6. Fungal and bacterial infections
7. Ticks and lice
   
8. seborrhea
   

Visit to vet is necessary. Meanwhile you can give benadryl which is anti allergy. You can apply fatty acids (marine oil or evening primrose oil) and also bathe in cool water by adding baking soda, Epsom salt and colloidal oatmeal. But ideally vet can do better.