Dog Lip Tumor Picture Serious Diabetic Dog Question?

Serious diabetic dog question? - dog lip tumor picture

My dog, Charley) (photo left, is diabetic. it is good, but has an open fly just below the mouth developed, almost on the lips. He is also blind, and thought he had encountered on something and cut her lip. However, there has been a week and still has a red strawberry. I just started to the cream of the human anti-biotic, but I wonder whether he needs to see the vet? In addition, the red spot could be cancer?

with a special diabetes ordinary things of another dog, and medicine for the eyes can not afford to spend a lot absouletly the essentials. So if you visit the vet can be avoided, I need it. Thank you.