Question: dog is missing hair on tail?
Answer: Worms and Other Icky Things. Worms (especially tapeworms) coming out of the anal area can create irritation, causing your dog to lick and bite at the area, as well as around the tail. ... Flea allergy is also a common cause of hair loss on the tail. In fact, the tail and groin are preferred sites for fleas, said Osborne.