Why Is the Hair on My Dog's Tail Falling Out?

By Ann Compton

Problems from allergies to a serious illness can cause a dog's tail hair to fall out. Observe your dog's behavior and overall health if you notice hair loss and consult your veterinarian to determine whether the cause requires treatment.

Parasites or Allergies

Your dog may chew his tail if his hind end is irritated. Parasites or allergies can cause this behavior. If you suspect fleas, check your dog's coat for flea dirt, which appears as small black dots on his skin, and apply a flea treatment. Some dogs have seasonal allergies from pollen or grass that cause tail chewing. If your dog is chewing so persistently that he is losing tail hair, see your vet for allergy testing. He may prescribe allergy medication or a change in diet.

Thyroid Issues

Hair loss on the tail can occur when a dog's thyroid gland does not function properly. Breeds such as golden retrievers, Labrador retrievers, dachshunds, rottweilers, cocker spaniels, Irish setters and boxers are more prone to hypothyroidism than others. This illness can be diagnosed in any breed but is more prevalent in medium to large breeds over 4 years old. It is usually found in dogs with weakened immune systems.

In addition to hair loss on the tail, the dog's coat may become thin and dull, and his skin dry. Weight gain and lethargy may also occur. See your vet to diagnose hypothyroidism. Medication is usually prescribed to alleviate the symptoms.

Types of Mange

Mange is caused by mites and can manifest in hair loss on the tail or around the dog's tail. A dog with mange will be itchy and chewing the affected area.

  • Demodectic mange is most often found in puppies or dogs with weak immune systems. You may see scabs or sores on your dog's skin where the hair has been lost. A puppy with mange may recover on his own, but an adult dog should be tested by a vet for underlying conditions. Treatment can include a veterinary dip to kill the mites that cause the condition.
  • Sarcoptic mange is caused by a specific mite and is a more serious form of the disease. It can spread to a dog's entire body and cause severe itching and skin irritation. This mange is contagious to other animals. Your vet will take a skin scraping or do a microscopic examination to diagnose this condition and treat by using a chemical dip to kill the mites.

Cushing's Disease

Hair loss on a dog's tail can be the first sign of Cushing's disease. A dog with this illness may also exhibit increased thirst and appetite. He may develop a distended stomach and pant more frequently. Cushing's generally develops in dogs after middle age and can be found in all breeds. A vet will usually perform blood tests and an ultrasound to confirm the diagnosis. Cushing's sometimes involves a tumor and if one is present, surgery may be required. Otherwise, dogs are usually treated with oral medication.