Hair Today, Gone Tomorrow: Causes Of Hair Loss In Dogs

It can be disturbing to discover patches of hair loss on your dog's previously flawless coat. In most cases, the hair loss is more than just a cosmetic issue. Many of the causes of hair loss can be controlled or cured, and failure to do so can lead to bigger problems. Learn about some of the more common causes of hair loss in dogs and what your veterinarian can do to restore your dog's coat to its luxurious glory.


When dogs react to allergens, itchy skin and subsequent hair loss as a result of scratching are the typical symptoms. Allergies can be incited by any of the following triggers:

  • Environmental allergens, such as molds, dust mites and pollens
  • Contact irritants, such as carpet cleaners or lawn chemicals
  • Food ingredients, particularly protein or carbohydrate sources
  • Flea saliva, which results in a specific allergy called flea allergy dermatitis

Triggering allergens can be identified through allergy testing, feeding trials and the use of flea preventative products. In the case of environmental triggers, treatment may include allergy injection therapy or symptomatic treatment with medications during seasonal flare-ups.

Alopecia X

Alopecia is the general term used to indicate hair loss. While many causes of alopecia can be identified, the X in alopecia X means unknown cause. Alopecia X goes by a number of other names, including coat funk, black skin disease and castration-responsive alopecia. It is usually seen in breeds that originally hailed from cold climates. Such breeds include the following:

  • Alaskan malamute
  • American Eskimo
  • Chow chow
  • Norwegian elkhound
  • Pomeranian

Alopecia X typically presents in young adult dogs as hair loss, and the skin is not usually itchy. Some unneutered dogs with alopecia X regrow the hair once they are spayed or neutered. Another treatment method is the administration of oral melatonin. Growth hormones and other drugs have been used to treat alopecia X, but since the condition is purely cosmetic, the potential risks for side effects outweigh the benefit of using such medications.

Color Mutant Alopecia

Color mutant alopecia is a genetic skin disorder that typically occurs in dogs with blue or fawn coats. The condition is sometimes called blue Doberman syndrome because it is a common affliction of Doberman pinschers with blue coats. Other breeds can develop the patchy bald spots, including the following:

  • Chow chow
  • Chihuahua
  • Dachshund
  • Great Dane
  • Greyhound
  • Italian greyhound
  • Poodle
  • Whippet
  • Yorkshire terrier

The symptoms of color mutant alopecia first present within the first three years of the dog's life and include areas of hair loss wherever the dog's coat is blue or fawn in color. The bald areas can be scaly, itchy and become infected. There is no cure for color mutant alopecia, and the condition is managed through bathing with medicated shampoo to keep the skin and hair follicles clean and prevent infection.

Cushing's Disease

Cushing's disease, which is also known as hyperadrenocorticism, is a hormonal condition that results from high cortisol levels in the bloodstream. One of the symptoms of Cushing's disease is hair loss on the torso. Other symptoms of Cushing's disease in dogs include excessive thirst and urination, a pot-bellied appearance and an increase in appetite. Cushing's disease, which most commonly affects middle aged and older dogs, is diagnosed through laboratory blood and urine tests. Cushing's disease must be closely monitored and treated. Treatment plans include various drug options, surgery and, in some cases, radiation therapy.


Hypothyroidism is another hormonal disease that can cause hair loss in dogs, as well as weight gain and lethargy. Hypothyroidism occurs as a result of thyroid hormone deficiency, and it is typically occurs in middle aged and older dogs. The condition is diagnosed by performing thyroid hormone profile blood tests, and it can be managed with lifelong oral medication and periodic monitoring.


Hair loss can occur as the result of a skin infection. Skin infections may be caused by any of the following:

  • Bacteria, such as in the case of pyoderma
  • Yeast, such as in the case of malassesia
  • Fungus, such as in the case of ringworm

Diagnosis of a skin infection is based on the symptoms and on the results of various tests, including fungal and bacterial cultures. Depending on the type of infection, treatment may include antibiotics, antifungal medications, medicated baths and cortisone to relieve itchiness, if necessary. Hair regrows in most cases once the infection is cleared up.


External parasites can result in hair loss which may be caused by scratching, either due to crawling fleas that make the dog itchy or by parasites that burrow under the skin and crowd hair follicles. External parasites that can cause hair loss include the following:

  • Fleas
  • Demodectic mange mites
  • Sarcoptic mange mites

Mange mites can be identified through diagnostic skin scraping tests and are treated with medicated dips or ivermectin treatments. Fleas can be easily controlled with the use of a flea preventative product from your veterinarian.

If you notice any hair loss on your dog, schedule an appointment with your veterinarian for an evaluation. You should also have your dog examined if you observe signs of itchiness, skin irritation or flaky skin so that subsequent hair loss may be averted. Contact a center like Apple Valley Animal Hospital for more information.