Why is my Dog Losing Hair? The Causes of Alopecia

Alopecia, or hair loss in dogs, is caused by diseases and conditions that affect the health of your dog’s coat, from the skin down to the hair follicles. Diagnosing the direct cause of hair loss is key for veterinarians to treat alopecia. In fact, there are over fifty known conditions that can cause hair loss in dogs, so many vets have their work cut out for them.

The most common causes of alopecia fall into three categories:

1. Parasitic Causes of Alopecia

Infection, allergy or reaction to parasites can bring on hair loss in dogs. Common parasitic causes of alopecia include:

• Mites - the Demodex mite is a  microscopic mite that lives in the hair follicles. Exposure to this mite, combined with a weak immune system, causes red mange, also known as puppy mange, which can induce hair loss. A Sarcoptes mite infection or exposure to other less common mites can also cause different types of  mange and hair loss.
• Fleas - dogs that are sensitive to flea bites or who have flea allergy dermatitis can experience hair loss due to excess itching and irritation.

2. Allergic Causes of Alopecia

Allergic reactions have been known to affect dog hair in certain cases. Allergies that have been linked to alopecia include:

• Food Allergies - some food allergies will cause itching, redness, and hair loss.
• Atopy - allergies to particles in the air that dogs inhale such as dust, mold, or pollen can induce alopecia.
• Medicine - allergic reactions to medications or injections can cause hair loss.
• In some cases, allergies to or issues with the fit of a collar or bedding can cause Alopecia

3. Endocrine and Hormonal Causes of Alopecia

Dog’s with endocrine disorders and hormonal imbalances can experience hair loss. Such disease include:

• Cushing’s Disease - this condition stems an increase in corticosteroids caused by overproduction in the adrenal glands, or an imbalance due to prolonged therapy using corticosteroids.
• Hypothyroidism - the most common hormonal disease that affects dogs, hypothyroidism’s lower production of hormones can cause hair loss.

Other Causes of Alopecia

Other causes of alopecia include bacterial and fungal infections that affect the skin or hair follicles. Ringworms, or the onset of kerion infection from ringworms, are the most common fungal cause that can lead to alopecia.

Nursing or pregnant dogs can develop a type of alopecia called “blowing their coat,” which develops from nutritional deficiency or stress.

Stress, trauma, nutritional deficiencies, and hereditary causes can also lead to hair loss. Some breeds have a genetic predisposition to certain types of alopecia; they include doberman pinschers, boxers, bulldogs, airedale terriers, pomeranians, chow chows, miniature poodles, samoyeds, and siberian huskies.

Pet owners who see signs of hair loss should contact their vet. Some of the underlying causes of alopecia may be symptoms of severe illness that could be treated with early intervention.

The Symptoms of Alopecia in Dogs

Alopecia is an abnormal type of hair loss caused by a disease or condition. Unlike seasonal shedding, this type of hair loss can appear in patterns, bald patches, and over specific areas of the head, body, legs, and tail. The symptoms and severity of alopecia will vary from case to case depending on the underlying cause of the hair loss.

The most common symptoms of alopecia include:

Noticeable hair loss

While some dogs develop thinning or brittle hair with age, alopecia affects the coat due to an underlying cause that requires treatment. Pet owners may notice bald patches or larger areas of complete or partial hair loss on their dogs. The hair loss may be gradual or sudden. In some cases, the hair may grow back partially and then fall out again. The hair loss may look symmetrical or random, or appear in completely bald patches. Hair loss can affect one specific area of the body, such as the base of the tail or the haunches, or appear all over.

Skin changes

While some dogs only exhibit hair loss with alopecia, others may also experience changes in the skin. Check for scaly skin, changes in skin color, inflammation, bites, redness, lesions, and hot spots. You may also find changes in the skin’s texture, such as thickened, oily, or thinner skin. Darkened skin is a symptom of one type of alopecia known as Alopecia X, or black skin disease.

Behavior changes

Some dogs display symptoms such as scratching, biting, licking, or chewing their skin with alopecia. Dog’s with hormonal or endocrine disorders may also experience lethargy and other signs of illness.

Signs of alopecia can be connected to more serious illnesses, such as Cushing’s disease. If you notice hair loss on your pet’s coat, make sure to visit your veterinarian to diagnose the underlying cause.