Alopecia (hair loss) - causes of it

Alopecia is the common term used to describe hair loss but also includes a failure of the hair in the first place. Alopecia is usually a sign of an underlying disorder (e.g. underactive thyroid, cushings disease), which must be diagnosed accurately by a veterinarian in order for effective treatment to begin. Another cause of alopecia can be stress, exposure to a chemical irritant or seasonal pollen, if no medical reason can be found for the hair loss have a look around the house and garden for chemicals/pollens your pet maybe exposed to or any situations that could be causing stress to your pet. There are many natural products available to help your pet deal with stress.


Dermatitis is a skin condition that could cause skin irritation and alopecia in dogs. Allergic, contact or atopic dermatitis could occur if a dog has sensitivity to antibiotics, pollens, plants (e.g. poison ivy), fleas, food additives or intolerances, chemicals, perfume/deodorisers.

Another type of dermatitis is called acral lick dermatitis, which occurs when a dog licks itself obsessively due to anxiety, boredom, or stress, rather than skin irritation. Acral lick dermatitis is a psychological condition that can result in hair loss. Seek advice from an experienced dog trainer on how to help your pet overcome fear, anxiety, stress or boredom (refer to the trainers page).


External parasites commonly cause alopecia in dogs. Fleas, ticks, lice and mites can all cause intense itching and scratching which leads to hair loss. Parasites can also physically damage the hair follicles, and allergic reactions to the parasites can cause hair loss as well. A dog fed garlic and brewer’ yeast in their daily food makes a pet an undesirable host for parasites due to an odour their skin emits.

Fungal and Bacterial Infections

Fungal infections of the skin (dermatophytosis) can cause partial to complete alopecia with scaling and with or without associated redness. Some fungal infections are transmittable to people which means that they have the potential to cause skin lesions in people . Ringworm is a fungal infection that affects dogs, cats and people (always wash your hands after handling a pet with ringworm). Symptoms of a fungal infection include hair loss, scaliness, crusty areas, pustules, vesicles, some itching. Below are two examples of ringworm on paws.

Yeast is a fungus that is always present on pets, when the immune system becomes over burdened, the yeast will multiply in the hair follicles and throughout the body leading to the animal becoming itchy and even odorous (smelly ears indicated a yeast infection in the ears). Anti-fungals like coconut oil and diluted apple cider vinegar can be successful in treating fungal infections.

Bacterial infections, especially those caused by Staphylococcal species – can cause alopecia with redness, crusting and circular patterns of hair loss.

Hypothyroidism (Underactive Thyroid)

The most common hormonal disease affecting dogs, and occurs when the thyroid gland ceases to function properly. The dog then begins to suffer a hormonal imbalance which interrupts the hair growth cycle resulting in hair loss. Symptoms of a hypothyroidism include hair loss, dry and brittle hair, seborrhea, bacterial and yeast infections; lethargy, weight gain, slow heart rate and changes in skin pigmentation may occur. Treatment includes a daily hormonal supplement medication and/or supplementation with iodine rich foods.

Cushing’s Disease

A serious chronic illness caused by a hormonal imbalance that occurs when the adrenal glands no longer function properly. The adrenal glands play a huge role in the stress response and are involved in producing over 50 hormones (including cortisol and aldosterone) that drive almost every bodily function, many of which are essential for life and regulate normal body functions.

Cushing’s disease occurs when the adrenal glands produce too much cortisol and aldosterone. Cortisols have an effect on the metabolism of sugar, fat, and protein and are partially responsible for the reaction known as fight or flight response during stressful periods. Aldosterone regulates salt and potassium in the body.

Hair loss and thinning of the skin are common symptoms in dogs with Cushing’s disease. The hair loss usually starts over the areas of wear such as the elbows and progresses to the flanks and abdomen until eventually only the head and extremities have hair. The skin may also become thin and be easily damaged and slow to heal.

Treatment for cushing’s disease can involve surgery and/or medication. Dogs that have been on corticosteroids for a long time may develop a reversible form of Cushing’s disease that can be cured by tapering off the steroids. Food that can restore adrenal health include: coconut, avocado, vegetables, fatty fish, chicken and turkey, nuts, seeds (pumpkin, chia and flax), kelp, seaweed and bone broth.

Reactions to Medication or Injections

A reaction to medication can lead to hair loss, e.g. chemotherapeutic treatments for cancer commonly cause alopecia. Hair loss that occurs at injection sites is usually caused by an inflammatory reaction to the substance that was injected. Rabies vaccines have been known to cause patchy hair loss around the injection site 2 to 3 months after been given.


Lazarus, Pat, 1999, Keep Your Dog Health the Natural Way, The Ballantine Publishing Group, New York, USA

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