Alopecia (Hair loss) in Dogs
Your veterinarian will obtain a thorough medical history. Unlike most organ systems in the body, the skin can be directly observed. Therefore, what you have seen is very valuable in establishing a diagnosis. The breed, age, and sex of your animal may provide a clue. Expect to be asked about the age of your pet at the onset of the symptoms, the duration and severity of the symptoms, the degree of itching, medications previously used, and pattern of hair loss.
Your veterinarian will perform a thorough physical exam and skin exam. Particular attention will be paid to the pattern of hair loss and the distribution of the lesions. The appearance of the skin in the areas of alopecia will also be examined carefully.
Skin scrapings are commonly done to look for mites and other skin parasites. These scrapings are examined under a microscope.
Fungal cultures are often done to rule out dermatophytes (ringworm). Hair is plucked from the edge of the lesion and then is placed on a special culture media that turns from yellow to red in the presence of dermatophytes.
A trichogram may be done to characterize the alopecia. Hair grows in a cycle with a new hair being formed in the hair follicle to replace the hair that is mature and ready to be shed. Looking at hair under a microscope may tell the veterinarian if hairs are developing normally and may show broken hairs which would indicate a self-induced alopecia.
A hypoallergenic food trial or testing for allergen may be done to rule out allergy if the alopecia is related to pruritus.
A skin biopsy can be very helpful in diagnosing the cause of alopecia. The procedure may be done under general or local anesthesia. One or more small pieces of skin are taken from a skin lesion and submitted to a veterinary pathologist for examination. It is important for your veterinarian to send the sample to a pathologist with some expertise in dermatology. Even if the biopsy does not give a specific diagnosis, it may help to establish a path to diagnosis. For example, the results may indicate an allergic process, a hormonal process, or a bacterial process.
Blood tests for hypothyroidism, hyperadrenocorticism (Cushing’s disease), or another type of hormonal disease may be done.
The only way to successfully treat alopecia in dogs is to identify and treat the underlying cause. There are no symptomatic treatments.
If the alopecia is associated with pruritus, symptomatic treatments such as antihistamines, antipruritic shampoos, fatty acid supplements or corticosteroids may be temporarily helpful.
If alopecia is associated with pyoderma, antibiotics may help temporarily. Remember that pyoderma is nearly always secondary to another problem, so the underlying cause must still be found for long-term success.
Brushing dead and matted hair out of the coat may help to relieve symptoms that lead to alopecia.
Follow-up Care for Dogs with Hair Loss
Since there are so many different causes of alopecia, follow-up by the owner and communication with the veterinarian is critical. Administer all medications as instructed. Keep your dog’s coat clean and properly groomed. Observe closely for fleas. Flea infestation always makes alopecia worse.
Alopecia is the complete or partial lack of hair in any area of the skin where hair would normally be found. In dogs, it may be caused by self-trauma, hair follicle diseases or the failure of hair to grow after normal loss.