Canine flank alopecia is sometimes known as seasonal alopecia because it is a light responsive seasonal disorder. It causes partial or total hair loss on the dog’s flank and back area. Lack of exposure to the sunlight in the months with shorter days seems to be connected to this disorder. It usually begins in late fall into early spring and lasts up to six months. Sometimes this condition recurs yearly, but not in all cases. About 20% of the time is will occur only once in the dog’s life. This disorder is also called cyclic follicular dysplasia, and it is a non-inflammatory condition.

Canine flank alopecia is a syndrome usually occurring in the fall through spring months. It has no known cause and produces hair loss in the flank and back of the dog.

There are two different types of seasonal flank alopecia. Both types are non-inflammatory, which produce no itching or scratching.

There are no known causes of seasonal flank alopecia. Seasonal changes in melatonin and prolactin occur in dogs and other mammals. Lack of exposure to the sunlight to the pineal gland could be responsible. The pineal gland is responsible for producing melatonin, which modulates sleep patterns in seasonal cycles. A lack of sunlight may cause the hair to fall out of some dogs on a seasonal basis. There does not appear to be a sex predilection and it may be hereditary. Some breeds are more susceptible such as Boxers (50% of all cases), Bulldogs, Schnauzers, Labradors, Scottish terriers, Akitas, Airedales, and Doberman pinschers. This condition is more common in areas in that have dark winters. Indoor dogs are most susceptible due to the lack of being outdoors during daylight hours.

Most dogs show signs between November and March each year. If your dog is showing symptoms, he will need to be examined by a veterinarian. Clinical signs and symptoms will be noted, and pigmented bald spots will be identified. Your dog’s breed will be considered, as well as the time of year. Skin biopsies may be necessary, which may detect follicular atrophy (white bumps), comedones (canine acne), epidermal thickness, and hyperpigmentation of the skin. Other diseases and disorders such as Cushing’s disease, thyroid disease, parasites, mites, and bacteria will be ruled out by appropriate testing. The average age of the diagnosis of seasonal flank alopecia is 4 years old.

Exposure to sunlight during the months of September through March dramatically lessened the incidence of flank alopecia. Find a way to providing an opportunity for your dog to spend more time outdoors, especially in the fall and winter. This will greatly improve his chances of not developing seasonal flank alopecia.

Melatonin is a hormone that regulates the body of the dog’s daily rhythm. It can help to thicken and regrow the dog’s fur. Melatonin oral supplements or injections may be administered or recommended. Melatonin implants under the skin are available in some countries. Melatonin oral supplements are effective approximately 50% of the time. Follow your veterinarian’s advice on the proper dosage and frequency. Generally, melatonin will be given daily for two or three months until complete hair growth occurs. Restarting melatonin yearly four to six weeks before the anticipated onset of hair loss may prevent recurrence the following year.

There is a good, but unpredictable prognosis with most dogs regarding the growing back of their hair. However, some dogs skip a year of hair growth and some may not ever regain all of their hair. Sometimes the hair may even grow back in a different color and texture. Seasonal flank alopecia is a cosmetic disorder and does not affect the health or quality of life of the dog.