Hair on a dog grows in cycles, and it takes about four months for the average dog to grow a coat, although it is slightly different depending on the breeds.
Most dogs shed their hair at least once a year. The main influence on dog shedding is the seasonal length of daylight.
In spring, longer periods of daylight activate the shedding of a dog’s hair. In fall, as the daylight hours grow shorter, many dogs shed their haircoat again.
Dogs living indoors and exposing to artificial light may shed and grow their haircoat all year round.
What is Canine Alopecia?
Canine alopecia is a medical condition in which there is excessive hair loss in dogs, and which is unrelated to the normal hair shedding and growing cycle as mentioned above.
Alopecia in dogs can be partial and localized (restricted to one or two places in the body), or it can be complete and generalized.
So… what causes hair loss in dogs? Read on to find out!
Hormonal Diseases That Cause Hair Loss in Dogs
Several hormonal diseases in dogs cause canine alopecia. They include:
Cushing’s Disease
Canine Cushing’s disease (hyperadrenocorticism) is a condition caused by a long-term exposure to high levels of corticosteroids. It may be either due to medication or over-production of the hormones because of, in most cases, malfunctioning of the pituitary gland.
Cushing’s disease in dogs causes symmetric hair loss over the body. Other symptoms associated with this disease is a sagging pot belly, frequent urination, and appetite gain.
Hypothyrodism
Hypothyroidism in dogs is the most common cause of dog hair loss. The hair loss is bilateral and symmetrical without itching. The hair coat is usually thin and hair falls out easily.
Other symptoms include weight gain (without appetite increase), intolerance of cold weather and exercise, and lethargy.
Diabetes Mellitus
Diabetes in dogs is a common immune disorder in dogs. Obese dogs and un-spayed female dogs are more prone to the disease.
In addition to hair loss, dogs with diabetes show four classic symptoms: increased drinking, increased frequency of urination, increased appetite, and weight loss.
Growth Hormone-Responsive Alopecia
This type of hair loss in dogs is the result of a deficiency of adrenal hormones. The hair loss caused by this condition is symmetrical and bilateral. The condition affects mainly males and it begins around puberty.
It is more common in certain breeds, including Pomeranians, Chow Chows, Keeshonds, Samoyeds, Boxers, and Poodles.
Estrogen Deficiency Alopecia
This type of dog hair loss occurs in older spayed female dogs. Typical symptom is thinning hair coat initially around the vulva which later spreads over the whole body. The skin is soft and smooth.
Other Diseases That Cause Hair Loss in Dogs
There are quite a few other diseases that cause canine alopecia. Some common ones include:
Ringworm
Canine ringworm is a fungal infection and the classic symptom is a spreading circle of hair loss in the center with a red ring at the periphery.
But some cases of ringworm have atypical symptoms with irregular areas of hair loss (not in a circle) spreading across the face or nose, with scaling and crusting.
Demodectic Mange
Demodectic mange is a skin disease caused by a microscopic mite called Demodex canis. It usually occurs in puppies and young adults with hair loss around the eyelids, lips, and mouth corners (sometimes also on the legs or trunk).
Seborrhea
Canine seborrhea with hair loss usually occurs secondary to other skin problems such as demodectic mange, scabies, atopy, etc.
Seasonal Flank Alopecia
The exact cause of this problem is unclear. A dog with seasonal flank alopecia loses hair in the flank area on a seasonal basis. Different dogs seem to choose different seasons to lose their hair (fall and spring are popular). When the season changes the hair generally grows back.
Breeds susceptible to this problem include the Boxers, Airedales, and English bulldogs.
Nasal Solar Dermatitis
Also commonly known as “Collie nose”, this skin problem is an autoimmune problem. It causes hair loss at the junction of the nose and muzzle, and can cause scaling and ulceration.
It usually affects dogs with noses that are lightly-pigmented, such as the Collies, Shelties, and similar breeds.
Callus
Calluses are hairless thickened pads of skin (usually on the elbows) which result from chronic pressure, caused by lying on hard surfaces. Large breed dogs are more prone to calluses.
Injection Site Alopecia
This type of hair loss occurs at a site where the dog has been injected with a medication or vaccine.
Zinc-Responsive Dermatosis
Zinc deficiency can results in crusty and scaly red skin with hair loss over the face, the nose, elbows, and hocks.
Breeds more susceptible to this problems are the Arctic or Northern breeds such as the Huskies and Malamutes.
Treatment of Hair Loss in Dogs
Treatment of dog hair loss of course depends on the underlying cause.
If your dog suddenly loses his hair, try to look for other accompanying symptoms. This can help your vet to diagnose more speedily and accurately.
Supplements such as fatty acids (e.g. salmon oil) and vitamins (especially A, C, and E) are beneficial to the skin and haircoat. Adding these supplements to your dog’s diet may help prevent some skin problems that may result in hair loss.
Coconut oil is another oil that is good for dog skin and hair.