Alopecia is a medical term that refers to baldness or hair loss on areas that normally are hairy. There are many reasons a dog can develop alopecia, including allergies, skin infections, parasites including fleas or mange mites, overgrooming, lack of protein in the diet, and genetics. Depending on the cause, the alopecia might be a temporary condition that can be treated, or it might be a permanent condition. Luckily, although it can be unsightly, alopecia is generally not part of a life-threatening condition, and your dog can usually lead a normal, happy life even without all of its fur.
While any dog can develop alopecia that stems from external factors such as mange, skin infections, or behavioral issues, certain breeds are more prone to inherited types of alopecia. Dachshunds, Chihuahuas, standard poodles, and Bernese mountain dogs are just a few of the breeds prone to genetic types of alopecia.
What Is Alopecia?
Alopecia is the medical term for hair loss or baldness. There are many different types of alopecia that affect dogs. With most types of alopecia, the dog's fur loss is temporary and hair growth resumes once the root cause is treated. However, inherited forms of alopecia are sometimes permanent or recurring conditions.
Depending on the cause of the alopecia, the dog might lose most of the fur on its body, but more often, alopecia leads to partial hair loss in the form of localized bald spots, symmetrical hair loss on one or both sides of the body, or fur that looks thin and moth-eaten.
Alopecia can affect any part of your dog's body, but most often appears on the ears, the top of the head, the belly, or the flanks.
Symptoms of Alopecia in Dogs
The most obvious symptom of alopecia is hair loss, but other symptoms can accompany this condition, depending on the cause.
Alopecia that's caused by a hereditary or hormonal issue often has no symptoms beyond the changes to the dog's coat. However, when the hair loss stems from an infestation of parasites, such as fleas or mange mites, a fungal or bacterial infection in the skin, such as ringworm, or allergies, your dog will often be itchy and scratch excessively.
Damaged skin tends to accompany the itchy forms of alopecia. You'll see dandruff or flakiness on your dog's skin, and might note reddened or darkened skin, as well. If the inflammation is severe, there might be crusty or weeping spots on the skin. Usually, your dog will lick, scratch, or rub at the irritated areas in an effort to gain relief from the discomfort.
Causes of Alopecia
Alopecia can occur for a number of reasons, but causes are typically lumped into two categories: congenital or acquired. Congenital alopecia means the dog is born with hair follicles that do not develop normally, usually due to genetics. Symptoms of these types of alopecia can appear when the dog is still a puppy or later in young adulthood.
Acquired alopecia means the dog was born with a normal coat and normal hair follicles, but now has areas of baldness or hair loss due to damage to the hair follicles, issues with the hair shaft itself, or a slowdown in the normal hair-growth cycle.
Many causes of alopecia have specific names, while others are simply symptoms of another illness or condition. Some named types of alopecia include:
- Alopecia Areata: Focal areas of hair loss are classic with this type of alopecia. This is a rare auto-immune disease that typically doesn't have any inflammation. It is usually seen on the head and neck.
- Follicular Dysplasia: This type of alopecia affects specific breeds and causes a thin coat that is often described as being moth-eaten in appearance. Color dilution alopecia and follicular lipidosis are specific forms of follicular dysplasia and are due to a genetic cause.
- Post-Injection Alopecia: After some types of injections, especially the rabies vaccine or shots of steroids, some dogs develop alopecia at the injection site. Post-injection alopecia is due to the inflammation these injections can cause in the skin.
- Post-Clipping Alopecia: Sometimes when a dog's fur is shaved, the fur does not grow back normally in the clipped area. The cause of this type of alopecia is unknown.
- Pattern Baldness: This hair loss has an unknown cause, but is likely hereditary. It leads to progressive hair loss, mostly over the dog's neck, thighs, and belly. It also often causes darkening of the skin in the affected areas.
- Traction Alopecia: When a dog's hair is styled too tightly with barrettes, rubber bands, or other fashion accessories, the hair follicles can become damaged enough to drop their hairs.
- Pinnal Alopecia: Isolated to the ear flaps, pinnal alopecia is a congenital form of alopecia that causes hair loss on the ears.
Alopecia can also occur due to parasites such as mites or fleas, environmental or food allergies, bacterial or fungal infections, hormonal issues such as low thyroid hormone (hypothyroidism) or high cortisol (Cushing's disease), some tumors, topical medications, and even seasonal fluctuations.
Certain breeds of dogs are predisposed to developing various types of congenital alopecia. Breeds that are commonly affected by different types of alopecia include:
- Alaskan Malamutes (post-clipping alopecia)
- American Water Spaniels (pattern baldness)
- Bichon Frises (post-injection alopecia)
- Boston Terriers (pinnal alopecia and pattern baldness)
- Boxers (pattern baldness)
- Chesapeake Bay Retrievers (follicular dysplasia)
- Chihuahuas (pinnal alopecia, follicular dysplasia, and pattern baldness)
- Chow Chows (post-clipping alopecia and follicular dysplasia)
- Curly-Coated Retrievers (follicular dysplasia)
- Dachshunds (pinnal alopecia, follicular dysplasia, and pattern baldness)
- Doberman Pinschers (follicular dysplasia)
- German Shepherds (post-clipping alopecia)
- German Shorthaired Pointers (follicular dysplasia)
- German Wirehaired Pointers (follicular dysplasia)
- Great Danes (follicular dysplasia)
- Greyhounds (pattern baldness)
- Irish Setters (follicular dysplasia)
- Irish Water Spaniels (follicular dysplasia)
- Italian Greyhounds (pinnal alopecia, follicular dysplasia, and pattern baldness)
- Keeshonds (post-clipping alopecia)
- Labrador Retrievers (post-clipping alopecia)
- Manchester Terriers (pattern baldness)
- Miniature Pinschers (follicular dysplasia)
- Newfoundlands (follicular dysplasia)
- Poodles (follicular dysplasia)
- Portuguese Water Dogs (pattern baldness and follicular dysplasia)
- Rottweilers (follicular dysplasia)
- Salukis (follicular dysplasia)
- Samoyeds (post-clipping alopecia)
- Schipperkes (follicular dysplasia)
- Shetland Sheepdogs (follicular dysplasia)
- Shih Tzus (post-injection alopecia)
- Siberian Huskies (post-clipping alopecia and follicular dysplasia)
- Silky Terriers (post-injection alopecia)
- Whippets (pinnal alopecia, follicular dysplasia, and pattern baldness)
- Yorkshire Terriers (post-injection alopecia and follicular dysplasia)
Diagnosing Alopecia in Dogs
If your dog develops bald spots or thinning of its coat, one of your veterinarian's first questions is likely to be whether or not you have observed signs of itchiness, such as scratching excessively. Itchiness typically indicates an inflammatory cause of alopecia or a response to food or environmental allergies. In these cases, your vet will look for signs of skin infections from yeast, ringworm, or bacteria and also examine the dog for signs of pest infestations, including fleas or mange mites.
Along with the physical examination, your vet might order skin scrapings or biopsies of the affected areas for microscopic examination, which can reveal typical changes associated with inflammation. Blood tests can sometimes reveal an increase in certain types of white blood cells that indicate allergies.
If your dog is not itchy, the veterinarian will likely order blood tests to check for abnormalities with the dog's thyroid, as well as blood tests that give an impression of the dog's overall health. The vet will also carry out a full physical examination, considering the symmetry of the bald spots, their location, changes to the underlying skin, and the appearance of the remaining hairs.
If your veterinarian is unable to decisively diagnose the cause of the alopecia, they might refer you to a veterinary dermatologist. However, it is not uncommon for alopecia to be simply diagnosed as idiopathic, meaning the cause is unknown.
The treatment for alopecia in dogs will vary based on the underlying reason for the hair loss. If the problem is due to a skin infection or irritation, the treatment will involve topical or oral forms of anti-parasitics, antibiotics, antifungals, or anti-inflammatory medications.
If the alopecia is due to thyroid or adrenal disorders, treatment to relieve or reverse the hormonal imbalance will usually also result in renewed hair growth. If allergies are the source of the problem, then removing the trigger—often it's a food—as well as giving the dog antihistamine medications can bring relief from the itching that caused the dog to scratch away at its fur.
Unfortunately, many forms of congenital alopecia do not have effective treatments, other than keeping the dog's skin moisturized to help avoid dryness or flakiness.
Prognosis for Dogs With Alopecia
Although many forms of alopecia cannot be cured or treated, they do not shorten a dog's life or affect the quality of that life. For the most part, alopecia is a cosmetic issue that can be unsightly but won't prevent your pet from leading a happy and otherwise healthy life.
How to Prevent Alopecia
Some types of alopecia are preventable while others are out of a dog owner's control. Using parasite control and making sure any hair accessories are not applied too tightly are the best ways to prevent these avoidable types of alopecia. Other types of alopecia that are due to a genetic or auto-immune cause are not preventable but may be lessened for future generations with selective breeding.
Is Alopecia Contagious to Humans?
Hair loss itself is not contagious, but ringworm, which is one cause of alopecia, is contagious to humans and other pets in the home, as are many types of mange mites. If your dog's alopecia is due to one of these causes, you'll need to take precautions against the spread of infection by washing the dog's bedding, keeping the infected dog separated from other pets in the home, and taking care to wash your hands thoroughly after petting your dog or applying medications to its skin.
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Hair Loss (Alopecia) in Dogs. Merck Veterinary Manual.
Focal, Non-Inflammatory Alopecia: A Diagnostic Treatment Challenge. DVM360.
Diagnosing and Treating Alopecia in Dogs. Veterinary Practice News.