Alopecia is one of the most common skin disorders in dogs. Alopecia on dogs causes the animal to have partial or complete hair loss, but it also refers to deficiencies in a dog’s coat or a failure to grow hair at all. It can affect a dog’s skin, endocrine system, lymphatic system, and immune system, in addition to his coat.

Alopecia can affect dogs of all ages, breeds, and genders, and the condition can be either gradual or acute. Typically, alopecia is a sign of an underlying canine medical issue which must be identified and diagnosed before the Alopecia can be resolved. For instance, if a dog has hair loss and is also scratching excessively, the cause of the itching should be investigated first.

While it’s normal for dogs to shed and sometimes have patchy coats in between seasons, serious hair loss is usually a sign of alopecia.

Causes of Alopecia in Dogs

Because alopecia is such a broad disorder, there are many potential causes. Alopecia and hair loss can be congenita (meaning a dog is born with the condition) or it can be acquired.

Alopecia occurs when the growth of hair follicles becomes disrupted. If there are several missing patches of hair, it could be related to inflammation of the hair follicle. If the hair loss is a larger, more widespread area, it may be because of a specific disease or infection.

Acquired alopecia can be caused by any disease that affects hair follicles. Some diseases may completely destroy the hair follicle or shaft, while others interfere with hair growth. Acquired hair loss can be inflammatory in some cases and cause discomfort.

Dogs of any age, sex, or breed can develop alopecia, although certain breeds are more prone to the disorder. For example, Chihuahuas, Dachshunds, Greyhounds, Whippets, Doberman Pinschers, and certain Arctic breeds are at a higher risk for developing bald spots. In most cases, hereditary alopecia is harmless.

Congenital Hair Loss

Congenital alopecia does not necessarily have to be hereditary, although it can have a genetic basis. It is caused by the absence of the normal development of hair follicles. If alopecia is congenital, it may be noticeable at birth, or it might not become apparent until later, as widespread hair loss occurs as the dog ages.

Allergies

Hair loss can also be due to allergies. Dogs can be allergic to a variety of substances, but the most common sources are flea bites, insect bites, stings, pollens, grasses, chemicals, foods, and medications. These can cause allergic reactions in dogs, such as itching, hives, and rashes, which prompts dogs to chew and scratch at their skin, damaging their coats.

Bacterial Infections

Canine bacterial infections, such as bacterial folliculitis or infections caused by Staphylococcal (staph), can cause alopecia in dogs. This condition is usually associated with redness and crusting, along with hair loss. If alopecia is the result of a bacterial infection, it should be treated with antibiotics prescribed by a vet.

Fungal Infections

Fungal infections (or dermatophytosis), like canine ringworm, can cause partial to complete alopecia. With ringworm, hair loss appears in circular patterns, and it’s often associated with lesions, inflammation, redness, and crusting of the skin. Some fungal infections are zoonotic, which means it can be passed from a dog to a human, or from one species of animal to another. Fungal infections sometimes clear up on their own, but it’s usually best to seek treatment with an antifungal shampoo, ointment, or other medication.

Hormonal Imbalances

There are many different endocrine, or hormonal disorders that can contribute to alopecia in dogs. Cushing’s disease, Addison’s disease, hypothyroidism, hyperthyroidism, hyperestrogenism (in females), and hypoandrogenism can all result in some form of alopecia. Each of these disorders may have other, more serious, symptoms, and should be diagnosed and treated by a vet.

Mange

One of the most common causes of alopecia is mange, which occurs as the result of an overpopulation of mites (most notably, the Demodex mite). Mange is classified as an inflammatory disease, but symptoms (other than hair loss), can depend on the type of mite the dog has. The condition can lead to extreme hair loss and crusting of the skin if left untreated.

Parasites

External parasites, like ticks, lice, mites, fleas on dogs are another common cause of alopecia. These irritants can cause itching and scratching, which leads to hair loss. They can also physically damage a dog’s hair follicles or cause an allergic reaction, which can also result in hair loss.

Stress

Dogs who suffer from canine anxiety, depression, psychological disorders, or have been previously abused are more likely to develop alopecia. These conditions can lead to nervous behavior like chewing, licking, and excessive grooming, which can cause localized balding and hair loss.

Temporary Hair Loss

Temporary hair loss can be the result of stress, but it can also occur during dog pregnancy or lactation. Illness, fever, injury, pressure sores, or excessive grooming can cause temporary alopecia on dogs as well. In some cases, something as simple as friction—from a poorly fitted collar—can result in bald spots.

Alopecia can also occur on its own and sometimes has no particular cause at all.

Symptoms of Alopecia in Dogs

Alopecia is extremely noticeable; the symptoms may present themselves in a variety of ways, but generally speaking, alopecia is characterized by hair loss or thinning of the hair. The signs of alopecia in dogs can vary depending on the underlying causes or diseases.

Hair loss can be gradual and worsen slowly over time, it can also be acute, resulting in sudden bald patches and other related symptoms. It can be localized and isolated, and have no other clinical signs associated with it, or become more generalized, and spread as it progresses.

In some situations, the skin may appear normal, without any redness or inflammation, and the dog may have no reaction to the hair loss. Other times, alopecia can present as bald spots accompanied by crusting, irritation, and scaling around the area.

With congenital, or hereditary, alopecia, the hair loss can be symmetric, occurring on both sides of the body, or be located in just one area. This type of alopecia is usually not inflammatory.

Besides hair loss, alopecia is frequently associated with other clinical symptoms. Dogs with alopecia will often itch, scratch, and chew due to irritation. Often the skin affected by the hair loss will also become red, darkened, irritated, or inflamed. Sometimes, the skin can become oily. In extreme cases, dogs can develop blisters or sores in the affected areas.

Some causes of alopecia may lead to the development of secondary skin diseases, such as infection or fluid discharge. These can lead to foul odors, and crusty, thickened or raised skin.

The symptoms a dog develops due to alopecia typically depend on its underlying causes. If you suspect that your dog has alopecia, especially if it is acute alopecia, you should take him to the vet in order to establish a specific diagnosis.

Diagnosis of Alopecia in Dogs

For your vet to make the most accurate diagnosis, you will need to give them a thorough history of your dog’s health. They will also need to perform a physical examination.

Typically, your vet will need to know the duration and progression of the hair loss, whether or not your dog has been scratching, if you’ve noticed any evidence of an infection (and related symptoms like lethargy, loss of appetite in your dog, etc.), and information about your dog’s general health.

The physical portion of the appointment will include an examination of your dog’s skin. Your vet will note the pattern and distribution of the hair loss. Different patterns of hair loss can indicate different causes.

• Multiple areas of hair loss may be due to a fungus infection like ringworm. This usually appears with scaling and reddened skin.
• Alopecia that presents as symmetrical is often congenital or a result of a hormonal imbalance. This may be because of low thyroid levels, excessive levels of estrogen, or lower levels of testosterone.
• Patchy and generalized hair loss can happen if mange is the cause of alopecia. Fungal or Bacterial infections in dogs may also cause this type of hair loss.

Your vet will also check for signs of secondary infections, parasites, and injuries, and then analyze your dog’s hair to determine if they are breaking off or shedding directly from the hair follicle.

If necessary, your vet may order diagnostic laboratory tests to determine the cause of the hair loss. These might include skin smears and cultures to determine if a bacterial, fungal, or yeast infection is the cause. Your vet may also order blood testing and urine samples if they suspect a hormonal imbalance is to blame. If those tests are inconclusive, your vet may move onto a skin biopsy to confirm other types of inflammatory or cancerous causes.

Treatment of Alopecia in Dogs

In general, alopecia is treated with topical shampoos and antibiotic therapies. Because it is usually a symptom of a larger, underlying medical problem, the cause needs to be accurately diagnosed in order for your vet to prescribe an effective treatment.

If your dog is diagnosed with a parasitic issue that is causing the hair loss, your vet will likely prescribe topical medication to treat the external parasites. Once the parasites have been killed and eradicated, your dog’s hair should start growing back as normal, although it may take weeks or months for his hair to grow back completely. Your vet may also recommend flea and tick prevention medications to keep this type of alopecia from happening again. If you live in areas that are typically infested with parasites, you should regularly use flea and tick repellants to keep your dog from becoming infected.

Alopecia that is caused by hormonal imbalances is treated based on the underlying disorder. Sometimes spaying and neutering your dog will rectify the condition, other times your pet will need to take hormone replacement medications for the rest of his life.

If it’s been determined that your dog’s alopecia is a result of an allergic reaction, your vet may try and narrow down the aggravator so you can eliminate it from your pet’s environment. Your vet may also prescribe medicated shampoos, anti-inflammatory medications, antihistamines, or corticosteroid therapy to alleviate the condition.

Medicated shampoos are also effective at treating a number of infections, including mange. Your vet may recommend oral or topical antibiotics as part of an infectious treatment plan.

It may take some time to narrow down the exact cause of alopecia, so in the meantime, your vet may prescribe topical medication to manage or reduce your dog’s discomfort and itching that’s related to the hair loss. These treatments can include prescription antibiotics, antifungals, or steroids in the form of ointments, creams, lotions, and shampoos.

If alopecia is a result of your dog excessively grooming, chewing, and licking, he may have to wear a cone or Elizabethan collar until he’s able to break the habit and stop the behavior.

Prevention

Alopecia cannot always be prevented, however, there are several things you can do to keep your dog’s coat healthy, barring all other underlying medical conditions. Providing a safe, clean, and stress-free environment along with a nutritious diet will keep your dog healthy overall.

Keeping a close eye on your dog’s general health, and regularly grooming him will help you recognize any skin or coat issues as soon as they arise. You should also schedule an annual check-up and examination with your vet; these will usually include blood and urine tests, which can help your vet identify and treat or prevent medical issues that may lead to alopecia.

Alopecia is not necessarily a serious medical condition, although it normally points to an underlying issue. Work with your vet to ensure your dog retains a healthy and shiny coat.

Sources:

“Hair Loss in Dogs.” PetMD, www.petmd.com/dog/conditions/skin/c_dg_alopecia.

petMD. “5 Common Causes of Hair Loss in Dogs.” PetMD, 20 July 2017, www.petmd.com/dog/slideshows/general-health/common-causes-of-hair-loss-in-dogs.

Clark, Mike. “Alopecia Or Hair Loss In Dogs: Symptoms, Causes, And Treatments.” Dogtime, 18 Mar. 2019, www.dogtime.com/dog-health/54391-alopecia-hair-loss-dogs-symptoms-causes-treatments.