Hair Loss (Alopecia) in Dogs: Why Is My Dog Losing Hair?

Depending on your dog’s breed, you can find yourself knee-deep in hair twice a year. I can tell you that even our Rotties, who but no stretch of the imagination are fluffy dogs, can drop an enormous amount of undercoat. You would never expect it–they don’t look like they’re wearing much. But when Jasmine was shaved for her surgeries, it was clearly visible she had about an inch of tightly packed undercoat.

That is normal shedding and not what we’re talking about.

You and your family members too put away your winter coat when the spring comes. And, depending on how tight of a household you run, you might find garments all over the floors also.

Hair Loss (Alopecia) in Dogs: Why Is My Dog Losing Hair?

The difference between shedding and hair loss isn’t where you do find the hair but where you don’t find it–on your dog.

Finding bald spots on your dog means there is a problem. Your dog can have just bald patches or losing hair all over.

There were three reasons I have found bald patches on my own dogs.

Jasmine was hypothyroid and prone to skin infections. We kept things under control fairly well but she had a hot spot twice and folliculitis (an infection of hair follicles) twice. She lost the most hair with that one and for a while, it looked it was never going to grow back. The chunks of coat that came off her still had bits of skin attached to them.

JD had a bald spot which we thought was a result of the game of chicken he played with a tree. The tree didn’t blink and JD ended up with a boo-boo on his nose. Even though it looked healed, the area remained hairless. It turned out he got ringworm infection.

The most mysterious hair loss was Jasmine dime-sized spot on her flank. It wasn’t ringworm. It wasn’t anything else either. Our of all things, her veterinarian decided to try melatonin and the fur grew back almost immediately.

Infections or parasites

Four out of five cases of hair loss in my dogs were due to an infection. Skin infection in dogs, however, aren’t usually the primary problem. Most of the time they come secondary to allergies, trauma, immune dysfunction … anything that messes with the skin’s natural defenses. Bacterial skin infections in dogs are mostly bacteria that are normally present on the skin growing out of control–not contagious. Ringworm is a fungal infection that is contagious.

Allergies can lead to bacterial infections in two ways. Either from self-trauma such as scratching and biting, or disruption of the skin’s protective layer due to inflammation. Or both.

Demodectic mange, while a parasitic skin disease, also doesn’t happen in a dog with a healthy immune system. These things live in the hair follicles and cause no harm unless their numbers get out of hand, such as with an immature or compromised immune system. Demodex is not itchy.

Sarcoptic mange (scabies), however, is highly contagious, meaning that most dogs’ immune system has never been equipped to ward these off. Sarcoptes is extremely itchy and tends to occur specifically on the edges of ears and lateral elbows.

Hormonal disorders

Poor thyroid function, excessive levels of steroids (Cushing’s disease), high estrogen, low testosterone can be the cause behind symmetrical hair loss.

Too little thyroid hormone and too much cortisol can also be the grounds for secondary infections.

Other causes

Other potential causes include immune disorders, hereditary or congenital issues, nutritional deficiencies, or systemic issues.

Your dog’s skin and coat are a reflection of their health. Any changes in coat quality or hair loss is a red flag telling you there is a problem to deal with. When my dog starts losing hair, I not only look at the immediate cause such as an infection, but I want to see what is going on systematically. Why isn’t the immune system tackling this? Is it too agitated? Is it too weak? Why?

Related articles:
Dandruff/Flaky Skin in Dogs

Further reading:
8 Causes of Hair Loss in Dogs

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Jana Rade edited by Dr. Joanna Paul BSc BVSc

I am a graphic designer, dog health advocate, writer, and author. Jasmine, the Rottweiler of my life, was the largest female from her litter. We thought we were getting a healthy dog. Getting a puppy from a backyard breeder was our first mistake. Countless veterinary visits without a diagnosis or useful treatment later, I realized that I had to take Jasmine's health care in my own hands. I learned the hard way that merely seeing a vet is not always enough. There is more to finding a good vet than finding the closest clinic down the street. And, sadly, there is more to advocating for your dog's health than visiting a veterinarian. It should be enough, but it often is not. With Jasmine, it took five years to get a diagnosis. Unfortunately, other problems had snowballed for that in the meantime. Jasmine's health challenges became a crash course in understanding dog health issues and how to go about getting a proper diagnosis and treatment. I had to learn, and I had to learn fast. Helping others through my challenges and experience has become my mission and Jasmine's legacy. I now try to help people how to recognize and understand signs of illness in their dogs, how to work with their veterinarian, and when to seek a second opinion. My goal is to save others the steep curve of having to learn things the hard way as I did. That is the mission behind my blog and behind my writing. That is why I wrote Symptoms to Watch for in Your Dog, which has turned out being an award-winning guide to dog owners. What I'm trying to share encompasses 20 years of experience. Dr. Joanna Paul BSc BVSc is our wonderful sponsor and has been kind to edit and fact-check my important articles.

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