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Canine Alopecia: When Dog Shedding Is Actually Hair Loss

Canine alopecia is a symptom of several causes, including demodectic mange and ringworm.

Dogs who wear sweaters in the winter may shed a bit more, which is normal. By: funkblast

It’s that time of year when you take out your gloves and a woolly hat for the morning dog walk. Indeed, for some dogs, it’s also the time of year when they wear a coat for the first time since last winter. And for some people, it’s also the time when their dog decides the couch would look better upholstered in dog hair.

If there are blizzards (of fur) inside as well as out, then you might wonder what’s going on. You wouldn’t be the first person to ask the vet why there is so much fur.

For the vast majority, the answer is the dog is fine, but sitting in front of a heater and wearing a coat means that their luxurious thick winter pelt isn’t needed anymore. Instead, Mother Nature has the dog shed the extra fur.



However, not all shedding is innocent. Some dogs suffer from medical conditions that cause the coat to fall out, usually in patches. If the result is a bald patch or patches, this is known as alopecia.

Alopecia is a symptom that presents when the rate of hair loss is greater than that of regrowth. Put simply, the dog has a net loss of hair, a bit like trying to fill a leaky bucket when water runs out more quickly than you can fill it.

What Alopecia Looks Like

Alopecia is a fancy way of saying “baldness.” Depending on the cause, it can affect part or all of the body. But know it’s normal for a dog to have a lack of fur in the groin: If this sounds like your dog, it’s not alopecia — it’s normal.

Common places for alopecia to be present include:

  • The flanks
  • Around the eyes
  • The ear tips
  • The base of the tail
  • Various patches on the body

Some dogs can have temporary alopecia, such as the dog that suffers post-clipping baldness. People may be familiar with this as a baldness that follows the dog being clipped up for surgery. Instead of the fur regrowing as expected, a bald square persists for several months.

The explanation with these dogs is that they are seasonal hair growers. This means they have a spurt of hair growth at a certain time of year, but in between, their hair stops growing. All you have to do is be patient and wait for spring or the next hair growth cycle.

It’s also normal for dogs to have less fur in the groin area — this is not alopecia. By: Tony Alter

Alopecia Causes

Basically, what causes alopecia is anything that damages the hair follicle and stops it from growing a new hair. In our bucket analogy, this is like the faucet being damaged, so there’s no water to fill the bucket.


In the case of a dog, this could be parasites invading the hair follicle or excessive grease production plugging it. Here are some of the most common reasons:

  • Parasites: Such as the demodectic mange mites, which invade the hair follicle.
  • Fungal infections: Ringworm is a fungi that grows down the hair shafts, deep into the follicle, causing hair to fall out.
  • Bacterial infections: A heavy bacterial infection can cause spots (like acne in people) that eject the hair, leaving scar tissue and baldness.
  • Excessive grease production: Dogs suffering from seborrhea have a disturbance of the turnover of skin cells and grease production. When too much grease is produced, it clogs the hair follicles and prevents healthy hair growth.
  • Hormonal: Certain hormonal conditions, such as underactive thyroid glands, deprive the follicles of the hormonal stimulation needed to produce new hairs.
  • Inflammation: Scratching damages the hair shafts and causes inflammation. If the scratching is severe enough, the skin produces fibrous scar tissue which replaces active follicles.

When It’s Time for the Vet to Step In

How do you know when to seek veterinary attention?

Post-clipping or seasonal alopecia isn’t linked to soreness, inflammation or itchiness. In other words, the skin looks just fine; it’s just you can see skin because the fur is missing.

However, if the skin is reddened, inflamed, sore, ulcerated or sticky looking, then a vet checkup is in order. For these dogs, it’s likely there’s an underlying cause that needs treatment to stop further hair loss.

Another reason to visit the vet is if the dog is showing other symptoms or acting out of character. This could be something as simple as sleeping more (underactive thyroid glands) or drinking more (Cushing’s disease).

Watch this pup’s fur grow back after she experiences a range of ailments, including demodex mites:

Finding a Cause

Hair loss is a symptom rather than a diagnosis. To find the cause, the vet will look at the bigger picture, including things such as parasite control, itchiness and whether the dog is acting out of character.

From this, the vet builds up a working list of likely suspects. They’ll then start investigating the most likely problem first and work down the list until the answer is found. Tests that might need to be run include:

So if your dog is shedding heavily this winter, accept that you are doing a good job of keeping them warm. And if the dog develops bald patches, then they’ve stepped over into alopecia, and chances are they need to see the vet.


This pet health content was written by a veterinarian, Dr. Pippa Elliott, BVMS, MRCVS. It was last reviewed Dec. 1, 2017.