Seeing your dog lose hair on the hind legs can be alarming, especially if the skin looks irritated, flaky, or unusually smooth.
Hair loss in this area is commonly linked to allergies, parasites, hormonal conditions, over-licking, or skin infections — and the exact cause often depends on whether the hair loss is patchy, symmetrical, or accompanied by itching.
We outline the common causes of hair loss on a dog’s hind legs, what you can do, and when to seek veterinary help.
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Dog Losing Hair on Hind Legs — Why It Happens
Dogs lose hair on their hind legs when the skin becomes irritated or inflamed due to allergies, parasites, infections, hormonal imbalances, or excessive licking or chewing. Some conditions create symmetrical hair loss, while others affect small patches or cause widespread thinning.
Allergies and parasites are among the most common culprits, but issues like thyroid disease or Cushing’s disease can also lead to slow, progressive hair loss on the back legs.
Because the hind legs are a high-friction area affected by licking, scratching, environmental exposure, and systemic health changes, hair loss here can provide important clues about your dog’s overall health.
Understanding the pattern and severity of the hair loss helps determine the underlying cause.
Dog Losing Hair on Hind Legs: Common Causes
Environmental Allergies
Environmental allergies — such as reactions to pollen, grass, mold, dust mites, or seasonal triggers — are one of the top reasons dogs lose hair on their hind legs.
Allergies cause skin inflammation, which makes dogs bite, chew, or scratch the backs of their legs, eventually breaking the hair follicles and creating bald patches.
Because many dogs lie down with their hind legs tucked under or stretched behind them, allergens easily collect on the skin.
Over time, repeated scratching causes irritation, redness, and hair loss concentrated on the thighs, hocks, or backs of the legs.
Dogs with environmental allergies often lick their paws or rub their faces as well, offering additional clues.
Read more: Dog losing hair in patches and scabs (Why it happens)
Fleas or Flea Allergy Dermatitis
Flea allergy dermatitis is extremely common and causes intense itching even from a single flea bite.
Dogs with flea allergies often develop bald patches near the tail base, lower back, and hind legs — classic locations where fleas like to feed.
Mild cases may show only thinning hair, while more severe reactions cause scabs, redness, crusting, and constant biting or chewing.
Because many dogs swallow fleas while grooming, you may not see fleas on the coat, even during an active infestation. This condition tends to worsen rapidly without proper flea prevention.
Food Allergies (Consistent Year-Round Itching)
Food allergies can cause chronic skin inflammation that leads to hair loss on the hind legs. Unlike environmental allergies, which flare seasonally, food allergies cause symptoms consistently throughout the year.
Common triggers include:
• chicken
• beef
• dairy
• wheat
• soy
• eggs
Hair loss occurs because itching leads to over-licking or chewing on the thighs and flanks.
Some dogs develop smooth bald patches with mild redness, while others show bumps or thickened skin. If your dog also has ear infections or digestive issues, food allergies become even more likely.
Mange
Mange can cause patchy or widespread hair loss on the hind legs, depending on the parasite involved.
Demodectic mange (Demodex)
• Causes smooth circular bald patches
• Often affects young dogs or dogs with weak immune systems
• Hair loss may appear on the legs, face, and trunk
Sarcoptic mange (Scabies)
• Causes intense itching
• Leads to fast hair loss on hind legs, belly, and elbows
• Highly contagious
Both types create redness, scaling, and discomfort, and dogs often chew or bite the affected areas, worsening the hair loss. Without treatment, mange can spread quickly.
Hormonal Disorders
Hormonal imbalances are a major reason for hair loss that appears identical on both hind legs. These conditions typically cause slow, progressive thinning rather than scabs or irritation.
Two of the most common include:
Hypothyroidism
An underactive thyroid slows down metabolism, affecting the skin and coat. Signs include:
• Symmetrical hair thinning on the hind legs and trunk
• Dry, flaky skin
• Weight gain
• Low energy
Cushing’s Disease
Excess cortisol causes:
• Thinning hair on hind legs and belly.
• A pot-bellied appearance
• Increased thirst and hunger.
• Skin that bruises easily.
With hormonal diseases, the skin usually isn’t itchy, but hair fails to regrow after shedding or trimming. The symmetrical pattern is a key diagnostic clue.
Bacterial or Yeast Infections
Skin infections can develop anywhere but commonly affect the hind legs due to licking, scratching, or moisture trapped in the fur.
Dogs may lose hair in patches or experience scabbing, redness, odor, or thickened skin.
Yeast infections create greasy, darkened skin and a musty smell, while bacterial infections may ooze or form crusts.
These conditions often occur secondary to allergies or irritation, so treating the infection alone may not stop the underlying problem.
Over-Licking From Pain or Anxiety
Over-licking can cause noticeable hair loss on the hind legs, especially on the lower thighs and hocks. Dogs may lick because of:
• joint pain (arthritis, hip issues)
• anxiety
• boredom
• compulsive behaviors
When licking becomes habitual, the hair becomes thin, the skin darkens, and bald patches form. Chronic licking often indicates that the dog is self-soothing due to stress or discomfort.
Read more: Dog Losing Hair in Patches on Back (Underlying causes explained)
What to Do If Your Dog Is Losing Hair on Their Hind Legs
Begin by examining the area closely for redness, bumps, fleas, scabs, or signs of irritation.
If your dog seems itchy, chewing the area, or acting uncomfortable, consider switching to a strict flea prevention plan first — even if you don’t see fleas. Flea allergy dermatitis is extremely common and often overlooked.
If allergies may be involved, avoid new treats and consider simplifying your dog’s diet. Bathing with a gentle, hypoallergenic shampoo can soothe irritated skin and reduce allergens.
Try to limit licking by redirecting your dog with toys or enrichment activities, but avoid using physical punishment or harsh deterrents.
Ensure your dog isn’t exposed to potential irritants such as scented detergents, chemical lawn treatments, or rough bedding. Keeping the skin clean and dry helps prevent infections from developing.
When to Call or Visit Your Vet
Contact your vet if:
• hair loss is rapidly spreading
• the skin looks inflamed, red, scabby, or infected
• your dog is in pain or constantly licking the area
• you suspect mange or observe intense itching
• the hair loss appears symmetrical
• your dog shows signs of weight gain, lethargy, or excessive thirst
Because hind-leg hair loss can indicate allergies, parasites, infections, or hormonal issues, a professional exam helps identify the exact cause and ensures proper treatment.
Read more: Dog shedding excessively (What’s causing it?)
Key Takeaway
Hair loss on a dog’s hind legs is usually caused by allergies, parasites, infections, hormonal disorders, or excessive licking. The pattern of hair loss — patchy, symmetrical, itchy, or smooth — helps narrow down the root cause.
Early treatment prevents complications like infections, discomfort, and spreading hair loss. With the right approach, most dogs recover fully and experience healthy regrowth.