When a dog begins losing hair on the back end — around the hips, tail base, thighs, or lower back — it can be worrying, especially when the skin looks irritated, flaky, or swollen.
We outline the common reasons why a dog may lose hair on the back end, what you can do, and when to seek veterinary help.
Dog Losing Hair on Back End — Why It Happens
A dog losing hair on the back end is usually experiencing allergies, parasites, skin infections, hormonal disorders, or irritation caused by licking, scratching, or inflammation.
The back end — especially the tail base and hindquarters — is one of the most common locations for hair loss because it’s where fleas concentrate, allergies flare, and glands can become irritated. Dogs may chew, lick, or rub the area until hair thins or bald patches develop.
Sometimes the cause is mild, but other times back-end hair loss signals underlying medical issues such as hypothyroidism or chronic skin disease.
Dog Losing Hair on Back End: Common Causes
Flea Allergy Dermatitis (FAD)
Flea allergy dermatitis is the number one cause of hair loss near the tail base and lower back.
Even a single flea bite can trigger an intense allergic reaction. Dogs scratch, chew, and bite the back end aggressively, causing hair to fall out.
Typical signs include:
• Bald patches near the tail.
• Red bumps or scabs.
• Constant scratching or chewing.
• Flea dirt or actual fleas.
Dogs with flea allergies often show hair loss specifically on the rump, hips, and tail base. Without flea prevention, flare-ups return quickly.
Read more: Dog Losing Hair Around Eyes and Mouth (Causes explained)
Environmental or Food Allergies
Allergies frequently cause hair loss on the rear end, especially around the thighs and tail area.
Environmental allergens — like pollen, mold, grass, or dust mites — often cause hind-end itching. Food allergies can also cause itchiness and skin inflammation, particularly near the tail or back legs.
You may also notice:
• Ear infections.
• Licking paws.
• Red skin.
• Seasonal flare-ups.
When allergies are the cause, scratching leads to hair thinning, redness, and irritation.
Hypothyroidism (Low Thyroid Hormone)
Hypothyroidism is a hormonal condition that commonly causes symmetrical hair loss on the back end.
Dogs with this condition may have:
• Thinning fur on the back, tail, or thighs.
• Dry, flaky skin.
• Weight gain.
• Lethargy.
• Intolerance to cold.
The classic sign is “rat tail” — thinning hair or baldness along the tail. Because thyroid hormones regulate skin and coat, low levels cause hair to stop growing.
Hypothyroidism requires lifelong treatment but responds well to medication.
Mites
Mites can irritate the skin and cause intense itching or hair loss on the back end.
Demodex mites often cause patchy hair loss with mild itching, while sarcoptic mange causes severe itching and thick crusts. Hair loss may begin around the hips, belly, or thighs.
Other symptoms include:
• Redness
• Scabs
• Scaling
• Excessive scratching
Mites need veterinary diagnosis since they are microscopic. Some types are highly contagious.
Hot Spots or Skin Infections
Bacterial or yeast infections often develop on the lower back and hindquarters, especially in thick-coated dogs.
Hot spots appear suddenly as moist, painful, hairless patches. Dogs chew and lick the area, causing rapid hair loss.
Skin infections may also cause:
• Odor
• Oozing discharge
• Redness
• Itching
Moisture, friction, allergies, and grooming problems often trigger infections in this area.
Anal Gland Issues
Anal gland discomfort can cause dogs to chew or lick the back end excessively.
When glands become full, impacted, or infected, dogs may scoot, lick, or bite near the tail base. This leads to thinning hair, redness, or bald patches.
You may notice a fishy odor or signs of pain around the hindquarters. Hair loss improves once the anal glands are treated.
Hormonal Disorders
Cushing’s disease interrupts normal hair growth, causing slow-growing, thinning, or patchy fur.
Hair loss typically appears on the back, hips, and sides.
Other signs include:
• Increased thirst
• Pot-bellied appearance
• Muscle loss
• Thin skin
Cushing’s disease is more common in senior dogs and often causes symmetrical hair thinning.
Read more: Dog Losing Hair in Spots (What it means)
What to Do If Your Dog Is Losing Hair on the Back End
Start by checking the skin closely. Look for redness, bumps, dandruff, fleas, or signs of irritation.
Make sure your dog is on consistent flea prevention — even indoor dogs need monthly protection. Flea allergy dermatitis improves dramatically once fleas are under control.
Keep the area clean and dry. Moisture encourages yeast and bacteria to grow, which worsens hair loss.
Use a gentle, fragrance-free shampoo until the skin heals. Harsh shampoos may irritate sensitive areas.
Check your dog’s diet, especially if they’ve had allergies before. Switching to a limited-ingredient or hypoallergenic diet may help reduce inflammation.
Prevent excessive licking or chewing by using an e-collar, soft cone, or recovery suit temporarily. This protects the area while the skin heals.
Add omega-3 fatty acids or fish oil (vet-approved) to help soothe irritated skin and promote hair growth. These supplements support skin health long-term.
Observe for additional symptoms like lethargy, weight changes, or increased thirst.
These may point to hormonal issues rather than simple skin irritation.
If hair loss worsens or spreads, your dog needs a veterinary evaluation.
When to Call or Visit Your Vet
Seek veterinary care if your dog is losing hair on the back end and any of the following signs appear:
- If hair loss is severe, spreading, or patchy, your dog may have mites, infection, or allergies. Prompt diagnosis prevents worsening.
- If the skin looks red, swollen, crusty, or painful, an infection may be present. Hot spots or bacterial infections require treatment.
- If your dog is itching excessively, waking at night to scratch, or biting the skin, the discomfort may be significant. Allergies or mange could be involved.
- If there are signs of hormonal disorders, such as weight gain, a swollen belly, or lethargy, thyroid or adrenal disease may be the cause. These conditions require bloodwork.
- If fleas are present — even just one — dogs with flea allergies need immediate parasite treatment. Flea allergy dermatitis improves only with consistent prevention.
- If your dog scoots, licks the back end, or shows anal gland discomfort, the glands may need to be expressed or treated.
- If your dog has hair loss along the tail (“rat tail”), slow hair regrowth, or dull coat, hypothyroidism may be involved. Hormonal hair loss won’t resolve without medical treatment.
Read more: Dog Losing Hair on Hind Legs (Why it happens)
Key Takeaway
When a dog is losing hair on the back end, the most common causes are allergies, fleas, mites, infections, or hormonal disorders.
The back end is a high-risk area for irritation and inflammation, which means bald patches can develop quickly.
Early care, proper parasite control, and veterinary diagnosis when needed help restore healthy skin and prevent recurring hair loss. With the right treatment, most dogs recover fully and regrow their fur.