When your dog starts losing hair and constantly itching, it’s a clear sign the skin is irritated or reacting to something in the environment.
Hair loss combined with scratching, biting, or chewing often points to conditions that need attention before they worsen.
We outline the common causes of hair loss and itching in dogs, what you can do at home, and when to seek veterinary help.
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Dog Losing Hair and Itching — Why It Happens
Dogs lose hair and itch excessively when their skin becomes irritated by allergens, parasites, fungal or bacterial infections, or hormonal imbalances that affect skin health. Itching causes dogs to scratch or chew aggressively, damaging hair follicles and pulling out hair in patches. This creates bald patches, broken hair, redness, and sometimes scabs. The longer the irritation continues, the more severe the hair loss becomes.
Allergies and parasites are the most common triggers, but infections or hormonal disorders can also weaken the skin’s barrier and cause shedding, flaking, and inflammation.
Without treatment, hair loss usually gets worse and can spread across the body.
Dog Losing Hair and Itching: Common Causes
Flea Allergy Dermatitis
Flea allergy dermatitis is one of the most frequent reasons dogs itch and lose hair. A dog with a flea allergy reacts strongly to flea saliva, causing intense itching even from a single bite.
Dogs then scratch, chew, or gnaw at their skin—especially near the tail base, back, and thighs—leading to bald spots, redness, and scabs.
Because fleas hide deep in the coat and spend much of their life cycle off the dog (in bedding, carpets, or outdoors), many owners miss the signs.
The dog often shows the symptoms of an allergy long before fleas are actually seen. Severe scratching can also introduce bacteria, creating secondary infections that worsen hair loss.
Read more: Dog Losing Hair in Patches and Scabs (Why it happens)
Environmental Allergies
Environmental allergies cause year-round or seasonal itching that often affects the paws, belly, armpits, and ears — but hair loss frequently appears on the body where dogs scratch the most.
When allergens touch the skin or enter through inhalation, the immune system overreacts, making the skin itchy, inflamed, and irritated.
Dogs rub against furniture, scratch with their paws, or bite the itchy area, leading to hair breakage and patchy bald spots.
Over time, the skin may appear red, flaky, or thickened. Environmental allergies tend to be chronic, meaning symptoms often recur unless the underlying trigger is managed.
Food Allergies
Food allergies commonly cause both itching and hair loss, especially when the dog reacts to ingredients like chicken, beef, eggs, dairy, or wheat.
These allergies are often misunderstood because the itching does not always accompany digestive issues. Many dogs with food sensitivities show only skin-related symptoms.
Scratching is typically worse on the face, paws, belly, and ears, but widespread irritation can cause hair loss over the body.
Dogs may lick their paws obsessively, chew their legs, or rub their face on the ground. The skin may develop bumps, hot spots, or ear infections due to chronic inflammation.
Mange
Mange is caused by microscopic mites that irritate the skin and cause intense itching and hair loss.
Demodectic mange often produces round patches of hair loss that appear smooth or scaly. Sarcoptic mange (scabies) is extremely itchy and spreads quickly, often affecting the ears, elbows, chest, and belly.
Dogs with mange scratch intensely, leaving bald spots, crusts, scabs, and inflamed skin.
Because mange can mimic allergies or infections, only a vet can confirm the diagnosis with skin scraping. Mange spreads rapidly and may become severe without prescription treatment.
Bacterial or Yeast Skin Infections
Secondary skin infections often develop when a dog scratches repeatedly, breaking the skin and allowing bacteria or yeast to multiply. These infections can cause localized or widespread hair loss along with:
• Redness
• Flakes
• Oily skin
• Sticky patches
• A sour or musty smell
Yeast infections commonly develop in warm, moist areas such as the armpits or groin, while bacterial infections may appear as red bumps, pustules, or crusty scabs. These conditions cause constant itching, making the cycle of irritation and hair loss worse.
Hot Spots
Hot spots form when a dog licks or scratches one area intensely, creating a moist, inflamed, painful skin lesion. Hair around the area falls out quickly, leaving a bald patch that may look raw, red, or covered in sticky discharge.
Hot spots often start from:
• A flea bite
• An allergy flare
• Moisture trapped under the coat
• Grooming irritation
Because bacteria multiply rapidly in these warm, moist patches, hot spots can grow within hours. Dogs often continue licking the area, making treatment important to stop the cycle.
Hormonal Disorders
Hormonal imbalances can weaken the skin and disrupt the hair growth cycle. Hypothyroidism can make the coat dry, brittle, and prone to patchy shedding.
Cushing’s disease causes thinning skin, slow healing, and symmetrical hair loss along the flanks and body.
Unlike allergies or parasites, hormonal hair loss usually does not itch initially, but dogs often develop secondary infections because the skin becomes fragile. When infections occur, itching and further hair loss follow.
What to Do If Your Dog Is Losing Hair and Itching
First, examine your dog’s skin gently. Look for fleas, redness, flakes, bumps, or black specs (flea dirt). If fleas are present or suspected, start a vet-approved flea preventive immediately — even if you only see one flea. Wash bedding and vacuum carpets to remove eggs and larvae.
If the skin is red, irritated, or moist, gently clean the area with a mild, pet-safe antiseptic wash. Avoid using human creams or random over-the-counter ointments, which can worsen the irritation or trap moisture.
If allergies are suspected, try eliminating recent food changes or environmental triggers when possible. Using a bland diet temporarily may help calm inflammation while you wait for a vet visit.
Omega-3 supplements, probiotics, and regular grooming can support skin health, but these are supportive measures, not cures for underlying conditions.
Most importantly, prevent your dog from scratching excessively. An Elizabethan collar (cone) may be needed to stop them from damaging the skin further.
When to Call or Visit Your Vet
It’s important to seek veterinary care if the itching or hair loss is persistent, spreading, or accompanied by skin damage. Many causes cannot be resolved without prescription treatment.
Call your vet if your dog has:
• Intense itching disrupting sleep
• Red, raw, or bleeding skin
• Circular bald patches
• Thickened or darkened skin
• Oozing wounds or foul-smelling areas
• Rapid spreading of bald spots
• Hair loss combined with lethargy or appetite loss
Early treatment prevents chronic skin issues and helps the hair regrow faster.
Read more: Dog Losing Hair in Patches on Back (Common causes explained)
Key Takeaway
When a dog is losing hair and itching, it’s almost always due to irritation from fleas, allergies, mites, or infections — or less commonly, hormone disorders.
Because the constant scratching makes hair loss worse, early diagnosis and treatment are the best ways to help your dog heal and feel comfortable again. With proper care, most dogs fully recover and regrow their coat.