My Dog Is Itching and Losing Hair: 8 Common Causes and What to Do

Quick answer: If your dog is itching and losing hair, the most common causes are fleas (including flea allergy), environmental allergies, food allergies, mites (mange) and bacterial or yeast skin infections. Hair loss with little or no itching points more toward hormonal disease such as hypothyroidism or Cushing's disease. Open sores, crusts, a bad smell or patches that keep spreading need a vet visit.

If you have been saying "my dog is itching and losing hair" for weeks, you are not alone. Itchy skin is one of the most common reasons dogs see a vet. The good news is that in most itchy dogs, the hair loss is not a separate problem. It is the result of the itch, which means that once you find and treat the cause, the coat usually grows back.

This guide walks through the 8 most common causes, what the location of the bald patches can tell you, what to check when you cannot find fleas, and when it is time to call your vet.

Why itching and hair loss happen together

Vets call itching "pruritus" and hair loss "alopecia." When both appear together, they usually follow the same loop:

1. Something triggers inflammation in the skin, such as a flea bite, pollen or a food protein.
2. The inflamed skin itches, so your dog scratches, licks, chews or rubs.
3. That constant friction breaks hairs off and damages the follicles, leaving thin spots and then bald patches.
4. Broken skin lets bacteria and yeast multiply, which makes the itch worse and keeps the loop going.

That is why treating only the bald patch rarely works. You need to stop the trigger and break the loop.

8 common causes of itching and hair loss in dogs

1. Fleas and flea allergy dermatitis

Fleas are still the number one cause of an itchy dog losing hair. Many dogs are allergic to flea saliva, and in an allergic dog a single bite can cause days of intense itching. The classic pattern is hair loss, redness and scabs over the lower back, the base of the tail and the backs of the thighs.

Not seeing fleas does not rule them out, because itchy dogs often groom them off. Run a flea comb through the coat over a white paper towel, then dampen the specks. If they smear reddish-brown, that is flea dirt (digested blood) and fleas are present.

2. Environmental allergies (atopic dermatitis)

Pollen, dust mites, mold and grasses are among the most common triggers of chronic itching in dogs. The itch often starts seasonally and can become year-round over time. It usually focuses on the paws, face, ears, armpits, belly and groin, so you will see paw licking, face rubbing, red bellies and repeat ear infections. It often first appears in young adult dogs.

3. Food allergies

Food allergies are less common than environmental allergies, but they cause itching that does not follow the seasons. The ears, paws, face and rear end are typical hot zones, and some dogs also have soft stools, gas or occasional vomiting. Beef, dairy, chicken and wheat are the most commonly reported triggers in dogs.

The only reliable way to confirm a food allergy is a vet-guided elimination diet that runs for 8 to 12 weeks, and it fails if anything else sneaks in, including treats. Ask your vet before adding any treat to a trial. If fish has not been part of your dog's diet and your vet approves it, single-protein options like our dog treats for allergies keep the trial clean.

4. Mites (sarcoptic and demodectic mange)

Sarcoptic mange causes some of the most intense itching a dog can have. Hair loss and crusts usually start on the ear edges, elbows, hocks and belly. It spreads easily between dogs and can cause a temporary itchy rash in people.

Demodectic mange is different. Demodex mites live in every dog's hair follicles, but an overgrowth causes patchy hair loss, often around the eyes, muzzle and front legs. It is usually not very itchy at first and becomes itchy when infection sets in. It is most common in puppies and dogs with weakened immune systems. Your vet diagnoses both types with a skin scraping.

5. Bacterial skin infection (pyoderma)

Bacterial infections are usually secondary to allergies or fleas. Look for red bumps, pimple-like pustules, crusts, circular rings of scaly skin and a moth-eaten look to the coat, which is especially easy to see in short-coated dogs. These need a vet exam because many dogs need medicated shampoo, antibiotics or both.

6. Yeast infection (Malassezia)

Yeast overgrowth makes the skin greasy, smelly and itchy. Over time the skin can darken and thicken. It shows up between the toes, in the ears, in the armpits, in skin folds and on the belly. Reddish-brown staining on light-colored paws from constant licking is a common clue. Like bacterial infection, yeast is usually riding on top of an allergy.

7. Ringworm

Ringworm is a fungal infection, not a worm. It causes round patches of hair loss with scaly or crusty edges, often on the face, ears and paws. The itch can be mild, so some owners do not notice it until patches appear. Ringworm can spread to people and other pets, especially children and cats, so see your vet if you notice round bald spots.

8. Hot spots and lick dermatitis

A hot spot (acute moist dermatitis) is a wet, red, painful patch of matted fur that can appear within hours, often on the neck, hips or cheek. Anything that starts an itch can trigger one, and moisture trapped in a thick coat after swimming or bathing makes them more likely.

Acral lick dermatitis is a thick, raised, hairless sore, usually on the lower front leg, caused by constant licking of one spot. It can be driven by boredom, anxiety, joint pain or allergies.

My dog is itching and losing hair but has no fleas

This is one of the most searched versions of this problem. Work through it in this order:

1. Recheck for fleas properly. Use a flea comb and the wet paper towel test above, and check every pet in the home. Keep all of them on vet-recommended flea prevention, year-round.
2. Look at the timing. Itching that flares in spring and summer points toward environmental allergies. Itching that stays the same all year, especially with digestive signs, points toward food.
3. Check for infection. A greasy coat, musty smell, pustules or crusts mean bacteria or yeast are involved and your dog needs a vet visit.
4. Ask who else is itchy. If other pets or family members are scratching too, mites or ringworm move up the list.
5. Think about recent changes. A new shampoo, carpet cleaner, laundry detergent, lawn treatment or bed can cause contact irritation on the belly, paws and chin, where the hair is thinnest.

For ways to calm the scratching while you investigate, see our guide on how to stop your dog from scratching and biting its skin.

What the pattern of hair loss can tell you

Where your dog is itching and losing hair is one of the first things your vet will look at.

If your dog is losing hair but not itching

Hair loss without much itching is more often internal than allergic. Hypothyroidism can cause thinning on both sides of the body, a dull coat, a thin "rat tail," weight gain and low energy. Cushing's disease can cause thin skin, a pot belly, heavy panting and more drinking and peeing. Seasonal flank alopecia, coat changes after clipping and normal heavy shedding are other possibilities. Your vet can check thyroid and adrenal function with bloodwork. These dogs can still become itchy later if a secondary skin infection develops.

When to take your dog to the vet

Book a vet visit if you notice any of these:

• Open sores, bleeding, pus or a bad smell
• Bald patches that are spreading, or new ones every week
• Itching that keeps your dog awake or makes them chew their skin raw
• Crusts on the ear edges or elbows, or itchy people or pets in the home
• Round bald patches, especially if you have children or cats
• Weight change, more thirst or urination, low energy or a pot belly
• Itching that continues after you have treated every pet for fleas

To find the cause, your vet may use a flea comb exam, a skin scraping for mites, tape or swab samples to look for bacteria and yeast, a fungal culture for ringworm, bloodwork for thyroid and adrenal problems, an elimination diet for food allergies, or allergy testing for environmental triggers.

How to help your dog at home while you find the cause

• Keep every pet on vet-recommended flea prevention, every month, all year.
• Break the itch-scratch loop with a cone or a soft recovery suit so damaged skin can heal, and keep nails trimmed.
• Wipe paws and belly after walks during allergy season, and wash bedding weekly in hot water.
• Bathe with a gentle, fragrance-free shampoo your vet recommends, and dry thick coats all the way to the skin.
• Keep a simple itch diary: the date, where your dog is itching, what they ate and where they walked.
• Do not put human creams, tea tree oil or other essential oils on your dog's skin. Some are toxic to dogs and can be licked off.

For gentle, vet-friendly options such as oatmeal soaks, see what you can give your dog for itchy skin naturally.

Can diet and treats help with itchy skin and hair loss?

Diet will not fix fleas, mites or infection, but it matters in two ways.

It can remove hidden triggers. If a food allergy is possible, the treat jar is where chicken, beef, dairy and wheat most often slip back in. A treat with one ingredient is the easiest to rule in or out. Our guide to the best dog treats for dogs with allergies explains what to look for, and how to read a freeze-dried dog treat label shows you how to spot the hidden extras.

It can support the skin barrier. Omega-3 fatty acids (EPA and DHA) support skin barrier function and help moderate inflammation. They are not a cure for allergies, and visible coat changes usually take six to eight weeks. Our freeze-dried mackerel dog treats contain 6.5 g of EPA and DHA per 100 g, the most of our three fish.

If your dog has a confirmed fish allergy, choose a different protein with your vet's help. For every other dog, browse our single-ingredient dog treats: one wild-caught fish, no grain, no chicken, no beef and nothing else to guess about.

The bottom line

When your dog is itching and losing hair, the bald patches are usually a symptom of the itch, not the problem itself. Start with fleas, read the pattern, note the timing and get a vet involved early if you see sores, crusts, smells or spreading patches. Once the cause is under control, most dogs grow their coat back. Keeping treats simple makes it much easier to see what is working.

Shop hypoallergenic dog treats made from a single wild-caught fish.

This article is for general information and is not a substitute for advice from your veterinarian.

Frequently asked questions

Why is my dog itching and losing hair?

Most of the time the hair loss is caused by the itch itself: scratching, licking and chewing break the hair and damage the follicles. The most common triggers are fleas, environmental allergies, food allergies, mites, and bacterial or yeast skin infections. A vet can usually narrow it down with a flea check, a skin scraping and a skin sample.

My dog is itching and losing hair but has no fleas. What else could it be?

First make sure there really are no fleas, because itchy dogs often groom them off; a flea comb and the wet paper towel test are more reliable than looking. If fleas are ruled out, the usual causes are environmental allergies, food allergies, mange mites, yeast or bacterial infection, and contact irritation from shampoos, cleaners or lawn treatments.

Why is my dog scratching and losing hair in patches?

Patchy hair loss with scratching often points to a localized problem: flea allergy on the lower back and tail base, mites on the ear edges, elbows or around the eyes, ringworm in round scaly patches, bacterial infection in crusty rings, or a hot spot in one wet, red patch. Patches that spread, crust or smell need a vet exam.

What causes itchy skin and hair loss in dogs?

Itchy skin and hair loss in dogs usually come from allergies (environmental, food or flea), parasites (fleas, mites or lice) or skin infections (bacteria, yeast or ringworm). Less often, the cause is behavioral licking, contact irritation, or a hormone problem that has led to a secondary infection.

Why is my dog losing hair near the tail and itching?

Hair loss and scabs over the lower back, tail base and backs of the thighs are the classic pattern of flea allergy dermatitis. One bite can set off days of itching in an allergic dog, so consistent, year-round flea prevention for every pet in the home is the first step.

Why is my dog licking its paws and losing hair on its belly?

Paw licking with redness or hair loss on the belly, armpits and groin is typical of allergies, either environmental (pollen, dust mites, grass) or food. A musty smell or darkened, greasy skin suggests a yeast infection has developed on top of the allergy.

Why is my dog losing hair but not itching?

Hair loss without much itching is more often caused by hormonal disease such as hypothyroidism or Cushing's disease, seasonal flank alopecia, early demodectic mange, or heavy shedding. Even thinning on both sides of the body, weight change or increased thirst are reasons to ask your vet about bloodwork.

Can food allergies cause itching and hair loss in dogs?

Yes. Food allergies cause year-round itching, often around the ears, paws, face and rear end, and the scratching leads to hair loss. Beef, dairy, chicken and wheat are the most commonly reported triggers, and a vet-guided elimination diet of 8 to 12 weeks is the only reliable way to confirm a food allergy.

Is my dog's itching and hair loss contagious?

Sometimes. Sarcoptic mange spreads easily to other dogs and can cause a temporary itchy rash in people, and ringworm can spread to people and other pets. Allergies, yeast infections, demodectic mange and hormonal hair loss are not contagious. Tell your vet if other pets or family members start itching.

Will my dog's hair grow back?

In most cases, yes. New growth usually appears within a few weeks of the itch being controlled, and a full coat can take several months, longer in double-coated breeds. Scarring from deep infections or years of licking can leave permanent thin spots.

When should I take my dog to the vet for itching and hair loss?

See your vet if you notice open sores, pus, crusts, a bad smell, spreading patches, or itching that keeps your dog awake. Go sooner if there are other signs such as weight change, increased thirst or low energy, or if itching continues after you have ruled out fleas.

Can fish treats help a dog with itchy skin and hair loss?

They can support skin health, but they will not cure the underlying cause. Single-ingredient fish treats avoid the most common food triggers and provide omega-3 fatty acids (EPA and DHA) that support the skin barrier, with visible coat changes usually taking six to eight weeks. If your dog has a fish allergy, choose a different protein with your vet.