Every dog scratches now and then. But when the scratching keeps you up at night, when your dog chews their paws raw or rubs their face along the carpet, something is wrong. Vets call itching pruritus, and it is one of the most common reasons dogs are brought in.
The tricky part is that many different problems cause the same itch, and a dog can have more than one at once. This guide walks through the most common causes in the same order many vets use to work through them.
What “itchy” can look like
Itch is not always obvious scratching. International veterinary allergy guidelines describe itch in dogs as scratching, rubbing, chewing, excessive grooming or licking, scooting, and head shaking. [1] Scooting can also point to anal gland problems.
Signs to watch for:
- Licking or chewing paws
- Rubbing the face or ears on furniture or the floor
- Scooting on the bottom
- Frequent head shaking
- Red skin, hair loss, darkened or thickened skin
- Brown staining of fur from saliva
The most common causes, and why the order matters
The International Committee on Allergic Diseases of Animals (ICADA) guidelines for vets list the main itchy skin diseases in dogs as parasites, skin infections and allergies. [1] Vets usually rule out parasites and infections before diagnosing allergies, because allergies have no single test that proves them. [1]
1. Fleas and flea allergy
Fleas are the first thing to check. Some dogs that are bitten again and again become allergic to proteins in flea saliva. This is flea allergy dermatitis, and once a dog is sensitized, just a few bites can set off a new flare. [2]
Where it itches: mostly the rump and lower back, the base of the tail and the back of the thighs, though some dogs itch all over. [1][2]
Why “I never see fleas” does not rule it out: a dog with flea allergy may carry very few fleas, yet a handful of bites is enough to keep the itch going. [1][2]
How to check: comb or brush through the coat with a fine-tooth flea comb and look for fleas or flea droppings (small dark specks). Your vet can do this at the visit too. [1]
What helps: ICADA notes that every itchy dog should be checked for fleas, and when none are found, an effective flea control program should be started to rule flea allergy out. [1] All dogs and cats in the home need treatment too, along with the environment. [1][2] Be patient: ICADA points out that flea pupae can survive in the environment for up to 174 days. [1]
2. Mites and other parasites
Several other parasites cause itch, including: [1]
- Sarcoptic mange (scabies), often intensely itchy
- Cheyletiella (“walking dandruff”), which can cause marked scaling along the back
- Ear mites, with dark brown, coffee-ground-like discharge in the ears
- Lice and chiggers (trombiculiasis)
- Demodex mites, which can appear alongside other conditions
These can be hard to tell apart by eye. [1] Your vet may use skin scrapings, combing, hair plucks, ear swabs or tape samples to look for them under the microscope. [1] Because scabies mites can be hard to find, ICADA strongly recommends a trial treatment in very itchy dogs where scabies is possible. [1] For more on scabies itself, see sarcoptic mange (scabies) in dogs.
3. Skin infections (bacteria and yeast)
Bacterial infections (pyoderma) and Malassezia yeast overgrowth are common in itchy dogs, especially allergic ones, and they make the itch worse. [1]
- Bacterial infection often shows as red bumps, pimples and round crusty rings. [1] See our guide to pyoderma in dogs.
- Yeast tends to cause redness, greasy yellowish or brownish scale and darkened skin, and salivary staining from licking is often associated with it. [1]
Your vet confirms these with cytology, a quick sample looked at under the microscope. [1] Treating infections first matters, because it shows how much itch is left over once they are gone.
4. Environmental allergies (atopic dermatitis)
Canine atopic dermatitis is a genetically predisposed, inflammatory, itchy allergic skin disease, most often linked to environmental allergens. [1] Depending on the allergen, the itch may be seasonal (for example pollen) or year-round (for example dust mites). [1]
If your dog itches only at certain times of year, see our guide to seasonal allergies in dogs.
Typical body areas: the face, the inside of the ear flaps, belly, armpits, groin, around the bottom, and the lower legs and paws. [1] Breed can change the pattern. [1]
Clues vets use: a set of clinical criteria (Favrot’s criteria) is used to judge how likely atopic dermatitis is. These include signs starting before 3 years of age, a mostly indoor lifestyle, affected front feet and ear flaps, and unaffected ear margins and lower back. [1] These criteria support the diagnosis but cannot prove it on their own. Other causes must be ruled out first. [1]
About allergy tests: ICADA explains that atopic dermatitis is diagnosed from the history and examination after ruling out look-alike diseases. Allergy testing (intradermal or blood tests) is then used to identify allergens for immunotherapy, not to diagnose the condition itself. [1]
5. Food allergy (cutaneous adverse food reaction)
A reaction to food can look exactly like environmental allergy. [1] Clues that food may be involved include year-round itch and gut signs such as diarrhea, vomiting, soft stools, gas or more frequent bowel movements. [1]
There is no reliable blood, saliva or hair test for food allergy. ICADA states that food allergy can only be ruled out by a strict elimination diet trial, since accurate diagnostic commercial tests are not currently available. [1]
How an elimination diet works: [1]
- Your vet chooses a diet with ingredients your dog has not eaten before, or a suitable prescription diet.
- The diet is fed exclusively (no treats, table scraps or flavored medicines unless your vet approves) for at least 8 weeks.
- If itch improves, the old food is reintroduced. A relapse confirms that diet plays a role.
Most common food triggers: a review of the evidence found that the most likely food allergens in dogs are beef, dairy products, chicken and wheat. [3]
6. Other causes
ICADA’s list of itchy skin diseases also includes insect bite hypersensitivity, contact dermatitis and, rarely, a skin cancer called cutaneous lymphoma. [1] This is one more reason a persistent itch should be checked by a vet, especially in an older dog with no previous skin problems.
If the main problem is flaking or bald patches rather than itch, see dog dandruff and dry, flaky skin and hair loss in dogs.
If itchy bumps or a puffy face appeared suddenly, see hives and facial swelling in dogs.
How your vet puts it together
Expect a step-by-step approach rather than one test. Based on the ICADA guidelines, a typical workup looks like this: [1]
- Rule out fleas with combing and a strict flea control trial for every pet in the home.
- Rule out other parasites with skin scrapings, tape samples and sometimes trial treatment.
- Find and treat bacterial or yeast infections with cytology-guided treatment.
- Consider food with an elimination diet trial, especially if the itch is year-round or there are gut signs.
- Diagnose atopic dermatitis if the itch remains and the pattern fits, then discuss allergy testing for immunotherapy.
These steps can be done over several visits or all at once, depending on your dog. [1]
How itch is usually managed
Treatment depends on the cause. For dogs with atopic dermatitis, the ICADA treatment guidelines describe a combined approach: [4]
- Find and avoid flare factors such as fleas, food and infections.
- Skin and coat care, which may include more frequent bathing with mild shampoos and possibly added essential fatty acids.
- Prescription anti-itch medicines chosen by your vet. ICADA describes several topical and oral options for long-term itch control; your vet will pick one that suits your dog.
- Allergen-specific immunotherapy (“allergy shots” or drops), which ICADA notes is one of the only interventions likely to prevent or delay flares.
ICADA stresses that treatment plans vary between dogs, and for the same dog at different stages. [4] Allergies are usually managed, not cured, so expect ongoing care and rechecks.
Do not give human allergy or pain medicines without your vet’s advice. The FDA warns that common human pain relievers can seriously harm dogs, and advises calling your vet before giving any medication. [5]
When to see your vet
Book a visit if:
- The itch lasts more than a few days or keeps coming back
- You see red skin, bumps, scabs, hair loss, odor or greasy skin
- Your dog is licking their paws, rubbing their face or shaking their head often
- Ears are red, smelly or have discharge (see our guide to ear infections in dogs)
- Itch is disturbing your dog’s sleep
Go promptly if the skin is broken, oozing or painful (it may be a hot spot or infection; if your dog has scratched the skin open, see our minor wound care guide), if your dog seems unwell, or if other pets or people in the home are suddenly itchy too.
Frequently asked questions
What is the most common cause of itching in dogs?
Fleas, other parasites, skin infections and allergies (environmental and food) are the main causes. [1] Where fleas are common, flea allergy is a frequent culprit, so vets check for it first. [1][2]
My dog has no fleas. Can it still be flea allergy?
Yes. An allergic dog can react strongly to only a few bites, so you may find few or no fleas on the coat. [1][2] That is why vets recommend a strict flea control trial for all pets in the home before ruling it out. [1]
Can a blood test tell me if my dog has a food allergy?
No. According to ICADA, food allergy can only be ruled out with a strict elimination diet trial, because accurate commercial tests are not currently available. [1]
How long does an elimination diet take?
ICADA recommends feeding the trial diet exclusively for at least 8 weeks, then rechecking with your vet. [1]
What foods are dogs most often allergic to?
An evidence review found beef, dairy products, chicken and wheat to be the most likely food allergens in dogs. [3]
Why does my dog lick their paws so much?
Paw licking is a common sign of itch. The paws and lower legs are among the areas most often affected by atopic dermatitis [1], and yeast or bacterial infections can make it worse. [1] See your vet to find the cause, and see our guide to dog paw problems.
Can allergies in dogs be cured?
Usually they are managed rather than cured. ICADA describes a combination of avoiding flare factors, skin care and medication, with allergen-specific immunotherapy among the only options likely to prevent or delay flares. [4]
The bottom line
An itchy dog is telling you something, but the itch alone does not say what. Fleas, mites, infections and allergies can all look alike and often occur together. A step-by-step workup with your vet, starting with parasites and infections and moving on to food trials and environmental allergy, is the fastest route to real relief.
See your vet if your dog’s itch lasts more than a few days, keeps coming back, or comes with broken skin, odor or ear problems.
This article is for general information only and is not a substitute for professional veterinary advice, diagnosis or treatment. Always consult your veterinarian about your pet’s health. If you think your pet has a medical emergency, contact your veterinarian or an emergency animal hospital right away.
Sources
- Hensel P, Santoro D, Favrot C, Hill P, Griffin C. Canine atopic dermatitis: detailed guidelines for diagnosis and allergen identification (ICADA). BMC Veterinary Research. 2015;11:196. doi:10.1186/s12917-015-0515-5. https://pmc.ncbi.nlm.nih.gov/articles/PMC4531508/
- Crosaz O, Chapelle E, Cochet-Faivre N, et al. Open field study on the efficacy of oral fluralaner for long-term control of flea allergy dermatitis in client-owned dogs in Ile-de-France region (background section). Parasites & Vectors. 2016;9:174. doi:10.1186/s13071-016-1463-z. https://pmc.ncbi.nlm.nih.gov/articles/PMC4806425/
- Mueller RS, Olivry T, Prelaud P. Critically appraised topic on adverse food reactions of companion animals (2): common food allergen sources in dogs and cats. BMC Veterinary Research. 2016;12:9. doi:10.1186/s12917-016-0633-8. https://pmc.ncbi.nlm.nih.gov/articles/PMC4710035/
- Olivry T, DeBoer DJ, Favrot C, et al. Treatment of canine atopic dermatitis: 2015 updated guidelines from the International Committee on Allergic Diseases of Animals (ICADA). BMC Veterinary Research. 2015;11:210. doi:10.1186/s12917-015-0514-6. https://pmc.ncbi.nlm.nih.gov/articles/PMC4537558/
- U.S. Food and Drug Administration. Get the Facts about Pain Relievers for Pets. https://www.fda.gov/animal-veterinary/animal-health-literacy/get-facts-about-pain-relievers-pets