- September 1, 2026
- Dogs, Pet Health & Wellness
Dog allergies: why your dog itches and what helps
A dog who scratches, licks his paws or keeps getting ear infections may have an allergy. There are several kinds, and the right plan depends on which one your dog has. This guide explains the main types, how a veterinarian sorts them out and what treatment can do, for dog owners in Parma and across Northeast Ohio.
Key takeaways
- Flea bites, things in the environment such as pollens, molds and dust mites, and food can all trigger an allergy.
- Itching is the most typical sign. The feet, face, ears, front legs and belly are the areas most often affected.
- Environmental allergy is a lifelong condition. There is no cure, but most dogs can be treated successfully.
- Food allergy is diagnosed with a strict elimination diet trial, not a blood or skin test.
- Do not reach for human medicine. Common over-the-counter drugs can cause life-threatening problems in pets.
Signs of allergies in dogs
The Merck Veterinary Manual’s owner guide to allergies in dogs calls itching the most typical sign and lists the feet, face, ears, front legs and abdomen as the most frequently affected areas. Merck lists other signs as well, including licking or chewing the paws and rubbing the face and eyes, and adds that long-term or recurrent ear infections may be the only sign in a small number of dogs.
Cornell’s Riney Canine Health Center describes the same picture for atopic dermatitis, the environmental form: dogs scratch behind their elbows, lick and chew their feet, rub their faces and scoot. Over time there can be hair loss and red skin, and the hair where a dog licks may turn brown from salivary staining. If your dog’s paws have a rusty tint, that may be why.
Ears deserve their own mention. When Cornell asked an assistant clinical professor of dermatology about causes for ear scratching, her answer was “Allergies. Allergies. Allergies!” She explained that most dogs scratch at their ears because there is a little allergic inflammation first, and they then develop infections as a secondary problem.
Flea allergy: the first thing to rule out
The Merck Veterinary Manual explains that dogs with flea allergy dermatitis are sensitive to the saliva in flea bites, and that in dogs the itching and scabby lesions are found on the lower back, the base of the tail and the back and inner thighs. Most cases occur in late summer. In northern climates, though, Merck notes that the close association of pets and their fleas with our homes can make fleas a year-round problem.
Not seeing fleas does not rule them out. Merck points out that extremely sensitive animals can be virtually free of fleas because they groom so much. A simple check helps: slowly part the hair and look for dark flecks of flea dirt. Merck explains that flea dirt placed on a damp paper towel and crushed dissolves into a reddish-brown color.
The fix is steady prevention. The Companion Animal Parasite Council’s flea guidelines say all dogs should be treated year-round and throughout their life with flea control products, to limit infestations on the pet and prevent flea populations from becoming established in the home. Our older post on treatment of fleas covers the basics.
Environmental allergies (atopic dermatitis)
Cornell reports that atopic dermatitis may affect as much as 10 to 15 percent of the dog population. It is a reaction to allergens in the environment, including many types of pollens and molds, dust mites and dander. Atopic dogs typically start to show signs between 6 months and 3 years of age. The itching often has a seasonal component, in 40 to 75 percent of cases, but it can progress to a year-round condition.
There is no single test that proves a dog has it. Merck explains that diagnosis rests on age, breed, signs and history, after other causes are ruled out, and that allergy testing cannot diagnose allergies. What testing can do is identify the offending allergens so a veterinarian can build an immunotherapy plan. Cornell notes that testing can be done by watching how the skin reacts to small injected amounts of allergens or with a blood test for IgE antibodies, and that immunotherapy can be given by injection under the skin or under the tongue.
Immunotherapy takes patience. Merck says improvement may not be visible for 6 months, that a year of treatment may be needed before you can tell whether it is working, and that allergy shots improve the condition but do not cure it.
Food allergies
Food allergy is less common than environmental allergy, according to Merck, and one clue is that the itching changes little from one season to the next. Merck’s professional manual on cutaneous food allergy cites a review in which 1 to 2 percent of dogs receiving any form of veterinary care had some form of food allergy, rising to 9 to 40 percent of dogs with itching. It lists beef, dairy products, chicken, wheat and lamb as the most common food allergens in dogs.
Blood and skin tests are not reliable for diagnosing food allergy. Elimination diet trials remain the reference standard. During a trial, the dog eats only a diet of ingredients he has never eaten before, or a hydrolyzed prescription diet, and nothing else. Merck stresses that this includes treats, table food, flavored medications and toothpaste, along with rawhide chews, pill pockets and flavored toys. Merck cites a review that found a minimum of 10 weeks might be required to identify 95 percent of food-allergic patients, so plan on two to three months.
How a veterinarian sorts it out
Because these allergies look alike and a dog can have more than one, the work is mostly a careful process of elimination. A typical path through our illness and sick-pet care looks like this:
- History and exam. Where your dog itches, when it started, whether it changes with the season and what your dog eats.
- Rule out fleas and other parasites. Even when you have not seen a flea.
- Treat secondary infections. Cornell notes that secondary yeast and bacterial infections are common and require medication.
- Bring the itch under control. So your dog is comfortable while the cause is pinned down.
- Run a diet trial if the itching is year-round or food allergy is suspected.
- Consider allergy testing if environmental allergy is likely and you want to pursue immunotherapy.
- Set a long-term plan. Cornell notes that more challenging cases may benefit from a veterinary dermatologist.
What helps: treatment options
Most dogs need more than one approach, and the plan may change by season. Cornell lists the main medical options for atopic dermatitis. Corticosteroids are very effective in flare-ups, but because of side effects they are best used at the lowest effective dose for the shortest time. Cyclosporine and oclacitinib (Apoquel) both reduce itching with fewer side effects than corticosteroids. Lokivetmab (Cytopoint) is an injection usually given every 4 to 8 weeks. Antihistamines can be useful to prevent mild itchiness, but they are less effective once excessive itchiness is already present. Topical products such as shampoos and medicated wipes can help remove allergens and treat secondary bacterial and yeast infections.
The good news, in Cornell’s words, is that most atopic dogs can be treated successfully by working closely with a veterinarian to prevent and manage flare-ups.
When your dog’s plan includes a prescription, our prescription refill page explains the process. All prescriptions are subject to doctor approval. Please allow 12-24 hours for your prescription to be filled. If your pet has not been seen within the last 12 months and does not have the proper laboratory testing, the prescription cannot be filled.
Never give your dog human allergy, pain or cold medicine without asking your veterinarian. The ASPCA Animal Poison Control Center reports that human over-the-counter medications topped its list of pet toxins in 2018, and that ibuprofen, naproxen and cold and flu medicines can cause life-threatening problems such as stomach ulcers and kidney failure. It also advises treating chewable joint and allergy products for pets like prescription medicine and keeping them out of reach. If you think your dog swallowed something, call your veterinarian or the ASPCA Animal Poison Control Center at (888) 426-4435.
Hot spots and ear infections
Allergies often show up as one of these two problems. Cornell’s guide to hot spots, technically called moist dermatitis, names allergies and external parasites such as fleas as primary causes, and notes that warm weather usually brings more cases. These lesions are painful. If a sore is more than 24 hours old, Cornell says an infection is likely and a trip to the veterinarian is in order. In the meantime, an Elizabethan collar keeps your dog’s tongue off the area. Good flea and tick control is the most important preventive step.
Ears follow a similar pattern. Cornell’s guidance on itchy ear problems warns that over-the-counter ear mite products are not always effective and can sometimes cause more inflammation in the ear canal, and that the state of the eardrum, which your veterinarian checks, can influence which medications are safe to use. Swimming in lakes, rivers and streams is a common cause of ear infections, and Cornell advises keeping water out of your dog’s ears. Cornell adds that an emergency visit may be needed if an infection goes deeper into the middle ear, with signs such as a head held tilted to one side or a drunken gait.
Can dogs be allergic to grass or pollen?
Yes. Cornell lists numerous types of pollens and molds, dust mites and dander among the typical allergens in atopic dermatitis. The itching often has a seasonal component, but it can progress to a year-round condition. Your veterinarian will look at when your dog itches and what else could explain it before deciding whether testing for specific allergens makes sense.
How long does a food trial take for a dog?
Plan on two to three months. Merck’s owner guide says the trial diet should be fed for up to 3 months, and a review cited in Merck’s professional manual found that a minimum of 10 weeks might be needed to identify 95 percent of food-allergic patients. The trial only works if your dog eats nothing else, including treats, table food and flavored medications.
Can dog allergies be cured?
Environmental allergy is lifelong. Cornell says there is no cure, but effective treatment can help a dog keep a high quality of life, and Merck notes that allergy shots improve the condition without curing it. A confirmed food allergy, by contrast, is controlled by strict avoidance of the food behind it, as Merck explains.
Can I give my dog an antihistamine for itching?
Ask your veterinarian first. Cornell notes that antihistamines can be useful to prevent mild itchiness but are less effective when excessive itchiness is already present, and many dogs need a different medication. Products made for people can contain ingredients that are dangerous for dogs, and the ASPCA reports that cold and flu medicines can cause life-threatening problems in pets.
When to bring your itchy dog in
Call us if your dog’s itching is keeping either of you up at night, if a sore is more than a day old, if an ear looks red or has discharge, or if the problem keeps coming back. You can read more about dog health in our articles for dog owners.
Our hospital in Parma is open Monday to Friday from 7:30am to 5:30pm and is closed Saturday and Sunday. Call 440.845.7141 or request a visit, and we will help you find out what is behind your dog’s itch.
