Pet Health Library

Allergies in Dogs

Dog in the grass scratching

Background

The immune system is the body’s defense against anything that is foreign such as bacteria, viruses, or parasites. Allergies occur when a dog’s immune system overreacts to a substance that isn’t a health threat. Those substances are called allergens.

Allergic dermatitis, also known as atopy, refers to allergies to things in the environment such as dust mites, pollen, mold, trees, grass, fleas, or even another pet. The condition occurs when a dog encounters an allergen either by inhaling it or through direct contact with the skin. Direct contact with the skin explains, in part, why the feet and face can be so itchy — these are the parts of a dog’s body that are most in contact with allergens. Environmental allergies may be either seasonal or year-round depending on if the allergen is seasonal like pollen or present year-round like dust mites.

Food allergies are much less common in pets than environmental allergies. When they occur, the dog tends to be allergic to common ingredients in food such as beef, chicken, milk, soy, or eggs.

Much as they are for humans, allergies for dogs are itchy, irritating, frustrating, and sometimes painful. On top of this, the itching, scratching, and licking can lead to infections.

Risk Factors

Most allergic dogs begin to show signs when they are between six months and three years old. Any dog can develop environmental allergies, but the condition is more common in the following breeds:

  • Boston terriers
  • Boxers
  • Dalmatians
  • Golden retrievers
  • Labrador retrievers
  • Lhasa apsos
  • Scottish terriers
  • Shar-peis
  • Shih tzus
  • West Highland white terriers
  • Wirehaired fox terriers

Any dog can develop food allergies, but there may be an increased risk for the following breeds:

  • Cocker spaniels
  • Labrador retrievers,
  • West Highland white terriers

Signs

  • Itching
  • Scratching: The feet, face, ears, front legs, and abdomen are most often affected, but scratching all over the body is also common.
  • Scratching can lead to secondary signs of wounds, scabbing, skin and ear infections, hair loss, and scaling.
  • Licking or chewing the paws
  • Rubbing the face and eyes

Signs of food allergy are similar to those of environmental allergies except there is little variation from one season to another. Gastrointestinal signs such as chronic vomiting, diarrhea, belching, and frequent bowel movements also may occur.

skin patch test dogs

Diagnosis

Diagnosis is based on age, breed, signs, and history. Other causes of itching such as bacterial infection and skin parasites also must be eliminated. Allergy testing can be used to identify the allergen, which is helpful for creating a treatment plan.

Keeping a detailed history of your dog’s itching problem will be useful for the diagnosis. This means monitoring the signs, when the signs occurred, what happened before the onset of the signs, and response to any treatments.

The standard method for determining if food is the cause of the allergy is a diet elimination trial. Elimination diets contain a limited number of ingredients and protein sources not typically found in common pet food — and not previously fed to your dog. An elimination diet requires determination on the part of the pet owner to tough out six to eight weeks of strict dietary control. If the itching resolves on the diet elimination trial, additional foods slowly may be added to the diet while your dog is monitored for itching.

Treatment

It is not possible to cure environmental allergies, but they can be managed. An effective treatment plan may involve several different approaches:

Reduce Allergens  Simply wiping your dog’s face and paws when coming in from outside will help reduce the allergens and thus the chewing and licking. If your dog is itchy all over, a nice soothing bath will help calm the skin.

Parasite Control  One of the top causes of canine allergies stems from a reaction to flea saliva. A flea bites your dog, setting off an allergic reaction. Fortunately, numerous options for controlling fleas are available. Your veterinarian can help you determine which product best fits your dog’s needs.

Medication A variety of drugs can be used to turn off the allergic reaction underlying the itch-scratch cycle in your pet.

  1. Antihistamines Over-the-counter antihistamines are sometimes used to treat mild clinical signs of allergies in dogs.
  2. Steroids Prednisone and other steroids can relieve itching and the resulting inflammation; however, their side effects (increased water drinking, increased urination, and increased appetite) limit long-term use in allergy management.
  3. Prescription allergy medications More commonly, veterinarians use prescription medications to help manage allergies in dogs. Some of the drugs are human medications, but one canine-specific treatment, oclacitinib, inhibits the pathway inside the cell responsible for turning on the itch-scratch cycle.

Immunotherapy Retraining the immune system to turn off the triggered response has been used in allergy management for decades in the form of “allergy shots.” Allergy shots contain a small amount of the trigger substance and, when given at regular intervals, teach the immune system to ignore the trigger.

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Dermatology

About Dermatology at AMC

The Animal Medical Center’s staff Dermatologist has a breadth of training and experience in recognizing, diagnosing, and treating diseases of the skin of animals, including the ear, hair, nail, hoof, and mouth. While some veterinary skin diseases are similar to conditions in humans, most are unique and may occur in only one of the many types of animals a vet...

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