Where Does It Itch? 3 Common Dog Allergies And How You Might Be Able To Tell Them Apart

by Dr. Anna M. Coffin, DVM

Itching is the most common symptom for allergies in dogs.  

There are three common dog allergies.  If your pet is itchy, this article will help you identify the cause.

3 key factors are used to help diagnose these three common dog allergies:
  • Where on the body is your dog itchy
  • At what age does the itching begin
  • What time of year is your pet itchy
Food allergies

Food allergies are caused from an allergy to either the protein or carbohydrate source found in your dog’s food.

Dogs with food allergies are itchy primarily in the face, feet, ears and rear.   

Food allergies can occur in any age dog, but should be highly suspected if your dog becomes itching between 6-12 months of age. Because your pet is constantly exposed to the food, this type of allergy occurs all year around.

Reoccurring ear infections are very common in dogs with food allergies.  

Diagnosis is made by a food elimination trial which involves placing your dog on a prescription diet with no other food or treats for 6-8 weeks.  Once diagnosed, treatment is simple and involves strict diet control.

Flea allergy dermatitis (FAD)

Flea allergy dermatitis is caused from a reaction that your pet has to flea saliva.

Dogs with FAD are primarily itchy at the base of their tail.  

Flea allergy dermatitis can occur in any age dog and it also a very common problem in cats.  This type of allergy is usually seen only during flea season.

This is the easiest allergy to treat!  A flea eradication program for all pets that live in the household and treating the environment will resolve the problem.

However, dogs can be itchy for up to one month after the bite of just one flea.  Fortunately, the itching can be relieved by giving your dog steroids prescribed by your veterinarian.

Inhalant allergies (Atopy)

Inhalant allergies, also known as atopy, are caused from environmental allergens such as grass, trees, pollen and mold.

Dog with atopy are itchy all over their body and not in a specific area like food or flea allergies.  

Symptoms for inhalant allergies usually develop in dogs between 1-3 years of age.

Dogs with atopy are usually itchy only during a portion of the year when the allergen they are allergic to is high in the environment. Diagnosis is usually made by ruling out the two other types of allergies. However, skin and blood testing can be performed to help determine what your pet is allergic to.

Here is a recent article I wrote about treatment options for inhalant allergies.

Some dogs can have all three types of allergies which makes diagnosis and treatment more difficult. 

Generally, dogs with all three allergies are less itchy in the winter, especially if they are on a diet specifically for their food allergies.


Dr. Anna was born and raised in Guthrie, Oklahoma. As a teenager, Dr. Anna found her beloved pet dead on the side of the road left to die without any help. That was the moment she decided to become a vet and vowed to help other people and their pets. After a few years of practicing in New Hampshire, Dr. Anna became homesick and decided to return to Guthrie to be with her parents and five other siblings. Family and friends are a major part of our lives which is why we treat our clients at Guthrie Pet Hospital as family.  Dr. Anna and her husband do not have children but are very proud pet parents and therefore, treat every four legged friend as part of the family.