Pets can suffer from seasonal allergies just like people! Unlike us, instead of suffering from congestion, our pets allergies manifest through their skin. With spring in full bloom here in the Ohio River Valley, our clinic is seeing an increase in the number of pets affected by allergies. There are three main types of allergies and while our pets don’t read textbooks and always follow these patterns, certain allergies have a typical presentation. We will discuss how we differentiate these types of allergies through our physical exam, diagnostics, and treatment.


The first and most common type of allergy is atopy. Atopy is a hypersensitivity to environmental factors that a pet either inhales or comes into physical contact with. Many substances can cause atopy such as pollen, dust mites, mold spores, and other environmental allergens. We often diagnose atopy based on clinical signs and by first ruling out other types of allergies or additional causes of skin disease. Atopy can lead to secondary infections of both the skin and ears. Intradermal or serum testing can be useful in creating specific treatment but is not used for making a diagnosis. Immunotherapy for atopy will be required for the life of the pet. If it is seasonal, you may be able to stop treatment during the quiet months. In many cases, however, treatment will be required year round. 

Clinical Signs of Atopy:
  • Pruritus (itchiness) 
  • Redness of the skin 
  • Most affected areas: face, ears, underside of belly, backs of legs/ elbows, feet, and under the tail. 
  • Areas that are in more contact with our rugs/ carpets, grasses, etc. are often affected more severely 
  • May be seasonal
  • Age of onset: 6 mo – 3 years 
  • Diagnosis of exclusion – Rule out other causes of skin disease.
  • Immunomodulators
    • Cytopoint injections 
    • Apoquel 
  • Steroids may be required in extreme cases to get the itch cycle under control
  • Allergen specific immunotherapy (allergy shots)
  • Omega 3 & 6 fatty acids 
  • May require additional treatment to control secondary infections

Flea Allergy Dermatitis 

This is an extremely common allergy in our pets. This is one of the many reasons we recommend monthly flea and tick prevention for all pets! One of the classic aspects of flea allergy is pruritus and dermatitis affecting the back half of the body, especially the base of the tail and under the tail. Some pets may be extremely sensitive to fleas and may still be having an allergic reaction while using a “bite to die” flea product. In this case, we may recommend using two types of products including one that repels fleas. This decision should be made with the guidance of a veterinarian to ensure that multiple products are safe for your pet.

Clinical Signs 
  • Pruritus
  • Redness 
  • Most affected areas: back half of the body, base of tail, perineum 
  • Symmetrical hair loss in cats 
  • May be seasonal 
  • No age predisposition
  • Any pet with this distribution that is not on flea prevention
  • If clinical signs continue, and all other causes are ruled out, a secondary flea prevention may be recommended
  • Flea prevention 
  • Environmental flea control 
  • Flea control for other pets in household 
  • May require additional treatment to resolve secondary infection and get itchiness under control. 

Food Allergy 

Food allergy is the least common of the three types of allergies. It also manifests through signs of skin disease in our pets. It can also cause gastrointestinal upset, but the most common sign is redness, itchiness and secondary skin infections. Pets are most commonly allergic to proteins. It is extremely rare for pets to be allergic to grains, and we do not recommend grain free diets for this reason among many others. Pets can develop food allergy at any age and can develop an allergy to a certain type of food after eating it for several years. Commercial allergy testing kits are not reliable and should not be used to make a diagnosis of food allergy. The mainstay of diagnosing food allergy is with a food elimination trial. 

Clinical Signs 
  • Pruritus 
  • Redness 
  • Commonly affected areas: Ears, face and legs, belly, under the tail. 
  • Inconsistently causes vomiting, diarrhea, flatulence, increased bowel movements 
  • No seasonality 
  • Can occur at any age 
  • Diet elimination trial- The only way to diagnose food allergy is to feed either a novel protein or hydrolyzed protein diet for 12 weeks. The food should have only one protein source. We recommend a veterinary diet as OTC diets may be contaminated with the allergen. During this time there can be no treats or outside food as this will impact the results of the trial! 
  • Diet change, feeding ONLY prescribed diet with no outside treats! 
  • May require additional treatment initially to control itchiness or secondary infection. 

As you can see there are many similarities between these types of allergies! There are a few distinctions they can help guide your veterinarian in the right direction. Regardless, diagnosing and controlling allergies can be a lengthy and difficult process, remember a food trial takes 3 months! Not to mention, there are many other causes of an itchy pet that we did not discuss in this article. If your pet is shaking their head, chewing their paws, rubbing or scratching, we recommend a consultation with your veterinarian. Let your veterinarian walk you through their plan to get to the bottom of your pet’s issue and bring relief. There are many different factors that could be causing your pet’s skin disease. Dr. Chris Franklin is happy to be serving Louisville and Prospect, Kentucky here at Dogwood Veterinary Clinic. If you believe your pet is suffering from allergies, please give Dogwood Veterinary Clinic a call at (502) 710-0170 or request an appointment through our website here to set up a consultation with Dr. Chris Franklin!