Food Allergies in Pets

Common symptoms and how you can help your pet


One of the most common allergies that occur in our pets is food allergy. In order to help your pet, you need to be able to recognise the typical triggers, symptoms and signs. However, since most of the symptoms can also be side effects of other diseases, you should always consult your veterinarian if you have concerns.

This is part of the Nutrition Guide for Dogs & Cats series.

What is a food allergy?

A food allergy describes an overreaction of the immune system to a particular food ingredient by producing antibodies against that ingredient. Most commonly, these are proteins. Particularly allergenic foods contain beef, chicken, lamb, and eggs as well as dairy products; for cats also fish and for dogs also soy can cause allergic reactions.

However, pets can also react to protein-containing foods like wheat, barley and rice; but these allergies are less common. A food allergy can develop over a prolonged period. In this respect, a dog or cat can enjoy its food for a long time without any symptoms. The immune system will react later. This delayed overreaction of the immune system manifests itself primarily with skin inflammation and itching.

Common signs of food allergy in pets

Skin inflammation

Due to the connection between the immune system and the skin, the latter becomes inflamed as a defence mechanism of the body. The emitted inflammatory substances trigger itching in the affected animal. The damaged skin can become infected by bacteria, which further increases itching.


Dogs generally have an itchy feeling and reaction in the face, on the ears, paws, under the armpits, in the groin area, on the stomach and around the anal area. Cats are particularly affected on the head and neck. The itching drives the animals to scratch, nibble, bite, excessively brush, and lick the affected areas. Animals will also try to relieve the itching by rubbing these areas of the body against the wall or other surfaces.

Other skin issues

The animal’s skin can also become dry and crusty. It can thicken and/or darken. Hair loss/bare patches (alopecia), secondary skin problems (inflammation/infection) due to constant scratching and/or licking, pustules, and hot spots (rather rare) can appear.

Gastrointestinal problem

Increased defecation, flatulence, diarrhoea, constipation, vomiting, and colon inflammation can occur.

Ear and paw infections (dogs)

The inflammation can severely affect animals, either because the auditory canals swell severely, or the paws are so inflamed that pustules and discharge of pus develop.

Eye problems (cats)

Inflammation, eye discharge, tear duct blockage and conjunctivitis can arise.

Most of these examples can have other causes so it is important to discuss your concerns with a veterinarian. Once these causes or diseases have been ruled out, it is reasonable to assume that your pet has a food allergy.

First Steps When Your Pet Has a Food Allergy

  • Determine the allergy trigger: It is important to first identify the trigger for the allergy to help your pet. A special and highly effective method is the exclusion or elimination diet. Over a period of several weeks, the affected animal only receives food that it did not eat before. For this method, it is crucial to be extremely strict and constant in controlling and monitoring any food intake your pet has during this period. If the symptoms recede, you will be able to identify which food components are the trigger for the allergy.
  • Treat the food allergy correctly: As soon as the triggering food or ingredient in the food has been identified, your pet should not be given this food in the future. Nowadays, there are several tasty, hypoallergenic foods on the market which can help with your pet’s diet. Your veterinarian can advise you on the best choice for your pet based on the individual test results. Another option is to prepare a homemade diet. But this should only be done under close veterinary supervision to avoid nutrient deficiencies or excesses, and other health problems.
  • Accompanying treatment and medication: Your veterinarian can prescribe specific medication for your pet to control the itching caused by the allergy and, if necessary, antibiotics or other medicines against secondary infections. Medical shampoos may be recommended to relieve itchy and inflamed skin. While these treatments will help with your pet's symptoms, the best treatment is still to identify and prevent the cause of the food allergy in the first place.

Allergies are different from intolerance 

There is a significant difference between allergies and intolerance regarding the immune system. In the case of an allergy, the immune system reacts by producing antibodiesIn the case of intolerance, the immune system is not activatedHere, the body is missing specific enzymes to digest the fooda well-known example is lactose intolerance in cats. 


See More guides for pet owners



Food Allergies in Dogs. vca_corporate. [accessed 2021 Oct 22].
Food Allergies. Cornell University College of Veterinary Medicine. 2017 Oct 16 [accessed 2021 Oct 22].
Food Allergies in Pets: Signs, Diagnosis, and Treatment | 
VetDERM Clinic. :: VETDERM CLINIC. 2021 [accessed 2021 Oct 21].
How to Recognize and Treat Food Allergies in Pets. 
FirstVet. [accessed 2021 Oct 25]. Watson TDG. Diet and Skin Disease in Dogs and Cats. The Journal of Nutrition. 1998;128(12):2783S-2789S. doi:10.1093/jn/128.12.2783S
Allergies & Skin Issues in Pets | Oregon Veterinary Medical Association. [accessed 2021 Oct 25]. Team CN. What every pet owner should know about food allergies. Clinical Nutrition Service at Cummings School. 2017 [accessed 2021 Oct 25]. Futtermittel-Allergie - [accessed 2021 Oct 21].
llergien bei Hund und Katze. [accessed 2021 Oct 25]. Kissingen L| B. FAQ FuttermittelallergieLABOKLIN Bad Kissingen. [accessed 2021 Oct 25].
Futtermittelallergie. Dr. Christine Löwenstein. [accessed 2021 Oct 25]. 

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