Food allergies in dogs

dog on white background


Just like people, dogs can be allergic to something in their food. This often causes skin and/or tummy problems.

Food allergies can develop at any stage in a dog’s life but most commonly start when a dog is less than a year old.

A food allergy can’t be cured but symptoms can be avoided by limiting your dog’s diet and not allowing them to eat the foods they are allergic to.

Most allergic dogs with a food allergy live a normal life if problem foods are avoided.

What is a food allergy?

A food allergy is when a dog’s immune system overreacts to one or more of the ingredients in their diet. Symptoms usually include skin problems (allergic skin disease) and/or tummy problems (such as diarrhoea and vomiting).

Dogs tend to be allergic to proteins (meat or dairy). They can be allergic to any protein they have ever eaten, most commonly to ingredients used regularly in dog food such as beef, chicken or lamb. Some dogs will be allergic to other ingredients, such as wheat.


Skin problems and tummy problems are the most common symptoms of a food allergy.

When to contact your vet

Make an appointment with your vet if you notice any of the symptoms above or you think your dog may have a food allergy. There are many other conditions that can cause these symptoms as well as a food allergy.

You know your dog best. If they don’t have the symptoms listed above but you are still concerned it’s always best to contact your vet.


If a food allergy is well managed, your dog can live a perfectly normal life. Left untreated, food allergies can have a serious effect on your dog’s health and quality of life.

How will food allergies affect my dog?

If a food allergy is well managed, your dog can live a perfectly normal life. Left untreated, food allergies can have a serious effect on your dog’s health and quality of life.

Diagnosis of a food allergy

Food trial - the best way to diagnose a food allergy is a ‘food trial’. This involves:

  • Feeding a veterinary diet with special ingredients that your dog won’t react to. Your vet will recommend which diet to feed.
  • You will need to feed the special diet and nothing else (other than water) for as long as your vet advises – usually 8-12 weeks. No human food or dog treats (not even dental sticks!)
  • If your dog’s symptoms get better during the trial, it confirms that they were reacting to something in their food.
  • If you allow your dog to eat anything else during the food trial they might react to it and you won’t know if the special diet has been working or not.
  • Your vet or vet nurse can give you some tips on how to make treats out of the special food so that you can still give your dog some variety.


If your dog is diagnosed with a food allergy, treatment options include:

Feed a special diet for life

Feed them a diet that doesn’t trigger their allergy (and nothing else) for life.

Try to find out what they are allergic to

Once your dog is settled without symptoms on a special diet, your vet may recommend adding ingredients back into their food (one at a time) to try and find out what they are allergic to.

If your dog doesn’t show any symptoms, this is a ‘safe’ food. If your dog’s symptoms come back after eating a certain food, it’s likely they are allergic to it. This will help you select a dog food that only contains safe foods.

Food trials and exclusion diets can be tricky and take a lot of time, the alternative is to keep feeding your dog a special veterinary diet for life.

Some dogs with a food allergy will also have allergies to things in the environment, this may cause allergic skin disease (atopy). In this case, they might improve a bit on a special diet but they may need some other treatments as well to help keep their skin symptoms controlled.

Referral to a skin specialist

Your vet might recommend your dog is seen by a skin specialist. They will be able to perform more advanced tests and give you more information.

Ongoing care

To stop your dog having symptoms you will need to make sure they only eat food that contains “safe” ingredients. Dogs with food allergies can to a perfectly normal life if they are fed a diet that suits them.

In extreme cases, it is sometimes necessary to muzzle dogs when they are on walks to stop them accidentally eating something that isn’t allowed.


There is nothing owners can do to prevent a food allergy. Spotting the signs early will help you get your dog back to normal as soon as possible.

Published: October 2018

Support PDSA

All of our work helping the UK's pets – including this article – is funded entirely by public support.

If you've found our information useful please donate today. This will ensure we can continue to help pet owners and their sick pets for many years to come.

PetWise Pet Health Hub – brought to you thanks to support from players of People’s Postcode Lottery 

Written by vets and vet nurses. This advice is for UK pets only.

Illustrations by Samantha Elmhurst