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Pet Food Allergies – Symptoms and Treatments


It is estimated that 10-20% of allergies in dogs are related to food ingredients. If your pet licks his feet, gets ear infections and scratches, you might need to consider whether he has food allergies.

What does a food allergy look like?

Pets with food allergies commonly lick  their feet and may have itching around the face, ears and bottom. They may just be generally itchy and may or may not have gastrointestinal signs like occasional vomiting and diarrhea. This type of allergy develops at around 1 year of age and is not associated with a diet change. When your pet develops a food allergy to something they have previously tolerated, the immune system overreacts to an ingredient in the food, leading to itchy skin.

What are some other reasons for allergies?

There are of course other things that your dog can be allergic to. Flea allergies are common, as are contact allergies to plants such as Wandering Jew or grasses and of course atopic dermatitis is a common allergy. Pets with allergies often react to multiple things, so food can be a part of the picture but not necessarily the whole story. If your dog has allergies, consider using flea tablets in case a flea bite allergy is part of the problem.

Food allergies vs food intolerances

Food allergies tend to result in itchy skin, while a food intolerance tends to lead to vomiting and diarrhea or weight loss in our pets. There are whole careers made in distinguishing between the different types of allergies and intolerances that occur, so it is beyond the scope of our discussion here. The truth is no one knows what causes these allergies to develop. Our focus is on helping our pets cope with allergies until we solve the mystery.


There is no blood test to diagnose a food allergy. Your pet needs to undergo an elimination diet to rule out a food allergy. Before doing an elimination diet it is important to rule out a flea allergy, contact allergy and any infection that may complicate things.  Your vet can help you with this.

Elimination diets

There are two ways to do an elimination diet, either home-cook or use a prescription food. The prescription foods are easier to use and more balanced than home cooking, but only work in around 70% of cases of food allergies.  When doing an elimination diet you should avoid treats, snacks and even watch out for flea and worming treatments that may contain additives that trigger the food allergy. Some examples of prescription diets for food allergy trials include Hills Z/d, Royal Canin Hypoallergenic and Eukanuba Fish and Potato.

Home cooking

To do your own home-cooked diet trial you need to feed a novel protein diet. You can formulate your own based on a type of meat your dog has never had before combined with a carbohydrate source. Some examples are venison, rabbit or any other unusual meat.

Check the food your pet is currently eating and you will most likely see it contains chicken, but our pets also commonly eat beef, lamb and pork products too. So you need a meat protein that they have not previously been exposed to and one that is human grade and not full of sulphur preservatives. Once you’ve found your meat source, simply combine it with a carbohydrate like sweet potato, potato or rice.

How long to do the diet trial

The food trial must be done for 8-12 weeks. Some dogs take the whole 8 weeks to show any improvement in their allergies. If you have an accidental mistake (even if your dog eats something off the side of the footpath or out of the bin), you need to start all over again and continue another 8 weeks at least.

What to do after the trial

At the end of your diet trial reintroduce the old food again. This rechallenge stage is incredibly important to confirm that your pet really does have a food allergy, rather than coincidentally improving. Many pets fluctuate seasonally with their allergies and in some cases they may have a pollen allergy AND a food allergy, so the rechallenge can determine whether the food really helped or just seemed to.

If within a week to two weeks the itching returns during the rechallenge phase, you should be pretty sure that the food allergy is real. You can then chat to your vet or a nutritionist about how to formulate a food based on a novel protein that is balanced for long-term use.

What to avoid during a food trial

  • Treats.
  • Chews like rawhides, pig’s ears, dental chews.
  • Medications with flavouring (some antibiotics, wormers and flea treatments contain liver, beef or chicken).
  • Watch access to neighbour’s food, the cats food or other pets.
  • Toys with flavourings added.
  • Foraging on walks (some pets need to be walked with a basket muzzle to avoid eating things off the ground while you aren’t watching). You may need to avoid off-leash time for a while.
  • Faeces especially cat poo!
  • Human foods dropped while eating or cooking.

What next?

If you are pretty sure your pet has a food allergy, don’t forget to chat to your vet about whether there are any skin infections, fleas, mites or other complicating factors that may mean a food trial isn’t indicated. Pets that have inflamed, broken and red skin may have a secondary fungal or bacterial infection that needs treatment or they won’t respond to the diet change.

When you do a food trial you want to do it once and do it well, so make sure you have the time and space to focus on doing it right. There is no point in doing a food trial when you know your friend is visiting and they won’t be able to resist feeding your dog treats under the table!

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