I think my dog might have a food allergy, what’s the best way to find out?

Whilst true allergies are very rare, food intolerances are becoming more and more common in dogs today. Often owners will find that their dogs simply do better on certain diets and nutrient levels and their dog’s digestion and skin problems begin to improve over time.

Food allergies in dogs differ to intolerances in that they involve an immune response and cause much more severe reactions than intolerances; primarily intensely itchy skin and occasionally vomiting or acute diarrhoea. Food intolerances (or adverse food reactions) more often cause digestive problems like diarrhoea, looseness and excess gas and only occasional skin conditions.

However, there can be a number of other causes for skin conditions to develop, like environmental allergens, genetic predisposition and reduced immunity for example, so all these causes should be considered by you and your vet if your dog is suffering.  With skin conditions that don’t quickly clear, like recurrent ear problems, year round itchiness or repeated skin inflammations, looking at your dog’s food and considering a food intolerance is a good idea.

The best way to establish if your dog has a food intolerance or allergy is through a feeding trial. There are two versions of these to try; either an elimination or a novel food trial. Elimination diets exclude as many suspected ingredients as possible, so common culprits like wheat, beef, soya or dairy. Hypoallergenic or grain free diets will often exclude these ingredients but it is important to save the full composition of whichever you choose before trialing, in case the diet isn’t as effective as hoped. The next step if he is not improving, is to eliminate more suspect ingredients from the composition list or consider a novel food trial.

With a novel food trial, you feed ingredients your dog has never tried before, so for example a lamb and rice, salmon and sorghum or rabbit and potato diet. It’s possible to find suitable products in the pet shop or here at tails.com by excluding the ingredients your dog is familiar with. Otherwise, a homemade diet can work. However, the difficulty with a homemade recipe is ensuring that the diet is balanced with all essential nutrients, vitamins and minerals and that your dog is getting an appropriate amount to eat.

The trial diet needs to be followed for at least 8 weeks to allow it to work, and it’s important to remain strict on not feeding treats or additional food at all during this period so you can see definitively whether the trial is having the effect you hoped for.


If you find your dog is much healthier and symptoms are reduced on either type of feeding trial then there are two options; trying provocative testing, where you reintroduce the old food to see for sure whether the symptoms return.  Or alternatively, you could continue feeding the test diet and slowly introduce ingredients back in that you think your dog can cope with until you have a dietary solution that you are happy is keeping your dog healthy and doesn’t cause digestive or skin symptoms.

There are some quicker ways of testing for allergies, in particular blood, saliva and skin testing but these are often more accurate for determining environmental allergies rather than food allergies and can be an expensive route.

The vet can offer some help with the symptoms; pre and probiotics can improve digestion, antihistamines, steroids and even adding in additional essential fatty acids can help your dog with skin irritations and itchiness, but the symptoms can return at any point with these treatments. So, excluding the ingredients causing the reaction is the best longer term solution

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