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Food Allergy

Adverse reactions to substances within the diet, known as a food allergy, cause year-round itchy (pruritic) skin, with all the resultant signs that may entail.

Protein sources such as beef, lamb, chicken and dairy products are the most common to cause problems, but anything that your dog eats on a regular basis can become an allergen.

Remember that the body develops an allergic response after repeated exposure to an allergen common in their environment.

It is also worth remembering that most commercial dog foods contain pork and chicken additives, no matter what flavour is stated on the packaging, and so simply changing brands will not help.

Reactions can occur at any age, but when onset is within dogs younger than 6 months, or older than 6 years of age, food allergy is the more likely cause of allergy present.

Itchiness is non-seasonal, as your dog eats the allergen all year round, and the degree of itch can be mild to severe.

Itching generally leads to self-trauma, with scratching and chewing leading to areas of hair loss, scabs and secondary infections with bacteria or yeasts. Recurring ear infections are commonly seen due to irritation leading to increased wax production within the ear canals and resultant infection.

A small percentage of animals may also develop gastrointestinal signs such as vomiting or diarrhoea.


The only accurate way to diagnose a food allergy is by a strictly controlled food trial

-      A novel protein, or proteins commercially broken down (hydrolysed)to an unrecognizable size are fed exclusively.

-      This is performed by either preparing a home-cooked diet containing a protein your dog has never eaten before and a specially chosen carbohydrate, such as boiled potatoes, or by feeding a prescription hypoallergenic diet from Acorn.

-      The food trial is continued for 8-10 weeks, with NO other foods given. No treats, chews, milk or even chewable heartworm prevention medication (discuss alternatives with our vets) should be given during this period.

Remember that even a single mouthful of an allergen can lead to a marked reaction, just as with a person with a peanut allergy, so strict adherence is VITAL for the trial to be diagnostic.

In dogs with secondary infections and severe pruritis, we will generally treat these concurrently with the trial.

Clinical improvement is suggestive of the diagnosis, but to check, your dog should be challenged with the old diet. An immediate return of itching confirms food allergy.


Food allergy, once diagnosed, is easy to treat, by merely preventing the offending allergen from inclusion in the diet. Relapses in dogs that steal the wrong foods are commonly seen.

At Acorn we stock Wellness diets, composed of novel proteins, which are ideal for long-term maintenance in many of these dogs. These are available over the counter and are more cost effective and palatable than many prescription diets. We still advise prescription or home-cooked protocols for the diagnostic trial however.

Prognosis is excellent, but everyone in contact with your dog must be educated in which foods to avoid. It can also be harder to combat in households with small children who may drop food or sneak it under the table at dinnertime!