Many people believe their dog or cat has a food allergy.  They are constantly licking and scratching as though they are obsessed.  Itching can be caused by fungal infections, dry skin, boredom, liver disease, pain or anxiety, so it is important to rule out those causes with a trip to the vet first.  However, about 70 percent of chronic itching is from allergic reactions.  Allergies can be caused by a number of things – fleas, environmental irritants such as dust or pollen – as well as food.  Most allergies are environmental.  Suspect an environmental allergy first, especially if they have a seasonal component.  It is estimated that only 10 – 15% of allergic dogs suffer from food allergies. 

Some dogs with food allergies may have vomiting or diarrhea, or may have chronic ear infections.  Typically, the only symptom is non-seasonal itching.   You can have allergy tests performed to determine the specific substances that trigger an allergic reaction, but they are expensive and are not always accurate.  In fact, they often return both false positives and false negatives resulting in about 60% accuracy.  Some veterinarians even consider them useless.

A food elimination trial is the best way to determine if your pet has a food allergy.  In a food elimination trial, everything is eliminated from the diet except for a novel protein and a novel carbohydrate.  Novel means an ingredient that you pet has not been exposed to in the past.  You may need to look at the ingredient list of all the foods you have fed in the past, then list everything they have eaten.  Typically, recommended “novel” proteins include meats such as:

  • Kangaroo
  • Bison
  • Duck
  • Rabbit
  • Venison

Some “novel” carbohydrates can include:

  • Quinoa
  • Oats
  • Pumpkin
  • Barley
  • Chickpeas

Once you have identified a single new protein and new carbohydrate you are only going to feed those foods for eight to twelve weeks and continue it for a month after any skin irritation has cleared.  Elimination diets are extremely strict.  You can not give them anything else during the trial.  No treats, chews, table scraps, medications or toothpastes with added flavor, supplemental fatty acids, or treats used to hide medications such as peanut butter, pill pockets or sandwich meats.  Everything must be removed expect for the novel and novel carbohydrate. 

If your pet does have a food allergy, you should expect to see a significant reduction in itching (about 50%) during the trial.  Some pets may see resolution in about four weeks, others may take longer.  Cats may need up to 3 or 4 moths to see results. 

Once you have some results, you will begin what are called “diet challenges”.  This means you can add in another ingredient or reintroduce the old food.  If there is a recurrence of allergy symptoms, return to the elimination diet.  If there is no reaction, try adding in another ingredient.  By adding ingredients and watching for reactions, you can determine what are allergens and what are not.   

There really is no cure for a food allergy.   In addition, you pet can develop other allergies in the future.  However, by identifying the ingredients which cause the allergic reactions in your pet, you can manage the allergy and make your pet much more comfortable.