Food Allergy in Cats

Food allergy is the third most common skin allergy in the cat, after flea bite allergy and atopic allergy. The most common symptom of this allergy is itchy skin, but between 10-15 per cent of cases will also have gastrointestinal symptoms, such as diarrhoea and vomiting. Food allergy can affect cats of any age and it can even occur in a cat that has been on the same diet for years! If food allergy is expected, most cats are initially treated with hypoallergenic diets and symptomatic treatments to prevent infection and irritation. This article will give you information on the signs and symptoms on food allergy, as well as the steps to take in identifying and treating this in cats. 

The most visible signs of food allergy are:

  • Persistent scratching
  • Skin lesions
  • Loss of hair
  • General deterioration of the coat

These symptoms do not develop overnight, they tend to become more obvious and intensify over periods of time, months or even longer.

If your cat is itching, the typical area where food allergy will affect them is on the skin around the head and neck. You may find small, pale, fluid filled lumps on your cat’s skin. The lesions themselves do not pose a significant health hazard, but the continuous scratching can cause secondary skin wounds and bacterial infection. Gastrointestinal problems can also lead to further problems such as health compromising weight loss from food avoidance.

If these signs appear your cat should receive veterinary care as soon as possible. After other potential causes of the skin lesions are ruled out (these could also be caused by flea bites), food allergy is likely the cause of the clinical signs. If a food allergy is suspected the specific allergen should be identified and removed from the cat’s diet – this is easier said than done.

The most commonly used protein sources in cat food include beef, pork, lamb, chicken, turkey and eggs. Because protein is essential in a cat’s diet the new diet must contain a protein the cat has not been previously exposed to, such as venison, kangaroo or fish.

Since the same holds true for carbohydrates, the vegetables frequently used in cat foods like wheat, barley and corn should be replaced by something similar to potato or rice. Your cat should consume this new diet and water for a period of 6-10 weeks. It is likely that the allergic signs will gradually disappear. In that case we can assume that the allergen was a component of the previous diet.

To identify the allergen the owner reintroduces components of the cat’s original diet one by one and watch for any symptoms to reoccur – if they do reoccur these will probably show within a week or two. With a lot of effort and patience the allergens may be identified this way. There is also the option of using a commercial hypoallergenic diet such as Hill’s Z/D.

If you notice these signs of discomfort in your cat, make sure to visit your vet as soon as possible. This will prevent further problems from occurring as a result of the food allergy.