Nutritional management of food allergy in cats

Food allergy (dietary hypersensitivity) is an important cause of dermatological and gastrointestinal disease in cats. The true prevalence of food allergy is unknown, but it has been suggested to be the second (after flea allergic dermatitis) or third most common cutaneous hypersensitivity disorder and responsible for between 1 and 15% of pruritic dermatoses.

Up to 30-50% of cats with chronic non-specific diarrhoea may also have either food allergy or food sensitivity^1,2. Unfortunately differentiating a true allergic response (dermatological or GI) from an intolerance or sensitivity (i.e., non-immunologically mediated reaction) can be extremely hard.

COMMON CLINICAL SIGNS OF FOOD ALLERGY

Types I (immediate), III (immune-complex related), and IV (delayed) hypersensitivity disorders are thought to the major causes of food allergy, with perhaps type I being most important. Food allergy is caused by a reaction to proteins or glycoproteins in the food, and in cats the most commonly reported allergens are:

Cats with food allergy may also have other concurrent hypersensitivities such as flea allergic dermatitis and atopy. Reducing or eliminating the food allergy component can help to reduce the 'allergic threshold' and help manage the other conditions too.

DIAGNOSIS OF FOOD ALLERGY

The diagnosis of food allergy relies on a food elimination trial, ideally followed by recurring signs on re-introduction of the original diet.

A diet should be chosen containing restricted protein sources to which the cat is not likely to react (non-allergenic or only proteins to which the animal has not previously been exposed). The use of a hydrolysed protein diet is the most reliable way of reducing protein antigenicity in a diet and provides a superior confidence for an elimination trial than using a 'novel' protein diet³.

Data suggests that the majority of proteins inducing an allergic response are in the region of 20-80 kDa in size^4,5. Hydrolysis of proteins to smaller, low molecular weight fractions is a potent means of reducing the antigenicity of a diet. Importantly, hydrolysis also reduces the antigenicity through altering protein structures³.

MANAGEMENT OF THE FOOD ALLERGIC CAT

If a cat responds to feeding a hypoallergenic elimination diet then there are several options:

• Maintain the cat on the hypoallergenic diet, providing it is suitable for long-term feeding in the relevant life-stage (Feline HA is suitable for all life stages).
• Re-introduce elements of the original diet to try to identify (and avoid) specific allergen(s).
• Trial feeding of an alternative restricted antigen diet, which may be suitable so long as no reaction is found (e.g. Feline EN).

CLINICAL ADVANTAGES WITH THE USE OF FELINE HA

The protein hydrolysis used in Feline HA dramatically reduces antigenicity by producing lower molecular weight peptides and by disrupting antigenic determinants. Protein hydrolysis is the most reliable way to produce a "hypoallergenic diet". Furthermore, Feline HA provides:

• A highly restricted source of proteins, with a highly purified carbohydrate source.
• Enhanced essential fatty acid and vitamin E levels to help manage inflammation and enhance the cutaneous barrier.