What Causes Allergies in Cats?

When determining what causes allergies in your cat, consider the symptoms and likelihood of each of the following. Diagnosing a specific allergy is often a process of elimination. There are four main types of allergies in cats.

Flea Allergies

All cats will scratch at a flea bite, but cats that are allergic to fleas experience more severe symptoms. They bite and scratch hard enough to break skin­­, leaving open sores or even removing patches of hair. These open wounds are susceptible to infection, compounding the initial problem. Cats experience flea allergy most often on the rump (top base of the tail area), head and neck.

Strict flea control, using topical flea treatments and thorough cleaning, is usually enough to treat this allergy. When those measures do not solve the problem, corticosteroid injections may be given to block allergic reactions and provide symptom relief.

Food Allergies

Cats may develop food allergies at any point in their lives, often in response to the food they eat most frequently. Symptoms of food allergy include severely itchy skin (often around the head and neck), respiratory distress and gastrointestinal upset. Food allergies usually develop in response to beef, chicken, seafood, corn, soy, dairy products or wheat gluten.

The best way to diagnose a food allergy is to place the cat on a strict hypoallergenic diet consisting of a new food for eight to 12 weeks. If allergy symptoms improve significantly, you're likely dealing with a food allergy. Once a safe diet is established, food testing (introducing other foods into the diet one at a time) will help pet owners determine which foods to avoid. Due to the nature of food allergy, it is a good idea to change a cat's diet periodically, once allergens are known.

Inhalant Allergies

This type of allergy is known as atopy, and occurs when a cat is allergic to an airborne particle. The most common allergens for cats are mold, mildew, dust mites and tree, grass and weed pollens. Atopy is usually marked by severe, generalized itching.

Minimize exposure to allergens by keeping cats indoors, cleaning their bedding regularly and using air filters. Allergy shots may be prescribed to treat the allergic reaction. Antihistamines can be used as a preventative measure. Products designed to relieve itching may help treat the symptom, but should be used in conjunction with more aggressive treatment methods.

Contact Allergies

Contact allergy is the least common type of allergy on this list. It is caused by contact with an allergen, such as wool, certain plants and medications. Contact dermatitis, which manifests in itchiness and obvious skin irritation, is a result of exposure to either an allergen or an irritant. The difference is important when diagnosing and treating dermatitis. An irritant, such as soap or another household chemical, will cause a similar reaction in most animals. An allergen triggers an immune response in a specific cat. As with food, contact allergies are often the result of a long period of sensitization to the particular substance.