Flea allergy in cats

There are many reasons why cat's itch and allergic dermatitis or skin allergies can be the source of irritation. In the allergic state, a cat's immune system "overreacts" to foreign substances called allergens or antigens. There are four known types of allergies in cats: contact, flea, food and inhalant.  This article discusses flea allergy, common reactions and how to treat this condition. 

What is meant by the term "flea allergy"?

A normal cat experiences minor skin irritation in response to flea bites. Even in the presence of dozens of fleas, there will be a small amount of itching. On the other hand, a cat with flea allergies has a severe, reaction to flea bites. This occurs because the cat develops an allergic response to the flea's saliva. When the cat is bitten, flea saliva is deposited in the skin. Just one bite causes intense itching.

What does this reaction do to a cat?

The cat's response to the intense itching is to chew, lick, or scratch. This causes hair loss and can lead to open sores or scabs on the skin, allowing a secondary bacterial infection to begin. The area most commonly involved is over the rump, just in front of the tail. This is probably because fleas find this part of the cat more desirable.

What is the treatment for flea allergy dermatitis?

The most important treatment for flea allergies is to control and prevent flea bites. Strict flea control is the backbone of successful treatment. There are many products available for flea control, and in some cases, multiple products may be needed. Some are used on the cat and some in the cat's environment. Fortunately, with today's modern and highly efficacious flea preventives, flea control is achievable by all cat owners.

Corticosteroids ("cortisone" or "steroids") can be used to block the allergic reaction and give immediate relief. This is often a necessary part of dealing with flea allergy. Some cats respond best to long-acting injections and others to oral medication. Cats are much more resistant to the negative side-effects of steroids than humans and dogs, but significant side-effects can occur if they are not used properly. For this reason, the goal is to administer the smallest amount of steroid needed to keep the cat comfortable.

Some cats can be desensitised to the adverse effects of flea bites. Flea saliva extract (flea antigen) is injected into the cat in tiny amounts over a prolonged period of time. This is an attempt to reprogram the cat's immune system so it no longer over-reacts to flea bites. If successful, itching no longer occurs or is less intense when the cat is bitten. This approach is successful approximately 50-75% of the time.

If it isn't fleas, what else can cause a cat to itch?

  • Food intolerance/allergy
  • Housedust and pollen allergy (atopy)
  • Ear mites
  • Harvest mites
  • Insect bites
  • Skin bacterial infections