All about cat allergies

You may be reading this article as you’ve noticed your cat seems itchy. There are many diseases that can lead to itchy skin in cats, with itchy cats often being diagnosed with allergic conditions. Cats, just like people, can suffer from allergies to a range of things; commonly, flea allergies, food allergies or an allergy to something in the environment (e.g. pollen, grass, house dust mites, etc.). This page aims to help you understand cat allergies and how to manage it. 

In humans, we usually associate allergies with respiratory symptoms like sneezing and a runny nose. Cats can also present these signs, although dermatological symptoms are much more common. Signs include:

In cats, allergies are distributed into 6 clinical presentations:

The response of the immune system 

Allergies in cats occur when the immune system overreacts to a normally harmless substance, called an allergen, mistakenly identifying it as a threat.  

To eliminate this perceived danger, the immune system releases various inflammatory substances. These chemicals increase blood flow to the skin (causing redness or erythema), alter local tissue function, and stimulate nerve endings—leading to itching, which is the hallmark sign of allergic disease and often worsens other symptoms. 

Unlike in humans, histamine is not the primary inflammatory mediator in cats. This is why antihistamines are generally less effective for feline allergies than they are for people. However, they may still be helpful for mild cases or as part of a broader treatment plan. 

Common allergens in cats

Depending on the type of allergen that the cat is sensitive to, we can divide allergies into three groups:

It's important to point out that, just like humans, not all allergic cats are sensitive to the same allergens! Each allergic cat has its own allergic profile, which appears to be determined by its genetic susceptibility to allergic disease and its interaction with the environment.

However, cats who do suffer from one type of allergy seem to be predisposed to other types as well.

Which cats can suffer from allergies?

Any cat may develop allergies; however, Abyssinian cats appear to be predisposed. In most cases, the first clinical signs are observed within the first three years of life, although cats of any age may be affected. 

Exclusion of other diseases

Allergies are associated with a range of skin symptoms and lesions, but the most common sign of allergic disease is itchy skin. However, besides allergies, there are other skin diseases that can cause/enhance itchiness, such as:

This means that to diagnose a cat as allergic, your veterinarian will need to conduct some tests to rule out other diseases that can cause similar symptoms first.

Staying on top of parasite control

Updating your cat’s external parasite treatment can help veterinarians figure out if your cat suffers from flea allergy dermatitis. Over time, fleas can become resistant to certain treatments, which is why your veterinarian may ask you to change the product that you are using.

Starting a food trial

To figure out if it’s something in your cat’s diet that is causing its symptoms, your veterinarian will likely recommend a dietary exclusion trial. This trial consists of providing your cat with a strict new diet for 8 to 12 weeks, and during this time, that’s the only thing it’ll be able to eat! It’s vital that this diet is fed exclusively in order for a food trial to be effective; this can be more challenging for cats that are known hunters, so do discuss this with your veterinarian.

According to your cat's dietary background, your veterinarian may recommend:

If your cat improves during this trial, its normal food can be reintroduced to see if it triggers an allergy flare, thus confirming a food allergy. However, if there is no improvement during the trial, it’s more likely that your cat has atopic dermatitis.

Considering environmental allergens

To determine which environmental allergens your atopic cat is sensitive to, your veterinarian can perform blood tests (serological testing) and skin tests (intradermal testing).

Allergies are chronic diseases that require long-term management. Depending on the allergens involved in each case, treatment options can vary.   

Due to the complex nature of these diseases, multimodal approach is often recommended, which is a combination of the following options:  

Allergen avoidance

If your cat doesn’t have contact with the allergens it’s sensitive to, the immune system will not mount the allergic response that results in itchy skin and other skin lesions.   

Avoiding the offending allergens can usually be achieved in cats with flea allergy dermatitis by keeping their parasite treatments up to date. This also involves treating any other pets in the household, as well as the home environment. 

Food allergic cats also benefit from changing their diet to one that does not contain the offending allergens.  

However, allergen avoidance is not always possible in atopic cats due to the ubiquitous nature of environmental allergens. But you can still aim to reduce your cat’s exposure to triggering allergens, depending on which allergens your cat is sensitive to.

Topical products to bring ingredients where necessary

Prescription sprays and lotions containing steroids are often effective for managing allergic rashes. Non-drug topical options, such as DOUXO® S3 CALM, which contains 0,75% Ophytrium®, can also help. This product is designed to reduce irritation, soothe the skin, maintain hydration, and restore the skin’s barrier function. Additionally, it helps limit the adhesion of potentially harmful bacteria, such as Staphylococcus. 

Drugs to manage pruritus and inflammation

Given that itchy skin significantly impairs cats' welfare, itchiness relief is the mainstay of allergy management.   

There are several medications that can be used to reduce itchy skin, such as steroids, cyclosporine, and essential fatty acids. Your veterinarian will choose the best option for your furry friend.  

Desensitization treatment to address the cause

Immunotherapy, commonly known as allergy shots, can be used to manage the atopic cat. This treatment consists of giving increasing doses of the allergen the cat is sensitive to over a period of time, desensitising the cat´s immune system.   

The goal of immunotherapy is to re-programme the immune system, thus preventing allergy symptoms from developing every time the cat is exposed to the allergen. 

This treatment involves periodic vet visits over an extended period of time (months), and results take some time to be noted. 

Depending on your cat's personality and clinical signs, your vet will recommend which treatment options are most effective so that your cat can feel comfortable and itch-free again.