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Common allergies in cats: Four things you can do about them

allergies in cats
(Image credit: Getty Images)

Allergies in cats are different to allergies in humans or dogs. Vets often like to remind pet parents that ‘cats are not small dogs’ – and it’s never truer than in allergies! Cat allergies have different symptoms, different causes, and different treatments to allergies in dogs. Feline allergies are less well known and less well studied than dog allergies, but they’re very common causes of itching and poor skin in cats. We’re going to look at the common allergies in cats, and what you and your vet can do to help.

1. Flea Allergic Dermatitis – or ‘flea allergy’ in cats

The most common allergy in cats is flea allergy, or ‘flea allergic dermatitis’, which causes about a third of all skin problems in cats. As the name suggests, this is an allergy to fleas or – more correctly – to the proteins in flea saliva. Cats with flea allergies often don’t have visible fleas-  they groom too much to make it likely that you’ll see one – but they only need to be bitten once to have a huge reaction. Their skin may go bumpy, they may lose fur, or they may scratch to the point of making themselves bleed.

What you and your vet can do to help flea allergies

Since flea allergic dermatitis is the most common allergy, if your cat has signs of an allergy it’s likely your vet will recommend treating for flea allergy just in case. Flea allergy in cats is a hypersensitivity to the saliva of the flea, so a cat needs to be bitten in order to react. Preventing them from being bitten is important. First, your vet will recommend a flea preventative for your cat. Your cat will need to take this year-round. 

The best product for fleas depends on your living situation and your area, so talk to your vet to find a good product for your cat. All other animals in the house will need to have good flea prevention too so that fleas can’t survive on them, you can find more advice in our article, six ways to prevent fleas. In the face of a current infestation, hiring a professional exterminator to kill any fleas, eggs, or larvae living in the house is a good idea. In severe cases of allergic reaction to fleas in cats, your cat may need anti-inflammatories (usually in the form of steroids) or antibiotics to control any secondary skin infections.

2. Feline Atopic Dermatitis – or ‘environmental allergies’ in cats

The second most common allergy in cats is feline atopy, although the correct term is ‘non-flea, non-food hypersensitivity dermatitis’. This is an allergy to things in the environment, such as pollen, weeds, trees, or insects. Cats suffering with pollen allergies are generally itchy, especially around their ears. They may have a rash, bumps on their skin, or hair loss. Cats with pollen allergies may also sneeze or have watery eyes. There’s also a link between allergies and asthma in cats.

What you and your vet can do to help feline atopy

Your vet can only diagnose atopy once the other allergic causes have been ruled out, so be patient. Many cats with allergic dermatitis need medications to help control their symptoms. Steroids, anti-inflammatories, skin supplements, and antibiotics may all be recommended. Shampoos are sometimes useful, but cats aren’t easy to bathe! You can also help your cat by not letting them outside on high-pollen days, or by installing air filters to reduce the pollen in the house. 

Since many cat allergies are to house mites, keeping on top of hoovering and washing of bedding is useful. Storage mites thrive in the dust at the bottom of large food bags, so buying smaller bags, or freezing portions, can help. You could also transition your cat to a wet food diet to reduce the chance of them coming into contact with storage mites.

3. Food allergies in cats

The third most common allergy in cats is an allergy to food, although they’re much rarer than the previous two causes of allergies in cats. Food allergies make up 1-5% of cats with skin disease. However, they’re rewarding to diagnose because they can be much more easily managed than allergies to pollen. 

Cats with food allergies often have severe itching of the head and neck. Just like the other allergies, they may have hair loss and bumps or rashes. They often also have gastric upset, including soft stools. The most common foods for cats to be allergic to are beef, chicken, and fish, which are very often found in feline diets.

What you and your vet can do to help food allergies in cats

Diagnosing a food allergy in cats is theoretically simple: they need to be fed a hypoallergenic diet for 6-8 weeks. Then, if symptoms improve, the old diet should be introduced – a flare-up of symptoms proves the allergy. However, for the 6-8 weeks, your cat needs to be fed no tidbits at all, which may mean keeping them inside so they can’t eat elsewhere. 

They also need to be fed on a truly hypoallergenic diet – either a hydrolyzed diet or a home-cooked novel protein diet. Unfortunately, switching to foods containing different proteins to the one they’re normally on often doesn’t work, as these foods may contain traces of lots of different animal proteins, which are enough to trigger an allergic response and confuse the results. Your vet will be able to recommend a diet for you to feed your cat to see if they’re allergic. 

Luckily, if your cat does turn out to be allergic to their food, all you have to do is feed them a diet that doesn’t contain the same animal proteins. Treats and tidbits will also need to be restricted to proteins they’re not allergic to.

4. Mosquito-bite hypersensitivity and allergies in cats

The last type of allergies in cats is to mosquito bites. Mosquito bite hypersensitivity is more commonly seen in outdoor cats, and only generally in areas where there are lots of mosquitos. It can look similar to flea allergic dermatitis, and though rare, is worth considering in cats that are not responding to flea treatment and whose flare-ups are sporadic. The head and ears are the most commonly affected areas – you’ll notice itching, and may even see bites on your cat’s ears and the bridge of their nose.

What you and your vet can do to help mosquito allergies in cats

It’s best to try to prevent your cat from being bitten by mosquitos – keeping them indoors tends to reduce exposure. Mosquito repellents are useful, but should only be used under the supervision of a vet, as many of the chemicals are harmful to cats. 

Allergies in cats: A round-up

If your cat is showing signs of an allergy, chances are it’s an allergy to fleas. Pollen allergies are less common, and food allergies are less common again. Allergies in cats can be difficult, but talking to your vet about your feline friend’s allergies is the first step in getting to the bottom of that bothersome itch!