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Home > Cats > Can Cats Be Allergic to Other Cats? (Vet Answer)

Can Cats Be Allergic to Other Cats? (Vet Answer)

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Dr. Rachel Ellison

DVM, Veterinarian

The information is current and up-to-date in accordance with the latest veterinarian research.

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Has your cat started sneezing, itching, or scratching lately? Maybe they’ve been grooming or biting themselves incessantly? There could be various causes of these behaviors, but one common, yet surprising cause is that cats can have allergies!  Some pet owners may ask, “Can cats be allergic to other cats?” The short answer is no.

Doctor Meagan Painter, a board-certified veterinary dermatologist says that it’s “Not something we have been able to demonstrate and/or not something we test for.”

But cats do have many other proven allergies. So, what are they? Read on to find out more!


Allergies and Feline Atopic Syndrome (FAS)

An allergy is a condition in which the body’s immune system goes into overdrive in response to a particular substance, called an antigen. The body essentially becomes hypersensitive to this antigen that it labels as foreign and releases histamine. This can cause a chain reaction and several side effects seen in an allergic response, such as itching and inflammation.

Feline Atopic Syndrome (FAS) is a newer, more general term used to describe allergic disorders in cats that affect the skin, gastrointestinal tract, and/or respiratory system.  Under this umbrella term, there are various allergic diseases which include flea allergy dermatitis (FAD), feline atopic skin disease (FASS), feline food allergy (FFA), and feline asthma. Below, we’ll delve a little bit more into each of these diseases individually.

1. Flea Allergy Dermatitis in Cats (FAD)

Flea allergy dermatitis occurs when a cat has a hypersensitivity reaction to proteins in flea saliva. Ctenocephalides felis, also known as the “cat flea”, is the most common flea species responsible for flea bites and causing flea allergy dermatitis in both cats and dogs. Non-allergic animals can have occasional scratching due to fleas, but those with an allergy will exhibit a much greater response. In fact, in cats that have an allergic reaction to flea saliva, sometimes even only a single flea bite can cause the cat to have an extreme reaction.

Often, signs seen in flea allergy dermatitis in cats can include an itchy, inflamed body, chewing, licking, and hair loss. These signs are often concentrated in areas along the head, neck, underside of the belly, and lower back half of the body. Small pimple-like bumps with crusting (called miliary dermatitis) are very common, and red ulcers or plaques can also occur. Upon examination, one may be able to see fleas or their excrement (called flea dirt) as evidence, but that may not always be the case.

Sometimes, a diagnosis is simply based on history, the lesions seen on the exam, and a good response to flea treatment and control. Allergy skin or blood testing may be an option, but it is not always foolproof and may be interpreted better when considered together with positive clinical signs.

Treatment is multifaceted; medications will be needed to provide the affected cat relief in the scratch-itch cycle as well as to control fleas (both on the pet and in the environment) to prevent future problems from occurring. Medical therapy with antihistamines may be helpful in a small percentage of cases, but treatment is most often successful with corticosteroids. Secondary skin infections, if present, will also need to be treated.

There are numerous options for flea control for the affected pet as well as any other pets in the household. Some of these options include spot-on treatments, oral medications, collars, and sprays. Your veterinarian will be able to discuss various options and help you determine what may be best for you and your pets’ situation. Environmental control will also be essential and should occur wherever the cat spends their time, whether inside (such as beds, furniture, carpet, etc.) and/or outside.

grooming cat using flea comb
Image By: Simone Hogan, Shutterstock

2. Feline Food Allergy (FFA)

Feline food allergy occurs in cats when hypersensitivity occurs due to a product in the food that they eat. The main sign seen is itchiness of the body, which often concentrates around the head and neck and that occurs consistently across all seasons1. In response to the itch, self-trauma is likely to result. Hives, crusts, thick or inflamed skin, and hair loss can all occur. Sometimes, a secondary bacterial or yeast infection will also be present. In addition to the skin signs, there may also be GI signs such as vomiting, diarrhea, a lack of appetite, or weight loss.

In cats, some of the most common food allergens include fish, beef, and chicken.  Surprisingly, a cat could develop an allergy to a food that they have already been eating for a long period of time. Unfortunately, there is no simple test to determine if a cat has a food allergy and the only way to diagnose this is to do a strict food trial.

A food trial should be done for at least 8 weeks with a new food, and typically would consist of either a novel protein diet or a hydrolyzed diet.  A novel protein (e.g., duck) and carbohydrate (e.g., potato) diet could be selected as long as the cat has never been exposed to the ingredients before. Alternatively, a hydrolyzed diet is made up of a prescription pet food in which the protein is broken down so small that the body is not meant to recognize it as an allergen. During the food trial, no other foods, flavors or products must be eaten; this would include other pet food, human food, treats, chews, or things that are flavored such as medications, toothpaste, or toys.

If during the trial, the signs significantly improve or resolve, the next step is at the end of the food trial and reintroduce the previous food. If the allergy signs return within a 2-week period, this is then determined to be a positive response for a food allergy. Various food trials to pinpoint which ingredients are causing the allergy may need to be performed.

cat in christmas hat eating on perfect gray background
Image By: BestDeals, Shutterstock

3. Feline Atopic Skin Syndrome (FASS)

Feline atopic skin syndrome occurs in cats that are allergic to irritants in their environment which could include pollens, molds, dust mites, etc. These allergens could be consumed (eaten or inhaled) or absorbed on the skin’s surface. Signs seen in this disease can include the skin signs discussed with the diseases above such as itchiness, ulcers, or ulcerated plaques, and cats may scratch, lick or bite affected areas over and over. The areas most affected are often on the head or neck and typically first start in cats that are less than 5 years old. Other diseases can exacerbate or mimic this condition, such as various infections or fleas, so it’s important to rule out other causes, too. Intradermal allergy testing can be conducted, but because cat reactions may be less intense than those of dogs, they can be harder to interpret.

Without intervention, this disease is likely to get worse over time; treatment of the signs can drastically improve a pet’s quality of life and may need to be continued for the life of the pet. If possible, avoiding offending allergens would be ideal and if any secondary skin infections are present, those concurrent diseases will need appropriate treatment too.

Image By: Susan-Santa-Maria, Shutterstock

4. Feline Asthma

Asthma in cats is a lower airway disease with inflammation that results from breathing in what their body determines is an allergen. In turn, this can bring about a series of events that result in airway inflammation, swelling, and constriction. These inflamed airways often promote mucus production and decrease in size, which both lead to making it harder to breathe. Signs seen with feline asthma may include rapid and shallow breaths or having difficulty breathing, sometimes with an open mouth. Over time, an affected cat may develop wheezing, coughing, or exercise intolerance.

For diagnosis, a complete history coupled with clinical signs and a thorough physical exam will be needed. Often, X-rays may have evidence of changes that go along with asthma. Bronchoscopy (using a camera that is passed down to visualize the airways) and bronchiolar lavage allow for obtaining samples of or from the airway that can aid in diagnosis. Additionally, bloodwork, heartworm, and fecal tests can be used to provide more evidence for diagnosis or to rule out other causes of breathing difficulty in cats.

cat with asthma
Image By: RozochkaIvn, Shutterstock



While the current consensus of veterinary dermatologists is that cats cannot be allergic to other cats, that doesn’t mean that they don’t suffer from other allergies. In fact, some can even suffer from more than one at a time. To keep your cat as healthy and safe as possible, the most important thing one can do is pay close attention to their pet and get help when needed.

If your cat is suffering from signs of an allergy, a conversation with your pet’s veterinarian may provide much-needed relief for your feline friend!

Featured Image Credit: Opel_pw, Shutterstock

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