What Is Flea Allergy Dermatitis in Cats? Symptoms, Causes, and How To Treat It

What Is Flea Allergy Dermatitis in Cats?

Fleas are blood-sucking insects that are a major cause of itching (pruritus) in cats and that can also transmit diseases such as plague (caused by Yersinia pestis) and cat scratch fever (caused by Bartonella henselae).

Fleas can also transmit tapeworms. Additionally, massive flea infestations can cause significant blood loss and anemia. 

Fleas can cause intense pruritis in cats who develop an allergy—or hypersensitivity—to proteins found in flea saliva. Cats are exposed to these proteins when fleas bite them. This condition is known as flea allergy dermatitis (FAD).  

FAD is the most common skin disease in cats, especially in the southern United States, where the environment is more favorable for fleas. This condition is a major reason pet parents seek veterinary care for their cat.

Flea allergy dermatitis in cats can affect any age, breed, or gender.

Although flea allergy dermatitis in cats is not a medical emergency, the condition may require urgent care if left untreated because secondary skin lesions and infections often develop. 

Symptoms of Flea Allergy Dermatitis in Cats

The most common symptoms associated with flea allergy dermatitis in cats are itching, scratching, and excessive grooming.

Other signs in cats may include:

• Visualizing fleas and/or flea dirt (flea feces); however, the absence of fleas doesn’t rule out FAD because itchy cats are typically good groomers

• Hair loss, often on the neck, ear base, tail base, groin, and symmetrically along the back

• Crusts, scabs, or irritated skin

• Tapeworms, typically witnessed as short, “rice-like” segments around the anus

Causes of Flea Allergy Dermatitis in Cats

Flea allergy dermatitis in cats is a hypersensitivity reaction that occurs when the cat’s immune system overreacts to proteins found in flea saliva.

It’s important to note that cats with underlying allergies are more likely to become affected by FAD than those without allergies.

How Veterinarians Diagnose Flea Allergy Dermatitis in Cats

To diagnose flea allergy dermatitis in cats, a veterinarian will first perform a thorough physical examination, looking for evidence of fleas, flea dirt, and skin lesions.

A flea comb may be used to check for flea dirt.

Since other skin diseases often mimic signs caused by flea allergy dermatitis in cats, additional diagnostics may be recommended, such as:

• Skin impression—Skin and hair are collected and observed under the microscope looking for evidence of bacterial and fungal (yeast) infection.

• Skin scraping—Skin and hair are collected through a “scraping” technique to look for evidence of skin mites.

• Fungal culture—Hair is obtained to look for evidence of fungal (ringworm) infection.

Blood work may be performed to ensure your cat is otherwise healthy and to help guide treatment planning.

Treatment of Flea Allergy Dermatitis in Cats

Since flea allergy dermatitis in cats is caused by flea bites, treatment consists of treating, or killing, current fleas and preventing future flea infestations.

You must treat the affected cat, as well as all other pets in the home, with a veterinary-approved flea preventive.

Cats are sensitive to many chemicals, such as permethrin, that are found in pesticides and flea killers, so consult your veterinarian for the best product for your cat.

Examples of veterinary-approved products include:

• Revolution® or Revolution Plus®

• Credelio™

• Comfortis™

• Capstar®

• Bravecto® Plus

• NexGard® Combo

• Advantage™ II

• Advantage Multi™

• Frontline® Plus

• Cheristin™

Each product has unique advantages and disadvantages.

Some products start killing fleas within 30 minutes and others within 12 hours; some are applied topically, and others by mouth; some are contraindicated in certain situations; some can be purchased over the counter while others require a prescription.

Consult your veterinarian about the best product for your cat.   

In addition to treating the primary problem, your veterinarian may prescribe medications needed to treat secondary skin infections.

Potential treatments include oral antibiotics, such as:

• Clavamox®

• Simplicef®

• Cephalexin

• Convenia® (injectable)

These may be used with topical agents, such as medicated shampoos and leave-in conditioners or mousses.  Oral or injectable steroids may also be recommended to help control itching. 

Recovery and Management of Flea Allergy Dermatitis in Cats

Fleas are prevalent and hardy, so year-round control is important for cats with flea allergy dermatitis.

Flea allergy dermatitis in cats can be effectively managed, but it may recur, especially without proper prevention and flea control.

A recovery cone or recovery suit may be helpful to prevent skin lesions caused by overgrooming. 

Managing the environment and preventing future flea infestations is important when managing flea allergy dermatitis in cats.

Recommendations include:

• Washing your cat’s bedding in hot, soapy water

• Cleaning all surfaces

• Vacuuming frequently to help remove flea eggs and flea dirt (i.e. sources of food for developing fleas)

• Disposing of vacuum debris in a sealed outdoor trash bin

• Treating your home with a pet-safe flea product that includes an insect growth regulator (IGR)

• Consulting a pest control company to treat your yard for fleas

Diatomaceous earth and borax are natural options that can be used to help with flea infestations.

Select a product that is safe for use around cats and always follow the manufacturer’s guidelines.

Prevention of Flea Allergy Dermatitis in Cats

Preventing fleas completely isn’t possible. However, monthly year-round flea control is vital to ensure the well-being of a cat with FAD.

Prevention of flea allergy dermatitis in cats is much easier and more cost-effective than treating an infestation in your home. 

If your cat starts itching and scratching, have them examined by the vet right away.

Check your cat frequently for fleas with a flea comb, and bathe them often with a calming oatmeal shampoo to lessen your cat’s itching and immune response.