by Suzanne Morris, DVM

Spring means allergy flare-ups for most kitties’ human servants. Cats can also get allergies that commonly affect their gastrointestinal tract, respiratory tract, ears, and skin. One such skin allergy involves fleas, ectoparasites that feed on a host (kitty’s) blood, which involves the flea biting the host’s skin. Flea allergy dermatitis (FAD) is the most common dermatitis allergy affecting cats in geographies with flea populations.  The host’s allergy is a hypersensitivity reaction to components of the flea’s saliva.

Cats can sometimes also develop skin lesions that contain eosinophils, a type of white blood cells that responds to the presence of parasites. These types of lesions are often plaques or ulcerations than can appear anywhere on the skin surface (those that affect the lips are referred to as rodent ulcers).

Common signs indicating that a kitty may have a flea bite allergy would be skin lesions (often small scabs or crusts) found over the back near the tail and/or around the head. Most flea host animals do not have skin lesions from flea exposure—these typically develop in the presence of an allergy. Evidence of fleas (flea feces and/or the fleas themselves) further support a diagnosis of flea allergy. Additionally, evidence of tapeworms can provide evidence of flea exposure (as cats develop tapeworms through flea ingestion). Intradermal allergy testing can be done (usually with a dermatologist).  And finally, a kitty’s response to effective/consistent flea preventative can help determine whether the skin lesions are the result of a flea allergy.

Depending upon the severity of the clinical signs, treatments such as antihistamines or steroids may be recommended by your veterinarian to keep itchy kitties more comfortable and decrease their skin scratching.


White A. Flea Allergy Dermatitis. VIN Feline Associate. (2017, accessed 12 Mar 2019).