QUARTERLY BEAT / OCTOBER 2025
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THE ANSWERS YOU REALLY WANT TO KNOW ABOUT FELINE ATOPIC SKIN SYNDROME
Joya Griffin, DVM, DACVD Animal Dermatology Clinic, Louisville, KY
Still scratching your head over feline allergic skin disease? In this VETgirl Webinar, “The Answers You Really Want to Know About Feline Atopic Skin Syndrome” Dr. Joya Griffin, DACVD, reviews our updated understanding of feline atopic skin syndrome (FASS), from reaction patterns and diagnostic challenges, to evidence-based treatment approaches. Missed the webinar? Watch the replay HERE or check out the highlights below! that are less commonly seen in dogs. They can have lesions as subtle as erythema and seborrhea or present with classic pustules. Other signs of infection include crusted papules, eroded to ulcerated plaques, and linear to nodular granulomatous lesions that may be ulcerated. Because these presentations are similar in appearance to the reaction patterns that occur in allergic cats, secondary staphylococcal infections may go overlooked. A fungal dysbiosis was found in the skin of allergic cats in one study with Malassezia being isolated in higher numbers in affected sites pointing toward the importance of looking for and treating secondary infections in cats that present with skin disease. The exact pathomechanism of FASS remains unclear, however, histopathologic studies show similar inflammatory reactions as found in the canine patient. T cell involvement is apparent but whether IL-31 is a key pruritogenic cytokine remains unclear. Cats with allergic skin disease, whether related to food, fleas or environmental allergens, present with varying reaction patterns. FASS can also been seen in conjunction with allergic asthma, conjunctivitis, and rhinitis in some cases. The cutaneous reaction patterns in the cat include head and neck pruritus (or lesion-less pruritus), eosinophilic granuloma complex, self-induced hair loss (“fur-mowing”), papulocrustous dermatitis (“miliary dermatitis”). These reaction patterns do not indicate a specific hypersensitivity disorder. They can be seen alone or in various combinations in the same cat and can present differently from season to season or as allergy symptoms worsen over time. For example, one year the cat may have an indolent ulcer as a reaction pattern due to pollen allergen andthe following year may erupt with miliary dermatitis. These reaction patterns can also occur in non-hypersensitivity diseases as well as atopic dermatitis, food hypersensitivity, insect hypersensitivity, adverse cutaneous drug reaction, contact hypersensitivity, and intestinal parasite hypersensitivity.
Far less is known about allergic skin disease in cats compared to dogs and humans. Feline patients often present differently, with variable clinical signs, inconsistent demonstration of IgE, and with limited knowledge regarding their skin barrier function. There is debate as to whether atopic dermatitis (AD) even exists in the cat. For years, the term non-flea, non-food hypersensitivity dermatitis (NFNFHD) was the preferred term and more recently the term feline atopic skin syndrome (FASS) is often favored. FASS is one component of the broader feline atopic syndrome (FAS) which encompasses a spectrum of hypersensitivity disorders with varying presentations that affect the skin, gastrointestinal and respiratory tracts. Whatever the terminology chosen, little is known about allergic dermatitis in cats relative to their canine counterparts. In one retrospective study, NFNFHD was found in 12% of allergic cats. The face and ventrum were most commonly affected and allergen-specific IgE was detected in almost 70% of these cats suggesting an allergic component. But overall, few studies exist.
Common facial (left) and ventral abdominal (right) presentations of feline allergic dermatitis (Photos courtesy of Dr. Joya Griffin, DACVD) Likewise, little is known about the microbiota of allergic cats. Secondary bacterial infections are reported in less than 50% of cases which is less common than reported in dogs. This may be due to decreased corneocyte adherence of bacteria, though more recent studies show higher prevalence of infections. Cats with bacterial infections may present in varying ways
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