What is Feline Eosinophilic Syndrome?

Eosinophils are white blood cells present in all organs and blood. In cats, they play a crucial role in skin inflammation and are involved in numerous feline-specific skin issues. Feline eosinophilic syndrome encompasses three common dermatological conditions typically associated with hypersensitivity, often triggered by flea bites, but occasionally linked to food or environmental allergies (atopy). The syndrome may also result from bacterial infections. Stress, by weakening the immune system, appears to be an additional trigger factor.

Young adult or middle-aged cats (1 to 6 years old) are most commonly affected. Additionally, anxious cats seem more susceptible.

Three Main Forms of the Syndrome

Feline eosinophilic syndrome manifests primarily in three ways. A cat can exhibit one or several of these forms simultaneously:

• Eosinophilic plaque: Raised, red (erythematous), erosive, or ulcerated skin plaques causing severe itching. Commonly located on the abdomen, inner thighs, and occasionally the temples.
• Eosinophilic granuloma: Linear, raised, firm, and sometimes swollen (edematous) lesions. Often found on the chin, back of the thighs, or within the mouth cavity, usually without causing discomfort.
• Indolent ulcer: Crater-like lesion on the upper lips, typically on one side but occasionally bilateral. These ulcers can rapidly enlarge but are typically painless.

Diagnosis

Diagnosis is based on clinical examination and lesion appearance. Cytology can identify eosinophils, neutrophils, and bacteria in cases of secondary infection. Blood tests often reveal elevated eosinophil counts. Biopsy provides definitive confirmation.

Treatment Options

The treatment aims to:

• Address infections: Secondary bacterial infections are treated with oral antibiotics for 2 to 4 weeks or a single long-acting antibiotic injection.
• Manage allergies: Underlying allergies must be controlled using antiparasitic treatments, hypoallergenic diets, or removing irritants (perfumed litter, diffusers).
• Use corticosteroids: These rapidly reduce itching and lesions. Treatment starts with high doses followed by gradual tapering.
• Consider cyclosporine for recurring cases: This immunomodulatory treatment offers effective, safer long-term control.
• Other options: Antihistamines may help certain cats. Resistant cases might benefit from omega-3 supplements or specific antibiotics.

Prognosis

The prognosis varies. Cases linked to well-managed allergies typically have a good outlook. However, cats requiring lifelong medication or not responding to treatments may have a guarded prognosis. Continuous, tailored care is essential to maintain their quality of life.