Solar Dermatitis in Cats

Solar dermatitis is sometimes mistakenly referred to as “sun allergy”. Common sites of dermatitis in cats include ears, lips, nose, belly, or areas where hair loss has occurred. Typical presentation of feline solar dermatitis is a red, scaly patch of skin in an area that is not well protected by hair. Solar dermatitis is not usually itchy. If sun exposure continues, the disruption to the skin intensifies to raised, firm, wrinkly patches, erosions, ulcers or crusts, and hair loss. Secondary bacterial infections are quite common, requiring antibiotics to resolve. If left untreated, patches of solar dermatitis can become cancerous. Possible cancers include squamous cell carcinoma and hemangiosarcoma.

Outdoor cats with white fur, outdoor hairless cats, or outdoor cats with hair loss due to allergies, surgical scars, radiation or other causes are most at risk for feline solar dermatitis.

Long term exposure to high energy ultraviolet light (UVB) causes feline solar dermatitis. Prolonged exposure of skin to UVB damages skin cells and causes the dilation of blood vessels at the skin’s surface. Epithelial structure damage causes inflammation,which increases tissue damage. To try and repair the damage, skin cells proliferate, which can result in a precancerous or cancerous state.

Diagnosis by a veterinarian is required to distinguish feline solar dermatitis from other skin diseases with similar appearance, such as discoid lupus erythematosus (an autoimmune skin condition). Physical examination and consideration of the cat’s breed, hair type and skin characteristics help rule out other potential causes of symptoms. Skin biopsy and histology are required to definitively diagnose solar dermatitis. If dermatitis progresses and becomes cancerous, additional diagnostics are required to confirm and guide treatment.

Feline dermatitis treatment includes:

• Limiting sun exposure
• Treating inflammation with topical steroids and Vitamin A
• Controlling secondary bacterial infection with antibiotics
• Surgical removal of precancers or cancers The effects of solar dermatitis can last for weeks or sometimes months. Damage to skin cells cannot be reversed, so new cells must be produced in order for the skin to heal. If detected early, limiting sun exposure and the application of topical steroids and/or Vitamin A is helpful in managing the condition. Antibiotics are indicated in cases where bacterial infection occurs. If precancerous or cancerous cells develop, surgery can be curative. The prognosis of skin cancer depends on the type of cancer, its development pattern, and whether it has spread to other sites in the body (metastasized).

Limiting sun exposure helps prevent solar dermatitis. Confining outdoor cats with thin or white fur or with exposed patches of skin during the middle of the day limits exposure. UV protective pet wear is available. Sunscreen for cats may be effective though the product requires liberal application and regular re-application during sun exposure. Note: cats are sensitive to many toxins, and most human-grade sunscreen is not advised for veterinary use. Always consult a veterinarian before using human sunscreen on animals.

Feline solar dermatitis is fairly common in cats with thin, patchy or white fur.

• Reduced sun exposure
• Topical steroids and Vitamin A
• Antibiotics
• Surgery