Solar Dermatitis in Cats

What is solar dermatitis?

Solar dermatitis is a skin disease caused by exposure to the sun. It occurs mainly in cats with white or pale patches of skin (non-pigmented areas).

While any breed of cat can be affected, it is more common in young adults and white-haired cats with blue eyes that spend a lot of time outside.

What are the signs of solar dermatitis?

Solar dermatitis often starts as skin redness (erythema) and excessive dryness (resembling a sunburn). As it progresses, the skin becomes crusted (scabby) and ulcerated. Sometimes, it may progress to a malignant tumor called a squamous cell carcinoma at the site.

The most commonly affected areas in cats are the ears, but the nose and the eyelids are sometimes involved. The lesions appear to cause irritation and the cat may shake its head or scratch its ears, causing bleeding from the ear margins or tips.

How is solar dermatitis treated?

Treatment can vary, depending on the severity of the condition. Topical steroid creams, or oral steroid medications, are sometimes used to prevent discomfort and reddening. Other topical or oral medications, such as imiquimod (an immune stimulant), may also be used.

How can I prevent the condition from worsening?

Keep your cat out of sunlight, ideally by keeping them indoors between the hours of 10:00 am and 4:00 pm on sunny days, because this is when ultraviolet (UV) light is most intense. If it is not possible to stay indoors, or if your house has many windows where your cat likes to spend time, apply sunscreen to the affected and thinly-haired areas. Unfortunately, many cats will quickly lick the sunscreen off. Some products may be toxic to cats, so never use a human sunscreen without first checking with your veterinarian.

How do I know if my cat has squamous cell carcinoma?

If there is any concern that the condition may be progressing to squamous cell carcinoma, your veterinarian will recommend taking a tissue biopsy from the affected area (a surgical excision of a piece of the tumor). Most cats need general anesthesia for this procedure. That sample is then examined by a veterinary pathologist under a microscope, a process called histopathology. Histopathology helps to make a diagnosis and can indicate how the tumor is likely to behave.