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 that are non-pigmented areas.
The most commonly affected areas in the cat are the ears, but the nose and the eyelids are sometimes involved. In the early stages of solar dermatitis, the skin may look pink and scaly with some hair loss. As the condition progresses, the area becomes crusted and ulcerated. The lesions appear to cause irritation and the cat may shake its head or scratch at the ears, causing bleeding from the ear margins or tips. Sometimes the condition progresses, and a malignant tumor called a squamous cell carcinoma develops at the site.
"The most commonly affected areas in the cat are the ears, but the nose and the eyelids are sometimes involved."
What can be done to prevent the condition from worsening?
Sunlight should be avoided. This is best achieved by keeping the cat indoors between the hours of 10:00 am and 4:00 pm on sunny days. If this is not possible or if you live in a house with a lot of windows and your cat likes to sun herself in the windows, sun block should be applied on the affected and thinly-haired areas. Unfortunately, many cats will rapidly lick the sunscreen off. Since some products may be toxic to cats, never use a human sunscreen preparation without first checking with your veterinarian.
How will I know if my cat has squamous cell carcinoma?
Your veterinarian will recommend taking a tissue biopsy from the affected area if there is any concern that the condition may be progressing to squamous cell carcinoma. Most cats will need general anesthesia in order for your veterinarian to perform this procedure.
A biopsy is a surgical excision of a piece of the tumor. Pieces of the tumor are then examined by a veterinary pathologist under the microscope. This is called histopathology. Histopathology is not only helpful to make a diagnosis but can indicate how the tumor is likely to behave. For more information, see handout “Squamous Cell Carcinoma in Cats.”