Ah, the sunny days of summer are here--time for dogs to take long walks and play Frisbee at the park or beach and for cats to sunbathe on the windowsill. Before stepping out to enjoy the summer weather, you should protect your pet as well as yourself from the harmful effects of too much sun.

Sunlight is healthy for pets as it is for people; sunlight helps the skin produce vitamin D, which protects the skin and helps balance the bodyￔￇￖs calcium levels and metabolism. However, too much of anything can be harmful, and too much ultraviolet (UV) radiation can cause sunburn, or solar dermatitis, in cats and dogs.

According to Dr. Karen Campbell, veterinary dermatologist at the University of Illinois Veterinary Teaching Hospital in Urbana, sunburn starts as redness and hair loss on the ear tips, bridge of the nose, or abdomen and can lead to skin ulceration, infection, and carcinoma. Excessive sun exposure can also exacerbate existing skin problems.

Certain breeds of cats and dogs may be predisposed to sunburn. "White cats are those that most commonly get sunburn, usually on the tips of the ears," explains Dr. Campbell. "Cats don't need to be outdoors to get sunburn; the UV radiation can pass through windows."

Sunburn is also common in pale and short-haired dogs, usually on the bridge of the nose, the abdomen, groin, and insides of the legs. "The belly is prone to sunburn because of sunlight that reflects up from the sidewalk. Similarly, dogs that spend a lot of time at beaches can get sunburn from sun reflecting up from the hot sand," says Dr. Campbell.

Sunburn and repeated, excessive exposure to UV radiation can lead to skin cancer, particularly squamous cell carcinoma, in dogs and cats as it does in humans. Therefore, breeds that are predisposed to cancer, such as boxers and Weimaraners, need extra protection from the sun.

Sunburn can also cause skin ulceration, leaving the skin susceptible to opportunistic bacterial, fungal, and parasitic infections. Sun exposure may also exacerbate autoimmune skin diseases in which the immune system attacks skin cells, such as pemphigus and lupus. As the sun damages the skin, skin cells die and can release proteins that inappropriately trigger the immune system.

To protect pets from sunburn and its consequences, Dr. Campbell recommends applying sunblock on the small susceptible areas of skin, such as the bridge of the nose and the ear tips. You can also apply a line of sunblock along any part in the fur along the head or back. For cats, sunblock is usually sufficient.

For dogs, sunblock is usually not effective on the abdomen, since it can rub off in tall grass, wash off at the beach, or be easily licked off by the dog or its playmates. "There are spandex-type bodysuits on the market designed to block UV radiation," says Dr. Campbell. "I highly recommend these for dogs who spend a lot of time outside, especially dogs who visit the beach."

Although the idea of bringing a bodysuit-clad dog to the park or beach may sound ridiculous or embarrassing, it may be the most effective and important sun protection you can provide for your pet. Dr. Campbell explains that doggie bodysuits are common at some beaches, and "it doesn't look ridiculous if all the other dogs are wearing one."

For more information about solar dermatitis in pets, contact your local veterinarian