Dogs can get overheated just like we do, but they do not know when to stop and cool off and cannot tell you when they need a drink or to cool down. You have to be the one to make these decisions for them. With some dogs, you may notice that the sun, not just the heat, is causing your dog serious discomfort. Solar dermatitis is a commonly diagnosed problem in people, and is starting to be recognized in animals as well. This is a condition characterized by lesions or sores in areas that are exposed to the sun. For example, dogs with short-haired coats are susceptible, especially on the head, ears, face, abdomen, and flank. Although it may seem like just a simple sunburn, solar dermatitis can quickly turn into actinic keratosis, or skin cancer if exposure is not stopped.

Sun allergy (solar dermatitis) in dogs causes skin irritation in any part of the skin exposed to sunlight on a regular basis. This condition is similar to a bad sunburn in people, and can have the same damaging results (skin cancer) if not treated and protected. Dogs most often affected are those with white or light colored fur and light skin like Bull Terriers, Boxers, and Bulldogs. This condition can also cause dermal fibrosis, cysts, and bacterial infections. The signs of sun allergy are redness, sores, scales, wrinkles, bald spots, and thickened skin in spots.

Symptoms of sun allergies vary, depending on the amount of sun and the length of time your dog’s skin was exposed before the damage was treated.

Some dogs are more susceptible than others, such as:

It is the ultraviolet (UV) radiation in sunlight that causes the sun allergy, which is why it mostly affects dogs with light skin and fur. Dogs with short-haired coats are  very susceptible; solar dermatitis can quickly turn into actinic keratosis, or skin cancer.

Since sun allergy presents itself similar to so many other skin disorders, it may be difficult to determine the definite cause. The most unique symptom of this disorder that makes it stand out from other ailments is that the skin damage is only on the areas that are exposed to the sun, such as the ears, nose, head, neck, back, flank, and abdomen. Be sure to let your veterinarian know if your dog spends a lot of time outdoors and provide a medical history including previous illnesses and injuries as well as abnormal behavior. Your veterinarian will examine your dog’s body from head to toe, which includes skin and coat condition, breath sounds, pulse rate, blood pressure, body temperature, weight, and height. Some of the tests needed are a urinalysis, fecal examination, blood chemistry profile, glucose levels, and a complete blood count (CBC). 

The veterinarian may also take a skin scraping to sample in order to rule out bacterial or fungal infection. Since sun damage sometimes leads to skin cancer, a skin biopsy will be taken from each of the most affected areas. This involves taking a small scraping of the skin similar to the sample taken for infections. The sample will be analyzed under a microscope to look for cancerous cells. Radiographs (x-rays) will also be done to determine if there are any internal damage or tumors. In some cases, the veterinarian will also order an MRI, CT scan, or ultrasound for a more detailed look.

The most important part of treatment is keeping your dog out of the sun. The veterinarian may prescribe glucocorticoids for allergies to the sun and early sun damage. Oral retinoids (a synthetic form of vitamin A) may also be recommended, but there are side effects that may occur so regular monitoring of your dog’s health will be needed. 

If the damage has already become cancerous, treatment will include surgically removing the cancer, nearby lymph nodes, and detailed testing of the nearby organs (such as the brain, liver, heart, and kidneys). Chemotherapy and radiation treatments may be necessary as well to make sure the cancer has been eradicated.

It is essential to stop the sun exposure as much as you can by keeping your dog inside during the day. If it is necessary for your dog to go out in the sun, a waterproof sunscreen for babies can be used, or your veterinarian may give you a recommendation. Dog t-shirts are also helpful in controlling exposure to the sun and there are many types of sun suits on the market that are specially made for dogs.

Recovery depends on whether your dog’s sun damage caused cancer and whether it is treatable or not. If the veterinarian is able to remove all of the cancer, your dog can live for another three or four years with no sun exposure. Be sure to bring your dog back in for testing at least once per year to make sure the cancer has not returned.