Solar Dermatitis in Pets

26 October, 2020
Solar dermatitis is the skin's reaction to excessive sunlight. This isn't just a human problem and can affect our pets, too.

Solar dermatitis in pets can happen easily. Just like with humans, spending time in the sun can be fun, but too much exposure can be unhealthy. Solar dermatitis is the skin’s reaction skin to excessive sunlight. In pets, the degree of dermatitis depends on the time of day, climate, location, amount of exposure, and skin color.

Animals, like people, enjoy getting sun. Although many animals can happily lay in the sun for a while and feel the warmth of the sun’s rays, their owners have the responsibility to keep them safe. With that being said, it’s important to understand the damage solar rays can cause in order to prevent it.

Why is too much sun harmful?

Before we take a look at the dangers, it’s important to note that sunbathing for short periods and at the right time of day can have health benefits for your pet. On the other hand, we must recognize that in addition to visible light, solar rays also contain infrared light and ultraviolet light (UV), which can be harmful.

UV rays damage keratinocytes, which cause sunburns on the skin.

A key fact to keep in mind is that the harmful effects of UV rays are cumulative. In other words, prolonged and repeated sun damage can result in progressively more serious issues.

Additionally, melanin, the pigment that determines the color of skin, can absorb up to 45% of UV rays. This can be helpful in preventing sun damage.

Dog hiding from solar rays.

Solar dermatitis can damage cells

It’s been proven that UV radiation causes oxidative damage to cell membranes, DNA mutations, and even alters structural protein synthesis. As a result, abnormal activation of skin cells and an inflammatory reaction occurs.

At first, the skin becomes bumpy and red, then later the damaged tissue turns into rough patches. If the skin is constantly damaged, lesions can form and lead to skin cancer, which can then spread to the lymph nodes.

How to recognize skin lesions

Unfortunately, solar dermatitis in pets can imitate other skin problems, like allergies or pyoderma. For this reason, skin lesions commonly go unnoticed and untreated until irreversible damage has been caused or skin cancer has developed.

It’s important to note that, although dogs and cats tend to lick injured areas, itching caused by solar dermatitis is relatively minimal, unlike allergic dermatitis. It’s also possible for your pet to suffer from both solar dermatitis and a skin allergy at the same time.

When your pet has dermatitis, white fur will become patchy and the skin underneath red and irritated. If your pet has both white and dark fur, the dark parts will look normal and the skin underneath won’t be affected. When you run your fingers over the animal’s coat, you’ll be able to feel different textures because the darker fur protects your pet’s skin from the sun.

Common places for skin lesions

Sun damage generally affects unpigmented areas with little to no hair, like the flank, stomach, groin, ears, and nose, although lesions can appear in other places. If your pet normally lays on one side, lesions will likely be worse on the exposed side.

Stages of sun damage in pets

The progression of sun damage on the skin occurs in the following:

  • The first signs of solar dermatitis appear as red, swollen lesions, which might be sensitive to the touch.
  • After repeated sunburns, hair follicles are damaged, resulting in folliculitis. Lesions can be minor if they’re only superficial, or severe if they are deep.
  • With chronic sun exposure, damaged skin becomes thick and scars. Skin will be itchy, flaky, scab over, and ooze pus. Bacterial infection or pyoderma is common at this stage.
  • Finally, sun-induced tumors, such as squamous cell carcinomas, cutaneous hemangiomas, and hemangiosarcomas can appear.

What animals are most at-risk?

Solar dermatitis is most common in pets that live in hot, sunny climates. However, animals that live in high altitudes or spend a lot of time outside can also be affected, even if they live in temperate climates.

Generally speaking, animals that suffer from illnesses or genetic defects that cause alopecia or fur to thin are most at-risk. This is the case for pets with fleas or fungal infections.

Pets with chronic skin conditions, such as atopic dermatitis, are also vulnerable. Also, recent surgery that leaves areas of the skin exposed due to surgical trimming can leave your pet vulnerable to sunburns if unprotected.

Dogs owners whose pets suffer from autoimmune diseases should carefully monitor their sun exposure due to the high risk of making existing conditions worse. Dog breeds with the highest sensitivity to sunburns include: Dogo Argentino, white Bulldogs, white Boxers, Dalmatians, Beagles, and Greyhounds.

Diagnosing solar dermatitis

Solar dermatitis is diagnosed by observing the pet’s clinical signs and ruling out other causes of dermatitis, such as fungal or bacterial infections.

Ultimately, taking a skin biopsy and doing a histopathologic tissue exam are the best tools in diagnosing solar dermatitis. A secondary bacterial infection may develop, so your vet might prescribe antibiotics for two to three weeks before taking the biopsy.

In these cases, it’s critical to provide your pet’s complete medical history, including the degree of sun exposure, distribution of the lesions, description of the lesions, and the response or lack of response to previous therapies.

It’s also important to indicate any current drug treatments (including glucocorticoids) that could affect the tissue exam. Be sure to request a complete description of the results and seek advice from a veterinary dermatologist.

Treatment

Without a doubt, the best treatment for solar dermatitis in pets is prevention. Pet owners need to understand the importance of preventing prolonged sun exposure from an early age. Furthermore, no oral or topical medication can replace the prevention of harmful sun exposure.

Recommendations

The main recommendation for preventing solar dermatitis in pets is to limit their exposure to the sun. Keep your pets inside from 9:00 AM to 3:00 PM. If sun exposure is unavoidable, you should apply high-SPF waterproof sunscreen to your pet’s coat.

Be sure to use products made for animals and not humans, as the latter contains zinc oxide and para-aminobenzoic acid (PABA), which can be toxic to animals when ingested. You can easily find sunscreen for dogs in pet supply stores.

There are no sunscreens specifically made for cats. Cat owners should never use sunscreens that contain octisalate or acetylsalicylate, an aspirin-like substance that is toxic if ingested.

Dog sun suits or even a t-shirt are better than nothing. You can cut leg holes to protect your pet’s belly and back. Unfortunately, its legs will still be vulnerable.

A sleeping dog.

As you can see, solar dermatitis in pets is difficult to diagnose and treat early. Because of this, prevention is the best way to prevent skin problems in your pets.