Sometimes we find that we do not follow our own advice when it comes to pet care. I (Dr. Perry Jameson) was reminded of this last weekend when I was home and saw our dog Flipper lying in the grass in full sunlight. He looked like he was sunbathing!
This worried me as I had warned countless pet owners of the dangers of sun exposure and here I was exposing my own dog. Just as is the case for human skin, the sun can damage the DNA of dog and cat skin. This damage can result in similar problems, too.
Squamous cell carcinoma is the major concern for sun-exposed cats. Patients with this cancer present with crusting lesions usually on the nose and ears, but it can occur anyplace where there is little hair or pigment. The lack of pigment makes white-haired and light-haired cats more prone.
Outdoor cats are more likely to get the amount of sun required to cause the DNA damage resulting in cancer. However, indoor cats who like to bask in the sun coming through windows also have been documented to develop squamous cell carcinoma.
Crusting lesions, nonhealing sores and masses on the face and ears are early signs of squamous cell carcinoma. If noted, your veterinarian can take a small sample to submit to a pathologist to determine if it is cancer.
Dr. Michelle Wall, a veterinary oncologist, stressed to me that early detection is important. If caught at an early stage, a cure is possible. However, if the tumor cells are allowed to grow, they will begin to invade deeper into the underlying tissues.
Even when invasive, the cancer does not routinely spread (metastasize) to other locations, but getting the disease under control locally still is hard.
Aggressive surgery is the best treatment. This means removing the outer portion of the ear or front portion of the nose. Fortunately, cats do not look at themselves in the mirror, so they tolerate these procedures well. For tumors that cannot be completely removed, radiation therapy can be used to control the remaining cancer.
Cutaneous hemangiosarcoma is the major cancer associated with sun exposure in dogs. As with cats, white and lightly pigmented dogs that stay outdoors are more prone to develop the disease.
The abdomen and groin region are the most common locations, as they are hairless in most breeds, allowing the sun to reach the skin.
The same factor that determines prognosis for cats applies to dogs. If the tumor is located in the superficial layers, surgical removal may be a cure. However, if it is in the deeper portion of the skin, the prognosis changes.
These tumors are more aggressive, and here they differ from cat skin cancer in that they may spread elsewhere. The spleen, liver, heart and lungs are common locations. Once tumors spread, dogs usually die within 12 to 18 months.
Early tumors will look like red, purple or even black dots. They may be flat or raised. Initially, the tumor may look like a bug bite. If you see something that concerns you, have it checked out and biopsied.
Veterinary dermatologist Dr. Lisa Akucewich says dogs and cats also can develop sunburn just as humans can. The sun exposure also may worsen existing skin conditions, such as allergies or hot spots.
Akucewich warned that it takes only 30-60 minutes of sun exposure a day to suffer enough DNA damage that could result in cancer. The best prevention is avoidance.
The sun's rays are strongest 10 a.m.-5 p.m., so keep pets indoors during these hours. If they must be outside, keep them in a shaded area or use protective clothing. Fluppies.com and designerdogwear.com are two companies that make sunsuits (start around $35).
Sunscreen also can be applied to the ears, nose, skin around lips, abdomen and groin regions. Pets often will ingest the sunscreen, so keep that in mind.
There are some suncreens available that have been developed specifically for pets. Doggles has one available for cats and dogs ($10), while Epi-Pet Skin Care has a formula for dogs only ($18). To work well, it needs to be applied liberally and every four to six hours.
Products that are safe for human babies are usually safe for pets, too. Look for those that are fragrance-free, nonstaining and provide UVA and UVB protection. Do not use anything containing octyl salicylate in cats and avoid zinc for cats and dogs.
An ounce of prevention
The frustrating thing is that once the DNA damage occurs, even if they never get exposed to sunlight again, they are prone to developing cancer.
So I will be checking Flipper monthly for any unusual lumps or changes in skin color. In the sunny months of the year, I am going to keep him inside during the day, too.
Dr. Henri Bianucci and Dr. Perry Jameson are with Veterinary Specialty Care LLC. Send questions to firstname.lastname@example.org.
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