Over the last few weeks, there’s been much talk about the impact of severe summer heat on pets. Dogs, in particular, are prone to heat stroke, with multiple preventable fatalities happening every year. An awareness of the risk, combined with simple steps to keep dogs cool, will save many lives.
There’s a second aspect of summer weather that has received less coverage: the impact of too much sunlight on the skin.
We all know about the risk of too much sun for humans: ultraviolet rays can damage the DNA of the melanin-producing cells in our skin, leading to the development of malignant melanoma, a challenging type of skin cancer.
We know that we need to keep an eye on our own skin, protecting ourselves from too much sun and looking out for moles that change in character, or new areas of pigmentation.
When I was concerned about a small skin lesion on my own leg recently (which turned out to be harmless), the first question the dermatologist asked was: “Have you ever suffered from blistering sunburn”. To prevent melanomas, avoiding this type of over-exposure to strong sunlight is key.
Dogs and cats also suffer from malignant melanoma, but interestingly, this is not linked to sunlight, and very rarely develops on the skin. Instead, it’s seen as black growths in the oral cavity (on the gums), on the toes, or inside the eye. It’s a difficult cancer to tackle, but keeping pets out of the sun won’t help prevent it.
This does not mean that it’s safe to let all pets out in strong sunshine: there’s a different type of skin cancer that can develop in pets, prompted by too much sunlight. This malignant skin cancer is called squamous cell carcinoma. It’s a condition that is almost exclusively seen in cats with white noses and white ears.
Most dogs and cats have natural protection against this cancer and are not at risk. Their fur and the pigment in their skin (which gives them brown, black and ginger-colored fur), protects them by filtering out the dangerous, cancer-causing ultraviolet radiation from sunlight.
In contrast, white cats have no pigment in their skin to protect them. The fur on their ear tips and noses is so thin that these areas receive the full blast of ultraviolet radiation in the form of sunlight if they spend time outside on sunny days.
The disease process starts with simple sunburn. Owners of these cats notice that their ears (and sometimes nose tips) look red, sore and sometimes blistered, especially after sunny days. The reddened areas often settle down, but repeated bots of sunburn then commonly progressed to skin cancer after months or years.
The problem is that the cancer can be so malignant that treatment is very challenging: if the cancer has become well-established, even after the most radical surgery, it tends to recur.
Squamous cell carcinoma is so common in white cats that if a cat develops sunburn of the ear tips, many vets will recommend immediate amputation of the upper parts of the ear.
If this is done early, the chance of a malignant, potentially fatal cancer developing is minimised. An earless cat appears odd at first, but cats are not vain about their appearance, and owners soon get used to the new look of their pets.
Similarly, if the tip of the nose is burnt, or develops reddened areas with scabs, there is a high risk that this could develop into cancer. Again, radical surgery to remove the tip of the nose is recommended.
Affected cats do look strange, with a flatter face, and more open breathing holes compared to a normal cat with a nose. But they are healthy, and they will live longer lives than those that do not have such radical treatment.
Obviously, it’s better to prevent squamous cell carcinoma from developing on the ears and nose in the first place. To do this, you need to reduce the amount of ultraviolet radiation from sunlight reaching the skin cells.
The best way to do this is by regularly applying sunblock whenever the sun is shining. If you have a white cat (or any cat with white ears and/or nose), you should apply sunblock to their nose and ears every morning during the summer months: make it part of your daily routine. If you apply the block at the same time as you are giving your cat breakfast, they will associate the procedure with the reward of food, which should make it easier.
Ideally, you should use a sunblock designed for pets, but these are not always easily obtained, so human products may be used instead.
When you apply anything to a cat’s body, they tend to lick it off, or use their paw to rub the area, and then lick their paws. For this reason, you need to use a sunblock that is safe, bland and non-irritant: high-factor products designed for human babies are generally used. Use a water-resistant cream, which will last longer and may be more resistant to the cat trying to rub it off.
As well as protecting cats outdoors, remember that normal glass (eg 4mm thick) allows 86% of ultraviolet light to pass through it, so consider special transparent UV-blocking film to apply to windows in areas overlooking your cat’s favorite sleeping spots.
White dogs that enjoy sunbathing lying on their backs can also benefit from regular sunblock application. Cancer is not a risk, but they can still suffer from sunburn, so simple protection from this discomfort makes sense.