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Why Do Dogs Lay in the Sun? (Vet Answer)

dalmatian dog basking in the sun

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Dr. Lindsay Bisset Photo

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Dr. Lindsay Bisset

The information is current and up-to-date in accordance with the latest veterinarian research.

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Most dogs love to spend time lying in the sun and seem to gravitate towards a sunny spot in the house or the garden. Have you ever wondered why dogs love to lay in the sun? Or whether it’s okay for your dog to spend time sunbathing?

While we can’t read their minds, we can assume that dogs sunbathe for the same reason that we do: laying in the sun feels good. Dogs seem to enjoy the warm, relaxing feeling of sunlight on their bodies. The sun’s warmth helps a dog heat up, stay warm on a cold day, and dry off when wet.

divider-dog paw

Benefits of Sunlight 

Exposure to sunlight helps regulate a dog’s circadian rhythm. Melatonin levels rise as it gets dark, signaling that it’s time for sleep, and are suppressed in response to light when it’s time for a dog to be awake.

There’s more to the circadian rhythm than just the sleep-wake cycle, though. A dog’s circadian rhythm controls other physiological processes such as energy metabolism. A healthy circadian rhythm is critical for good health.

In areas of the world with dark winters, some breeds of dogs develop a condition known as light-responsive alopecia or seasonal flank alopecia. Affected dogs lose patches of hair, typically on the flanks. The hair loss is often symmetrical. Typically, the disease follows a seasonal pattern. Affected dogs start losing hair in the fall, with regrowth occurring in the spring. The condition is not well understood, but it is thought to be caused by the lack of sunlight exposure to the pineal gland. Melatonin may help treat this condition.

Exposure to sunlight has another benefit: it is thought to increase the brain’s release of the mood-boosting hormone serotonin. Serotonin has many functions. It helps regulate moods and is responsible for feelings of well-being.

dog laying outside
Image Credit: ArtTower, Pixabay

Do Dogs Need Sunlight to Produce Vitamin D?

Vitamin D has been called “the sunshine vitamin,” but dogs, unlike people and many other animals, are not efficient at synthesizing vitamin D in their skin through sun exposure. For this reason, dogs are dependent on their diet to meet their vitamin D requirements and do not need to sunbathe to produce Vitamin D. Although this is the case, sunlight has other health benefits for dogs.

Too Much of a Good Thing

While sunbathing has health benefits, your dog can get too much sun exposure.

UV rays from the sun can cause sunburn, especially in areas where a dog’s coat is sparse, like the areas around the nose, ears, and eyes. Dogs with white coats and unpigmented skin are also at risk. Excessive sun exposure can cause a dog to develop skin cancer. Certain types of skin tumors, such as hemangiomas, hemangiosarcomas, and squamous cell carcinomas are associated with ultraviolet light exposure.

On hot days, dogs may also overheat if allowed to sunbathe for too long, although most dogs will instinctively move out of the sun when they become too hot.

Brachycephalic (flat-faced dog breeds) are particularly at risk for heat stroke. These breeds suffer from a condition called brachycephalic airway syndrome. Affected dogs have difficulties breathing and are not able to cool themselves down efficiently. Brachycephalic dogs should never be left outside on a warm day, even with access to shady areas. Overweight dogs, dogs with thick coats, and large breeds are also at increased risk for heat stroke. Medical conditions such as tracheal collapse and laryngeal paralysis can also increase the risk of developing heat stroke.

Signs of heat stroke include heavy panting, difficulty breathing, vomiting, weakness, hypersalivation, collapse, and seizures. If you suspect that your dog is suffering from heat stroke, seek urgent veterinary attention as heat stroke can be life-threatening.

To keep your dog safe while spending time outdoors, ensure that there is shade available as well as plenty of fresh water. Bring your dog inside between 10:00 am and 4:00 pm on hot days when the sun is most intense.

Apply sunscreen to unpigmented areas of your dog’s skin. Use a sunscreen specially formulated for pets that has non-toxic ingredients in case your dog licks and ingests the sunscreen. Remember to reapply the sunscreen often if your dog is spending long periods in the sun.

If sunscreen isn’t practical, or if your dog needs additional sun protection, physical barriers such as UV vests provide protection from the sun.


Featured Image Credit: dendoktoor, Pixabay

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