Why can thick fur be a problem on a hot day?

Picture a hot summer afternoon, when the sun warms your arms and the path feels toasty under your shoes. A big fluffy dog flops down in the shade of a tree. It lies very still, with its tongue hanging out.

That dog wears a thick fur coat everywhere it goes, and it can never take it off. On a cold day, the coat seems perfect. So why can thick fur be a problem on a hot day?

Inside a furry animal, the body is busy all day long. It uses food to power running, breathing and even resting, and all that work makes warmth. So a dog carries its own small heater inside, even while it naps.

Thick fur is made of thousands of hairs growing close together. Between them, the hairs catch tiny pockets of air and hold them still. That still air sits right next to the skin like a soft, invisible blanket.

This blanket of trapped air is called insulation, which means a layer that keeps warmth from slipping away fast. Insulation keeps the warmth from the body close to the skin. On a snowy day, that is exactly what a dog needs to stay cozy.

On a hot day, the air around the dog is warm too. Warm air cannot carry the body's warmth away the way cold winter air does. And the insulation in its fur still holds that warmth in, because fur cannot tell summer from snow. So where do you think all that warmth goes?

Only a little of it slips out through the thick fur. The body never stops making more, so the warmth keeps building up, minute after minute. Soon the dog is carrying far more warmth than it needs.

When a body holds more warmth than it can let go, it starts overheating, which means getting too hot on the inside. Overheating makes an animal feel tired, thirsty and wobbly. That is why thick fur becomes a problem on a hot day.

Insulation, overheating. A furry animal's body keeps making warmth, and the insulation in thick fur holds that warmth in, so on a hot day, when warm air cannot carry it away, the animal starts overheating.

Rest well tonight, and may you feel cool and cozy, the right amount of warm.