What do dogs often do to cool down?

Dogs often pant to cool down.

Panting is rapid, shallow breathing that helps a dog regulate body temperature. As a dog pants, air moves over moist surfaces in the mouth, tongue, and upper airways. Evaporation from these surfaces removes heat, much like sweating does in humans. Panting also increases airflow through the respiratory system, helping the dog release excess warmth.

Dogs rely heavily on panting because they have relatively few functional sweat glands. Their paw pads contain some sweat glands, but these provide limited cooling compared with the widespread sweating humans use. A dog may begin panting after exercise, in hot weather, or during excitement and stress. Thick-coated, short-nosed, overweight, and very young or old dogs can face greater difficulty in hot conditions.

Panting is normal, but heavy or sudden panting can sometimes signal overheating, pain, fear, heart or lung disease, or another medical problem. A dog that is weak, confused, vomiting, collapsing, or has very red or pale gums may need urgent veterinary attention. Panting is therefore a useful cooling behavior, not proof that a dog is simply tired. Unlike shivering, which generates heat, panting helps remove it.