Summer is here, and we’ve shed our coats. Dogs and cats don’t have that luxury, but their fur, which keeps them warm in winter, also protects them in the summer by preventing them from taking on too much heat. It’s a fine system until it gets too hot, at which point it can be overwhelmed, with potentially dire consequences.

Dogs and cats are homeotherms, meaning they maintain a fairly constant body temperature of 101 to 102 degrees, according to James H. Jones, an expert in comparative animal exercise physiology and thermoregulation at University of California at Davis. “The trick to being a homeotherm is to be able to adjust internal heat gain and heat loss . . . in order to maintain a constant body temperature,” he said.

Unlike humans, dogs and cats can’t sweat to cool themselves. A common misconception is that cats and dogs sweat through their paws, but, says Kimberly May, a veterinarian with the American Veterinary Medical Association, “any secretions there or from their nose, mouth or tongue are not for sweating; they’re for protection and moisture and are insufficient to cool the blood,” Cats and dogs are able to release heat in other ways, though.

Conduction transfers excess internal heat when animals contact objects cooler than themselves, such as when lying on cool tile. Convection transfers heat away through cold air or water; this occurs when an animal jumps into a pool, is hosed down or has a fan trained on it. Evaporation dissipates heat from within the body when a dog or cat pants. This is their only internal vehicle for releasing stored body heat.

Counterintuitively, fur can help an animal cope in the heat.

“Fur actually insulates the body in cold weather and helps prevent the body from taking on too much heat in warm weather,” says Jones. “Fur acts as a thermal regulator to slow down the process of heat absorption.”

By shedding in hot weather, dogs and cats make their coats more suitable for heat protection instead of warmth. “The thick undercoat that’s needed in order to trap body heat in the cold weather is not required in warm weather. The remaining outer coat is optimal for handling heat as long as it’s not extreme,” explains veterinarian Marty Becker, author of numerous books about dogs and cats.

For this reason, experts agree, it can be a mistake to shave or dramatically trim the coat of a dog or cat in the summer. While it may seem that it would be cooler, it can actually make an animal hotter. In addition, cats and dogs need protection from sunburn and insect bites.

“Dogs have developed their hair coats for a reason. It’s a barrier between the dog’s skin and the sun,” according to Emily Rogell, medical director of the Metropolitan Emergency Animal Clinic in Rockville. “The less heat and sun reach the skin, the less hot the dog will be. I don’t recommend clipping or shaving unless there is a medical reason,” such as a skin condition or terribly matted fur.

Shaving could also contribute to dehydration, says Jones, noting that research has found that “camels in the desert that are shaved, for example, do worse than those with fur, requiring more water evaporation to stay cool.”