Dogs do technically sweat, but only through a tiny fraction of their body: their paw pads. Unlike humans, who have sweat glands spread across nearly every inch of skin, dogs are covered in fur that would make full-body sweating useless for cooling. Instead, they rely on panting as their primary way to shed heat, a system that works well most of the time but has real limits every dog owner should understand.
Dogs Have Two Types of Sweat Glands
Your dog’s body contains two kinds of sweat glands, but only one of them helps with temperature. Merocrine glands, located in the paw pads, work much like human sweat glands. When your dog gets hot, these glands release moisture that evaporates and pulls heat away from the body. You might notice damp paw prints on a hard floor on a hot day. That’s your dog sweating.
The second type, apocrine glands, exists across the rest of the body near hair follicles. Despite being classified as sweat glands, they don’t cool your dog at all. Their job is to release pheromones, the chemical signals dogs use to communicate with other animals. So while a dog is technically covered in “sweat glands,” almost none of them are doing what you’d expect a sweat gland to do.
The reason is straightforward: evaporation only works on exposed skin. A dog’s body is insulated by fur, which actually serves a dual purpose. It blocks solar heat from reaching the skin and slows heat loss from the body. Sweating underneath all that fur would just trap moisture against the skin without evaporating efficiently. Concentrating sweat glands on the hairless paw pads is the only place the mechanism can actually work, but four small paw pads aren’t enough surface area to cool an entire body. Dogs needed a different solution.
Panting Is the Real Cooling System
Panting is how dogs handle the vast majority of their heat regulation. It works through evaporative cooling, the same principle behind sweating, but it moves the process to the moist surfaces of the tongue, mouth, and nasal passages. As air flows over these wet tissues, water evaporates and carries heat out of the body with each breath.
The mechanics are more sophisticated than they look. Research published in the Journal of Applied Physiology identified three distinct panting patterns dogs cycle through as their cooling demands increase. At rest in mild temperatures (below about 79°F), dogs simply breathe in and out through the nose. As things get hotter or during exercise, they shift to inhaling through the nose but exhaling through both the nose and mouth. When the heat demand is highest, they inhale and exhale through both the nose and mouth simultaneously. Dogs don’t stick with one pattern. They constantly oscillate between the more intense patterns, spending more time in the highest-output mode as temperature or exertion increases.
This system costs a lot of water. A dog exposed to radiant heat loses about 40 to 70 grams of water per hour through evaporation while panting at rest. During exercise in the heat, that rate jumps to 85 to 150 grams per hour. Dogs instinctively compensate by drinking more, roughly matching their water loss, which is why access to fresh water is so critical on hot days.
Why Humidity Makes Everything Harder
Panting depends entirely on evaporation, and evaporation slows down when the air is already saturated with moisture. On a humid day, the water on your dog’s tongue and nasal passages simply can’t evaporate as quickly. The panting continues, but less heat leaves the body with each breath. This is the same reason you feel hotter on a muggy day even when the temperature hasn’t changed.
This means a 85°F day with high humidity can be more dangerous for your dog than a 95°F day with dry air. If you live somewhere with humid summers, this is worth factoring into decisions about walks, outdoor time, and car trips.
Short-Nosed Breeds Face Extra Risk
Breeds like bulldogs, pugs, and Boston terriers have compressed airways that make panting inherently less efficient. Their shortened nasal passages and narrower airways reduce the surface area available for evaporative cooling and make it harder to move enough air. These breeds overheat faster and at lower temperatures than dogs with longer muzzles.
The same risk applies to dogs who are overweight, elderly, or have respiratory conditions. Any factor that reduces a dog’s ability to pant effectively, whether anatomical or medical, shrinks the margin between comfortable and dangerous.
How Overheating Progresses
A dog’s normal body temperature sits between 100.5 and 102.5°F, already warmer than a human’s baseline. Heatstroke begins when the body temperature hits 105°F or higher and the dog can no longer bring it back down. That’s a gap of only about 2.5 to 4.5 degrees between normal and emergency, which can close quickly during exercise, in a parked car, or on a hot sidewalk.
Early signs include heavy, rapid panting, excessive drooling, and restlessness. As the condition worsens, you may see bright red gums, stumbling, vomiting, or collapse. Heatstroke is a medical emergency that can cause organ damage and death. Because dogs can’t shed heat the way humans can, they cross the line from “hot” to “in danger” faster than most people expect.
Practical Ways to Help Your Dog Stay Cool
Since your dog’s cooling system has built-in limitations, a few simple habits make a real difference. Keep fresh water available at all times, especially outdoors. On hot days, walk during early morning or evening hours when pavement is cooler and air temperatures are lower. Watch for damp paw prints and heavy panting as signals your dog is actively working to cool down.
Shade matters more for dogs than for people. A dog lying in direct sun absorbs heat through the coat while simultaneously trying to pant it away, fighting against itself. Moving to shade or an air-conditioned space immediately tips the balance back in your dog’s favor. Cooling mats, wet towels on the belly and paw pads, and kiddie pools all help by giving the body additional surfaces for heat to escape, supplementing what panting alone can handle.