Dogs regulate their body temperature primarily through panting, which serves as their version of sweating. A healthy dog maintains a core temperature between 99.5°F and 102.5°F, slightly warmer than humans. Because dogs have very few sweat glands, they rely on a combination of respiratory cooling, blood flow adjustments, and their coat’s insulating properties to stay within that range.
Panting Is the Primary Cooling System
Panting is the single most important way dogs shed excess heat. As air moves rapidly across the moist surfaces of the tongue, nasal passages, and upper airways, water evaporates and carries heat away from the body. It works on the same principle as human sweating, just relocated to the respiratory tract.
What makes panting surprisingly sophisticated is that dogs adjust their airflow patterns as they get hotter. At rest in mild temperatures (below about 79°F), a dog breathes in and out through its nose. As things warm up past 86°F, or during exercise, the dog begins exhaling through both its nose and mouth, exposing more moist tissue to airflow. Under the highest heat demands, dogs inhale and exhale through both the nose and mouth simultaneously, maximizing the surface area available for evaporation. This graduated system lets dogs fine-tune their cooling output rather than running at a single speed.
Sweat Glands Play a Minor Role
Dogs do have functional sweat glands, but only in their paw pads. These merocrine glands release moisture when a dog is hot or stressed, which is why you might notice damp paw prints on your floor on a warm day. The sweat evaporates from the hairless surface of the pads and releases a small amount of heat. But given how little surface area paw pads represent compared to the whole body, this mechanism contributes very little to overall cooling. It’s a supplementary system at best.
Blood Flow Redirects Heat to the Surface
When a dog’s core temperature rises, blood vessels near the skin dilate, allowing more warm blood to flow toward the body’s surface. This pushes internal heat outward, where it can radiate into the surrounding air. The heart compensates by increasing its output to keep blood pressure stable while more blood pools near the skin. You can sometimes see this effect in dogs with thin-furred ears, where the skin feels noticeably warmer during exercise or heat exposure.
This vascular system works in reverse during cold weather, particularly in the paws. Arteries carrying warm blood from the heart run right alongside veins returning cooler blood from the feet. The two sets of vessels sit so close together that heat transfers directly from artery to vein before the blood ever reaches the paw pad. Scientists call this a countercurrent heat exchanger. It keeps paw tissue warm enough to prevent frostbite while recycling most of the heat back toward the core, so the dog doesn’t lose precious body warmth through its feet on frozen ground. Blood vessels in the paws also open and close in response to temperature changes, controlling how much blood flows to the extremities depending on conditions.
How a Dog’s Coat Works as Insulation
A dog’s coat insulates in both directions, against cold in winter and against heat in summer. This is especially true of double-coated breeds like Huskies, Golden Retrievers, and German Shepherds. The dense, fluffy undercoat traps air in small pockets close to the skin. In cold weather, those air pockets hold body heat in. In warm weather, they trap cooler air and create a buffer between the skin and the hot environment. The longer guard hairs of the outer coat add a layer of shade, block UV radiation, and repel moisture and snow.
This is why veterinarians and groomers generally advise against shaving double-coated breeds in summer. Removing the coat eliminates the insulating air layer and exposes the skin directly to solar radiation, which can actually make the dog hotter and increase the risk of sunburn. Regular brushing to remove loose undercoat does more for summer comfort than a shave.
Why Some Breeds Overheat More Easily
Since panting depends on air flowing efficiently through the airways, breeds with shortened skulls and compressed nasal passages are at a significant disadvantage. Bulldogs, Pugs, French Bulldogs, and other flat-faced breeds have narrowed airways that make panting more physically demanding and less effective at moving heat out of the body. Research from the AKC Canine Health Foundation found that these breeds adopt an exaggerated breathing strategy under heat stress, essentially working harder and spending more energy just to achieve less cooling than longer-nosed breeds. They are also less successful at maintaining a normal body temperature when conditions get hot.
This makes flat-faced breeds genuinely more vulnerable to overheating during exercise, in warm weather, or even in moderately warm indoor environments. Obesity compounds the problem, as extra tissue generates more heat and insulates the core. Short-nosed dogs need more careful monitoring on warm days, more access to shade and water, and shorter exercise sessions than breeds with longer muzzles.
When Thermoregulation Fails
Heatstroke occurs when a dog’s cooling systems are overwhelmed and core temperature climbs to 105°F or higher. At that point, proteins in cells begin to break down, organs can sustain damage, and the situation becomes a medical emergency. According to Cornell University’s College of Veterinary Medicine, heatstroke results specifically when a dog can no longer regulate its own temperature.
The early signs include heavy, rapid panting that doesn’t slow down with rest, drooling, bright red gums, unsteadiness, and lethargy. Dogs left in parked cars are the most well-known victims, but heatstroke also happens during exercise on humid days (when evaporative cooling from panting becomes less effective because the air is already saturated with moisture), in dogs without access to shade or water, and disproportionately in brachycephalic breeds. If you suspect heatstroke, moving the dog to a cool area and applying room-temperature water to the body (not ice water, which constricts surface blood vessels and traps heat inside) can help while you get to emergency care.