All dogs pant. Panting is a normal behavior in dogs that can mean a few different things. Unfortunately, panting in dogs is sometimes misinterpreted by humans. As your dog's caregiver, you should be able to tell the difference between normal panting and panting that is a sign of distress. Here are some reasons dogs pant:

Dogs Pant to Cool Off

Even if they are not overheating, dogs will pant from exercise.

It's just like they way humans breath heavily when doing aerobic exercise. However, panting is also the primary way for dogs to cool themselves off because they don't sweat like humans do. They sweat a little bit through their paw pads, but this cannot sufficiently cool them off. Instead, dogs cool themselves through their mouths.

Panting allows dogs to release heat and exchange it for cooler air. As you can imagine, this is not a very efficient process. It's even less efficient for short-faced dogs (like  Bulldogs or Pugs). That's why dogs start to pant even when they get even a little bit warm. The hotter a dog becomes, the more intense the panting becomes.

Aggressive panting could be a sign of heat stroke or exhaustion. Along with intense panting, warning signs include bright red tongue and gums, wide eyes, and elongated appearance of the tongue. Take steps to prevent overheating by keeping your dog cool and minimizing exposure to heat. Be safe in hot weather!

Dogs Pant When Anxious or Stressed

Panting may have nothing to do with body temperature.

Many dogs will pant when they experience anxiety, stress or fear. Examples include car rides, fireworks, separation anxiety, vet visits and other stressful events. Look at your dog's body language to get a better idea of the problem. Understanding the cause of fear or anxiety in your dog can help you minimize these incidents. If panting seems to be related to fear, anxiety or stress, it's best to remove your dog from the situation as soon as you can.

Dogs Pant When Excited or Happy

Panting may simply be a sign of happiness in your dog. If so, the rest of your dog's body language will reflect this happy mood. Once things calm down, the panting should calm down and eventually stop. Note that mild panting with an open mouth and bright eyes is normal in a content, relaxed (dog even when prolonged). In fact, many people consider this to be a doggie smile!

Dogs Pant When Painful or Sick

Panting may be a sign of discomfort. Dogs are pretty good at hiding pain and illness from humans. Some dogs try harder than others to hide their discomfort. However, once they reach a certain level of discomfort they often cannot help but pant. Look for other signs of illness or pain, such as vomiting, diarrhea, limping, etc. Contact your veterinarian if you suspect that your dog is sick or injured. 

If at any time you see that panting is extremely intense and cannot be explained, you should get your dog to the nearest veterinarian immediately.