Tired vs. Exhausted: Know the Difference

July 7, 2026

By Dr. Jacob Klos, DVM

Every summer, I see dogs in my practice who were pushed too hard. Not intentionally. Their owners love them. But the signs of overexertion in dogs are subtle, and in summer heat, the margin between healthy fatigue and dangerous exhaustion shrinks dramatically.

Here's how to tell the difference.

What "good tired" looks like

After appropriate exercise, a healthy dog will pant moderately, drink water, and settle down to rest within 15 to 30 minutes. Their breathing returns to normal relatively quickly. They're calm but still responsive. They eat normally at their next meal. They recover fully within a few hours.

This is healthy fatigue. It means the body was challenged appropriately and can recover without difficulty.

What exhaustion looks like

An overexerted dog may show some or all of these signs:

Excessive panting that doesn't slow down: If your dog is still panting heavily 30 minutes after stopping activity, they've been pushed too far.
Stumbling, wobbling, or loss of coordination: These indicate the muscles and nervous system are depleted. This is a warning sign.
Vomiting or diarrhea during or after exercise: The body is in distress and redirecting resources.
Glazed or unfocused eyes: The dog is no longer mentally present. This can indicate heat exhaustion or overexertion.
Refusing water or unable to drink: A dog that won't drink after exercise may be nauseated from overexertion.
Dark red or purple gums: Normal gums are pink. Dark or discolored gums indicate poor oxygenation or circulation and require immediate veterinary attention.
Collapse: If your dog lies down and cannot or will not get up, this is a medical emergency.

Why summer makes it worse

Dogs cool themselves primarily through panting, which is far less efficient than human sweating. On hot days, the body has to work harder to cool itself AND fuel the muscles during activity. These competing demands can overwhelm the system quickly.

Humidity compounds the problem. When the air is saturated with moisture, panting becomes even less effective because evaporation slows.

The combination of high temperature and high humidity is the most dangerous exercise environment for dogs. Even dogs that handle long hikes in spring can overheat in 20 minutes on a humid July afternoon.

The dogs at highest risk

Brachycephalic breeds: Bulldogs, Pugs, French Bulldogs, and other flat-faced breeds have compromised airways that make cooling through panting even less efficient.
Overweight dogs: Extra body mass generates more heat and places more strain on the cardiovascular system during activity.
Senior dogs: Older dogs have reduced thermoregulatory capacity and may not be able to keep pace with their younger energy levels.
Dark-coated dogs: Dark fur absorbs more solar radiation than light fur.
Dogs not conditioned for the activity: Weekend warrior syndrome applies to dogs too. A dog that walks 20 minutes a day shouldn't hike 3 hours on Saturday.

The rules I follow

Exercise in the coolest parts of the day: Early morning or evening. Avoid 10 a.m. to 4 p.m. in summer.
Carry water and take frequent breaks: Every 15 to 20 minutes during activity, stop for water and shade.
Watch, don't assume: Your dog will not tell you when they've had enough. Many high-drive breeds will keep going until they collapse. You have to be the one who decides when to stop.
Match the activity to the dog: Not every dog is built for every activity. Know your dog's limits and respect them, especially in heat.
Give recovery days: After intense activity, the body needs time to repair. Alternate high-intensity days with rest or low-intensity days.

When to call the vet

If your dog shows any signs of heat exhaustion (panting that won't stop, wobbling, vomiting, dark gums, collapse), move them to a cool area, apply cool (not cold) water to their body, and get to a veterinarian immediately. Heat exhaustion can progress to heatstroke rapidly, and heatstroke can be fatal.

To your dog's health,
Dr. Jacob Klos

Sources:

AKC: Heatstroke in dogs, signs of overexertion, exercise guidelines
AVMA: Hot weather pet safety, exercise and heat
Veterinary emergency medicine literature on exertional heat illness in canines
Veterinary sports medicine literature on exercise tolerance in brachycephalic breeds