Dog Heatstroke: What to Do and the Signs That Mean Go Now

If your dog is staggering, vomiting, seizing, has gray or bright-red gums, or has collapsed, stop reading this page. Start cooling now: pour cool water over the head, neck, chest, and belly, add a fan or the car’s AC, and get to the nearest emergency vet while you do it. Everything below explains why, but that sentence is the page.

Heatstroke is a fast-moving, life-threatening emergency, not a wait-and-see condition. This page covers only what named veterinary sources (the AVMA, Cornell’s Riney Canine Health Center, the American Red Cross, the ASPCA, VCA Animal Hospitals, and UK veterinary research behind the “cool first, transport second” guidance) publish on recognizing and responding to it. There’s no dosing, no diagnosis, and no treatment protocol here beyond first-response cooling on the way to professional care. The vet wins, every time, at every step.

Early Signs: Your Window to Act Before It’s an Emergency

Catching heat stress early is the best outcome, because it means you can cool your dog down before it becomes heatstroke. The AVMA and Cornell both list these as early heat-stress warning signs:

• Heavy or excessive panting
• Restlessness or seeking shade
• Whining
• Reluctance to move or play
• Excessive drooling
• Increased thirst
• Lethargy

If you see any of these on a hot day, act immediately: move your dog into shade or air conditioning, offer water, and stop activity. Don’t wait to see if it passes on its own. If signs don’t improve within a few minutes, or if anything below appears, go to a vet now.

Emergency Signs: Stop Reading, Get to the Vet

These signs mean heatstroke is likely already underway, per Cornell, the AVMA, and the ASPCA:

• Difficulty breathing or a sharply elevated breathing rate
• Dry, sticky, or abnormally colored gums (pale, bright red, or blue-gray) or bruising in the gums
• Weakness or stumbling
• Disorientation or confusion
• Vomiting or bloody diarrhea
• Tremors or seizures
• Collapse

Any one of these is a “go now” emergency. Begin cooling (next section) and get to the nearest emergency or 24-hour veterinary hospital immediately. Don’t wait to see if the dog “comes around” first.

What Temperature Counts as Heatstroke, and What That Number Does and Doesn’t Tell You

Sources publish slightly different figures, and it’s worth showing the range rather than picking one number to sound authoritative:

Reading	Temperature	Source
Normal range	~100.5–102.5°F (Cornell) / 99.5–102.5°F (Red Cross)	Cornell Riney Canine Health Center; American Red Cross
Act now	Above 104°F	American Red Cross
Heatstroke	105°F and above	Cornell Riney Canine Health Center
Critical / organ-failure range	Roughly 107–109°F	VCA Animal Hospitals
Active-cooling stop point	~103°F, reached within about 10–15 minutes of cooling	American Red Cross

None of these numbers are a DIY diagnostic tool. They tell you how urgent the situation is, not whether you can handle it at home instead of at a clinic. If you have a thermometer and a safe way to take a rectal temperature, that reading helps you know when to stop active cooling (around 103°F, per the Red Cross); it does not replace getting the dog to a vet. If you don’t have a thermometer, don’t delay cooling or transport to go find one. Every temperature figure on this page ends the same way: this does not replace emergency veterinary care.

Cooling: What Works, and What to Stop Doing

Current veterinary guidance from the Royal Veterinary College, corroborated by the British Veterinary Nursing Association’s coverage of the same research, uses a simple phrase: cool first, transport second. Start cooling immediately, before or during the drive to the vet. Don’t wait until you arrive to begin.

Do this

• Move the dog out of heat immediately: shade, indoors, or an air-conditioned car.
• Pour or spray cool (not ice-cold) water over the head, neck, chest, abdomen, armpits, groin, and feet, per VCA Animal Hospitals and Cornell. For double-coated breeds, make sure water reaches the skin, not just the coat surface.
• Add airflow: a fan, or the car’s AC on the drive to the vet, since evaporation is what actually pulls heat away.
• Keep cooling going during transport. This is the “transport second” half of the guidance: cooling doesn’t stop because you’re now driving.
• Stop active cooling around 103°F, per the Red Cross. Temperature keeps dropping for a while after you stop, and continuing past that point risks overcooling into hypothermia.

The RVC’s own research shows why speed matters this much: dogs with mild heat-related illness survived at roughly 97%, compared to roughly 43% for dogs whose heatstroke reached the severe stage. That’s a reason not to delay the first cooling step, even for a few minutes, while you find car keys or a leash.

Newer UK veterinary research has also examined cold-water immersion (rather than pouring) as an effective option for young, otherwise healthy dogs, while evaporative cooling (pouring water plus airflow) remains the safer default across ages and health conditions, including for older dogs or dogs with underlying conditions. If you’re unsure which applies to your dog, pouring water with a fan or AC running is the option every source agrees on.

Don’t do this

• Don’t use ice or ice-cold water. The Red Cross explicitly warns against ice-water immersion; VCA notes ice packs are “no longer recommended.” Very cold water can cause blood vessels near the skin to constrict, which traps heat instead of releasing it, and can trigger shivering, which generates more heat.
• Don’t drape a wet towel over the dog and walk away. VCA is direct: don’t cover the dog with wet cloths. A towel that isn’t continuously re-wetted dries out and traps heat instead of releasing it, the opposite of what you’re trying to do. If you’re using a towel, keep it soaked and moving, or switch to pouring water directly.
• Don’t use rubbing or isopropyl alcohol on paw pads. VCA notes this older method is no longer recommended.
• Don’t assume cooling means it’s over. A dog that cools down and seems normal still needs a vet visit; see the next section.

Even After Cooling Works, You Still Need a Vet

This is the step people skip, and it’s the one that matters most. The American Red Cross and Cornell both note that heatstroke can trigger complications (kidney failure, abnormal heart rhythm, neurological problems, respiratory arrest, or clotting disorders) that show up hours to days after the dog appears to have recovered. A dog that seems fine after cooling can still be in danger internally.

Treat successful field cooling as first aid, not treatment. Call ahead if you can, and get to a vet the same day heatstroke was suspected, even if your dog is walking around, drinking water, and acting normal by the time you’re in the car.

Brachycephalic Dogs (and Cats) Are at Higher Risk, Even in Moderate Heat

Flat-faced breeds can’t pant as effectively as longer-nosed dogs, which is their primary mechanism for shedding heat. The AVMA flags short-nosed breeds generally as higher-risk; Cornell and VCA both name the same core breed group specifically: pugs, bulldogs, Boston terriers, and boxers.

Other factors that raise heatstroke risk, per Cornell, the ASPCA, and VCA:

• Being overweight
• Senior or elderly age
• Heart or respiratory disease
• A thick or dark coat
• Wearing a muzzle, which restricts panting

If your dog checks any of these boxes, the early-sign window above matters even more. Don’t wait for the emergency signs to act. Flat-faced dogs in particular can show serious signs at only moderately elevated temperatures where a longer-nosed dog would still just be panting hard. When in doubt with a higher-risk dog, call your vet before a hot activity, not after signs appear.

Cats Get Heatstroke Too, and Persians Carry the Same Flat-Faced Risk

Cats are less commonly discussed in heatstroke guidance, but the ASPCA names Persian-type cats alongside pugs as a flat-faced risk group facing the same reduced-panting problem. Watch for panting, lethargy, and drooling as early signs; collapse, reddened skin, bright red gums, tremors or seizures, disorientation, and vomiting or diarrhea (sometimes bloody) as emergency signs. Labored or wheezing breathing in a cat is an emergency sign, not a symptom to monitor.

The response is the same as for dogs: move to a cool area, begin cooling with cool (not ice-cold) water and airflow, and get to a vet immediately. If your cat shows any emergency sign, don’t wait to see whether cooling alone resolves it.

The Hot-Car Risk That Causes Preventable Heatstroke

A parked car heats up far faster than most people expect, which is why leaving a pet in one “for a minute” is a common and dangerous mistake:

• The CDC cites roughly a 20°F rise within the first 10 minutes, even with a window cracked.
• Cornell cites a separate figure: at 70°F outside, a car’s interior can climb 40°F within an hour, with most of that increase happening in the first 15 to 30 minutes.

Never leave a pet unattended in a parked car. No amount of time is safe, and cracking a window doesn’t meaningfully change the outcome. If you see a pet showing distress signs inside a parked car, this is the same emergency-sign checklist above: get the animal out, begin cooling, and get to a vet.

If You Suspect Poisoning Instead of (or Alongside) Heatstroke

Heat and toxin exposure can look similar or happen together, a dog that got into antifreeze on a hot day, for example. If you suspect poisoning specifically, the ASPCA Animal Poison Control Center is reachable 24 hours a day, 365 days a year at (888) 426-4435 (a consultation fee may apply). This is a poison-specific line, not a general heatstroke hotline. For heatstroke itself, the right call is always your nearest emergency or 24-hour veterinary hospital, which doesn’t have a single national phone number to list here. If you’re not sure which you’re dealing with, treat it as both: begin cooling and get to a vet, and mention any suspected ingestion when you call ahead or arrive.

Cool First, Call the Vet

Recognize early (heavy panting, restlessness, seeking shade) and you can often stop heatstroke before it starts. Recognize late (staggering, vomiting, seizing, collapse) and the sequence is the same every time: cool first, transport second, and see a vet even after cooling works. None of this replaces a veterinarian. It’s what gets your dog or cat to one in the best possible shape.

For the rest of what changes by disaster type, including how heat risk interacts with power outages and evacuation, see the pet emergency playbooks hub. If a hurricane or wildfire evacuation is what’s putting your pet in heat risk in the first place, hurricane pet preparedness and wildfire smoke pet safety cover those specific scenarios, and pets and power outages covers the AC-loss angle. If you have multiple pets and need to decide who gets attention first in a fast-moving emergency, see which pet to evacuate first.