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

If your dog is staggering, vomiting, seizing, has abnormally colored or very 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.

This page owns recognition, signs, and cooling response in full depth. For hot-car prevention, the never-do list, heat wave planning, and spec-checked cooling gear, see our pet heat wave safety guide, which owns that side of the split.

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 the Royal Veterinary College and British Veterinary Nursing Association 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. Between the AVMA’s heat-stress list and Cornell’s early-overheating list, these are the signs to watch for:

• Heavy or excessive panting
• Anxiousness or restlessness
• Seeking shade
• Whining
• Reluctance to play
• Excessive drooling

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, the ASPCA, the American Red Cross, VCA Animal Hospitals, and the BVNA:

• Difficulty breathing, or an increased heart and respiratory rate
• Abnormal gum or tongue color, including a very red tongue or very red mucous membranes; VCA also names dry or sticky gums and bruising in the gums
• Weakness or stumbling
• Lethargy, which VCA lists alongside disorientation and seizures as a heat stroke sign
• 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	104°F or above	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 goal (where you stop)	About 103°F	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, and feet. VCA Animal Hospitals names the head, stomach, armpits, and feet; the Red Cross names the head, neck, feet, chest, and abdomen as the sites to cool. For double-coated breeds, Cornell says to make sure the dog is wet down to the skin, not just at the coat surface.
• Add airflow: a fan, or the car’s AC on the drive to the vet. VCA’s instruction is to mist cool water over the dog and place them in the path of a fan or air conditioning.
• 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 at about 103°F, per the Red Cross, which sets 103°F as the goal rather than a normal reading. Don’t keep cooling toward normal. VCA gives the same 103°F as the point where hospital cooling is discontinued, and says that if cooling is not discontinued the patient could develop hypothermia.

The RVC’s own announcement of this research shows why speed matters: in the earlier VetCompass work it cites, 97% of dogs treated for mild heat-related illness survived, compared with 43% of dogs treated for severe heat-related illness. That’s a reason not to delay the first cooling step, even for a few minutes, while you find car keys or a leash.

The RVC and the BVNA split the recommended cooling method by dog: cold water immersion for young, healthy dogs, and evaporative cooling (pouring over them water of any temperature that is cooler than the dog, combined with air movement from a breeze, fan, or air conditioning) for older dogs or dogs with underlying health problems. Neither source says what to do when you can’t place your own dog in one of those two groups, so the next step is ours, not theirs: if you’re unsure, pour water and add airflow, because that’s the method both sources endorse for dogs outside the young-and-healthy group.

Don’t do this

• Don’t use ice. The Red Cross says not to immerse the dog in ice water. VCA says ice packs are “no longer recommended” as a way to bring temperature down. The BVNA says iced baths, iced water, and ice coats should be avoided because they could make the situation worse. Note the scope: this rules out ice, not cold water, and the RVC still recommends cold water immersion for young, healthy dogs.
• Don’t rely on wet towels. VCA says not to cover the dog with wet cloths, because covering can prevent evaporative or radiative cooling. The RVC and the BVNA go further and call the application of wet towels outdated first-aid advice that doesn’t reduce body temperature nearly as fast as immersion or evaporative cooling. The sources aren’t unanimous here: the Red Cross’s own steps do include placing cool, water-soaked towels on the dog while running fans. What all of them agree on is that a towel is not a substitute for pouring or spraying water with airflow.
• Don’t use rubbing alcohol. VCA lists rubbing alcohol alongside ice packs as no longer recommended for bringing a dog’s temperature down.
• 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 lists abnormal heart rhythms, blood clotting problems, destruction of the digestive tract lining, kidney failure, neurological problems, and respiratory arrest as possible consequences of hyperthermia, and says many of them do not show up for hours or even days. Cornell’s list is shorter and carries no timeline: prolonged high body temperature damages every organ, and heatstroke commonly leads to acute kidney injury, blood clotting issues, and shock. 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 names the core breed group specifically as pugs, bulldogs, Boston terriers, and boxers, and VCA names pugs, bulldogs, 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. For gear sized to the flat-faced breathing problem (cooling vests, mats, fans, and carrier ventilation), see cooling gear for brachycephalic dogs, none of which is a substitute for the recognition and cooling response on this page.

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 cats alongside pugs as flat-faced animals that can’t pant as effectively. The BVNA, which writes its heatstroke guidance for cats and dogs together, adds the detail that makes cats harder to catch: panting is often the first sign, and signs in cats are often more subtle than the same signs in dogs.

The BVNA’s sign list, which it applies to both species, runs: panting, restlessness or agitation and trying to move somewhere cooler, salivating or drooling, a very red tongue, dizziness or staggering and weakness, vomiting or diarrhea, appearing confused, trembling that looks like shivering, seizure, and collapsing and becoming non-responsive. The ASPCA’s overheating list adds difficulty breathing and an increased heart and respiratory rate. Collapse in particular is the point at which the BVNA says to seek veterinary advice immediately while you keep cooling.

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 says temperatures inside the car can rise almost 20°F within the first 10 minutes, even with a window cracked open.
• 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. For the full hot-car temperature data, state hot-car law tracker, never-do list, and heat wave planning and gear, see our pet heat wave safety guide.

If you’re buying cooling gear, start here: Pet heat wave safety: gear that actually helps, spec-checked cooling mats, vests, and monitors, none of which are a hot-car fix but all of which support the prevention side of this page.

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, with dog cooling gear that works during a power outage sorting the options by power source for when the AC is the thing that failed. If you have multiple pets and need to decide who gets attention first in a fast-moving emergency, see which pet to evacuate first.