Heatstroke in dogs: signs, first aid and prevention

What heatstroke is

Dogs cool themselves mostly by panting. When the heat they gain from the environment or exercise outruns that cooling, body temperature climbs and organs start to fail. The Merck Veterinary Manual for pet owners calls heatstroke an emergency and gives a normal rectal temperature for dogs and cats of about 101.5–102°F (38.6–38.9°C).

Signs to watch for

Merck lists:

• hot skin;
• rapid, heavy panting;
• drooling;
• vomiting;
• distress;
• uncoordinated movement;
• collapse or unconsciousness.

Bright red or, later, pale or bluish gums, diarrhea (sometimes bloody) and seizures can also occur as heatstroke progresses.

First aid, step by step

1. Move out of the heat. Shade, air conditioning, a cool floor. Stop all activity.
2. Cool the body. Use cool water, ice packs or wet towels on the head and body, especially the belly, as Merck describes. Replace towels as they warm up; a towel left on a hot dog can trap heat.
3. Add airflow. A fan, or the car’s air conditioning on high.
4. Head to the vet. Call ahead and keep cooling on the way.
5. Offer small sips of water once the temperature starts to fall and the dog is alert. Do not force water into the mouth of a weak or unconscious dog.

If you have a thermometer, the clinic will want to know the readings. Stopping active cooling once the temperature gets close to normal helps avoid overshooting into hypothermia — your veterinarian can guide you by phone.

What not to do

Don’t	Why
Immerse the dog in ice-cold water	Merck advises against it; it can slow heat loss and overcool
Cover the dog with a wet towel and leave it	The towel warms up and traps heat
Force water into the mouth	Risk of aspiration in a weak dog
Skip the vet because the dog looks better	Organ damage can show up later

Which dogs are most at risk

• Flat-faced (brachycephalic) breeds such as Bulldogs, Pugs and Boston Terriers. Merck notes that short-nosed breeds can overheat from stress or excitement even on cool days.
• Overweight dogs and dogs with heart or breathing problems.
• Puppies and senior dogs.
• Thick-coated breeds in hot climates.
• Working and very active dogs that keep going despite the heat.

The parked-car danger

The inside of a parked car heats up quickly, even with windows cracked and on days that do not feel very hot. A few minutes can be enough. Never leave a dog in a parked car in warm weather.

Prevention

• Walk at cooler times, early morning or evening, and shorten walks on hot days.
• Test the pavement with the back of your hand; if it is too hot for you, it is too hot for paws.
• Provide shade and fresh water at all times outdoors.
• Skip intense exercise in heat and humidity, especially for at-risk breeds.
• Watch for early signs: a dog that lags behind, seeks shade or pants hard needs a break and cooling.
• Keep weight healthy, which reduces heat stress.

Cats and heat

Cats are less often affected because they rarely exercise in the heat, but they can overheat when trapped in hot rooms, sheds, cars or carriers. Panting in a cat is never normal and needs prompt veterinary attention.

After heatstroke

Dogs that survive heatstroke are often hospitalized for monitoring and fluids, because complications can appear over the following days. Follow your vet’s instructions carefully and ask how to protect your dog from heat in the future: once a dog has had heatstroke, it may be more vulnerable.

Related: pet first aid guide and wounds and bleeding in dogs.