Dog Heatstroke: Emergency Signs & Cooling Protocol

By Sarah Bennett, Certified Animal Nutritionist

Heatstroke — also called hyperthermia — occurs when a dog's core body temperature exceeds 41°C (106°F). Unlike humans, dogs cannot sweat through their skin. They rely almost entirely on panting to regulate body heat, and panting becomes rapidly ineffective in hot, humid conditions or when the dog is brachycephalic (flat-faced). Once heatstroke sets in, organ failure can begin within minutes. Speed of response is everything.

Early Warning Signs (Act Now — Before It Becomes Critical)

Catch these signs early and you have the best chance of a full recovery:

• Heavy, rapid panting that does not slow down even when the dog rests
• Excessive drooling — thick, ropy saliva
• Bright red gums and tongue
• Restlessness, searching for shade or cool surfaces
• Elevated heart rate
• Body feels hot to the touch, especially the ears

Critical Signs (This Is Now a Life-Threatening Emergency)

• Gums turning pale, blue, or grey — this indicates circulatory collapse
• Vomiting and/or diarrhoea, sometimes bloody
• Stumbling, staggering, or loss of coordination
• Glazed, unseeing eyes
• Muscle tremors or seizures
• Collapse and loss of consciousness

The Emergency Cooling Protocol: Step by Step

Step 1 — Move the dog to a cool environment immediately (0–30 seconds). Get your dog out of the sun and into shade or an air-conditioned space. Every second in the heat makes the situation worse. If outdoors, aim for the deepest shade available.

Step 2 — Call your vet immediately (30 seconds). Phone your vet or emergency animal hospital while you begin cooling. Heatstroke requires professional treatment — cooling at home buys time, it does not replace veterinary care. Tell them your dog's current temperature if you have a thermometer.

Step 3 — Apply cool (NOT cold) water (1–3 minutes). Wet your dog with cool tap water — around 15–20°C (59–68°F). Focus on the neck, armpits, groin, and paw pads where blood vessels are close to the surface. Use a sponge, cloth, or pour water from a bottle. Do NOT use ice water, ice packs, or frozen towels. Cold water causes the surface blood vessels to constrict, trapping heat inside the body and making the situation worse — a paradox that has cost many dogs their lives.

Step 4 — Fan the wet dog (ongoing from minute 1). Airflow over wet skin accelerates cooling through evaporation. Use a hand fan, electric fan, or drive with car windows open and air conditioning on maximum. Fanning dry skin does very little — the water is essential.

Step 5 — Check the temperature every 2 minutes. If you have a rectal thermometer, monitor your dog's temperature continuously. Stop active cooling once the temperature drops to 39.5°C (103°F) — allowing it to fall further risks hypothermia, which is equally dangerous. Do not leave your dog unattended.

Step 6 — Offer small sips of water (if conscious). If your dog is conscious and able to swallow, offer small amounts of cool (not cold) water. Do NOT force them to drink and do not give water to an unconscious dog.

Step 7 — Transport to the vet immediately (within 5–10 minutes). Even if your dog appears to be recovering, they need veterinary assessment urgently. Heatstroke causes internal damage — to the kidneys, liver, and brain — that is not visible from the outside. Continue cooling in transit.

What the Vet Will Do

At the clinic, your dog will receive intravenous fluids to treat dehydration and support circulation, oxygen therapy if breathing is compromised, and blood tests to assess organ function. Dogs that survive the initial crisis are monitored for 24–48 hours for delayed complications including disseminated intravascular coagulation (DIC), acute kidney injury, and neurological damage. Research published in the Journal of Veterinary Emergency and Critical Care (PubMed PMID 27152886) found that dogs whose cooling began before arrival at a clinic had significantly better survival outcomes than those first cooled at the hospital.

Which Dogs Are Most at Risk?

The PDSA identifies the following as highest-risk groups:

• Brachycephalic breeds: French Bulldogs, Pugs, Bulldogs, Shih Tzus, Boxers — their anatomy makes panting far less effective
• Obese dogs — fat insulates and traps heat
• Senior dogs over 7 years and puppies under 12 months
• Dogs with heart or lung disease
• Dark-coated dogs who absorb more solar radiation
• Dogs that have previously had heatstroke — past episodes increase susceptibility

An investigation by The Guardian during the UK heatwave found that veterinary emergency visits for heatstroke increased by over 300% on days the temperature exceeded 30°C, with the majority of cases involving brachycephalic breeds and dogs exercised midday.

Prevention: The Rules That Save Lives

• Never leave a dog in a parked car, even with windows cracked, even for two minutes
• Walk dogs before 8am and after 7pm in summer — test the pavement: if it's too hot for your hand for 5 seconds, it's too hot for paws
• Always carry water on walks; offer it every 15 minutes in hot weather
• Provide shade and a paddling pool in the garden
• Never muzzle a dog in hot weather — it prevents panting
• The AKC recommends keeping exercise to under 10 minutes for brachycephalic breeds when temperatures exceed 25°C (77°F)