Cats never show heat until they are in trouble. A dog pants at the first hot afternoon; a cat hides and goes quiet, and by the time it is open-mouth breathing on the bathroom tiles its temperature may already be above 40 °C.

Cats hide heatstroke until it is late

Normal rectal temperature in a cat is 37.5 to 39.2 °C. Cats cool themselves by sweating through the paw pads and by grooming, not by panting, so panting at rest is abnormal and always worth acting on. Heatstroke begins around 40 °C and organ damage starts somewhere above 41 °C. Signs in order of appearance: open-mouth breathing, thick drooling, bright red gums and tongue, restlessness turning into weakness, vomiting, wobbling, then collapse and seizures. Pinpoint bruises on the gums and ears mean clotting has already failed.

Risk is not evenly spread. Flat-faced breeds (Persian, Himalayan, Exotic, British Shorthair) cannot move air efficiently; obese cats, cats over ten and cats with heart or kidney disease overheat first. So does a long-haired black cat asleep in a west-facing window.

Cooling a cat, and the four things not to do

Move the cat to the coolest room, wet the belly, armpits and paws with cool — not iced — water, and put a fan on it. Check the temperature every five minutes and stop cooling at about 39.5 °C; going lower risks rebound hypothermia.

  • No ice baths and no ice packs on the skin: they constrict surface vessels and slow the loss of heat.
  • No rubbing alcohol on the paws. Cats absorb and lick it, and it is toxic.
  • No forced drinking or syringing water into a cat that is dull; it aspirates.
  • No waiting to see if it improves. Heatstroke damages kidneys, gut and clotting within hours, and a cat that looks better after cooling still needs bloodwork.

The car: ten minutes is enough

On a 26 °C day a parked car passes 40 °C in ten minutes and 48 °C in half an hour. Two centimetres of open window change almost nothing. A cat left in a car for five minutes in July is a cat in an oven, and the same goes for an idling car with the air conditioning off or a van whose AC fails in stationary traffic.

If you find a cat in a hot car, note the plate, call the police and stay with the car. Breaking a window is defensible in some countries and not in others; in China call 110 and let them decide.

Pavement, sunburn and the flat-faced cat

Asphalt reaches 60 °C when the air is 31 °C, enough to burn paw pads in under a minute. Test with the back of your hand for five seconds. White ears and noses burn, and repeated sunburn on ear tips leads to squamous cell carcinoma, so keep pale cats out of midday sun. Never use human sunscreen: zinc oxide is toxic when licked off.

Moving a cat by car, plane or train

In any vehicle the cat travels in a carrier, belted in or wedged behind a seat, covered with a thin towel. A loose cat is a projectile in a 50 km/h stop, and one under the pedals causes the crash. Stop every two hours for water; open the carrier only inside a closed car.

Fly only in an IATA-approved crate, with a health certificate and a rabies vaccination at least 21 days old. Many airlines refuse flat-faced breeds in cargo, and rightly so. Entering China requires an import permit, an official veterinary certificate issued within a short window before departure and a rabies antibody titre test, and quarantine rules vary by port and by whether the animal qualifies for home quarantine — check with the customs office at the arrival airport, not with a forum. On Chinese railways, pets other than guide dogs are not allowed in passenger carriages; a few routes run a pet consignment service, which is not carry-on.

For a cat that screams for six hours, ask the vet about gabapentin an hour before departure and use a feline pheromone spray. Never sedate with an old antihistamine from the cupboard.

Heat at home in 三伏天, and the power cut

A cat needs 40 to 60 ml of water per kilogram a day, more in heat, most of it from wet food. Put bowls in every room, add a fountain if it prefers running water, and keep one in the coolest room. Do not shave to the skin: the coat insulates and blocks sunburn. Brush out the undercoat instead.

During 三伏天 the real emergency is a power cut at 38 °C. Know which room stays coolest, keep two frozen bottles in the freezer and a battery fan, and close the curtains on the sunny side at noon. Above 32 °C indoors with panting, it is a veterinary problem, not a comfort problem.

Go now, not in the morning

Call the clinic and say the words "heatstroke, temperature above 40": that gets a cat seen immediately. On the way, keep the air conditioning on the cat, not on you, and wet the carrier towel. The emergency guide covers the first ten minutes in more detail, and the health section covers the kidney and heart conditions that make a cat heat-sensitive in the first place.

Frequently asked

My cat is panting after lying in the sun. Is that heatstroke?

Panting at rest is always abnormal in a cat, but a cat that stops panting once moved to a cool room, drinks, and behaves normally is probably just hot. Take the rectal temperature. Above 40 C is heatstroke and needs a vet now, even if the cat seems to recover after cooling.

How hot is too hot to leave a cat in a car, even briefly?

There is no safe outside temperature. At 26 C the cabin passes 40 C in about ten minutes, and cracking the windows barely changes it. If you cannot take the cat with you, leave it at home; a five-minute errand in July is enough to kill.

Should I shave my cat for summer?

No, not to the skin. The coat insulates against heat and protects pale skin from sunburn; shaving can make overheating worse and exposes the ears and nose. Brush out the undercoat daily instead, and give the cat a cool tiled floor and shade.