Dogs (and cats) are much more sensitive to heat that human beings, and a hot day can be very dangerous if they are over-exposed to the heat. The kind of heat that makes us exclaim “Wow, its way too hot to get in the car!” can kill an animal in minutes. We can put the windows down, turn on the air-conditioning or get out of the car when we are sweating buckets, but a dog CANNOT do any of this. And cars are not the only death trap. Animals have more problems than human beings when it comes to lowering their body temperature by themselves. Even though this article is about dogs, we can apply the same rules to cats.

Heat stroke is the common name for hyperthermia, which is a rise in body temperature so extreme that there is a risk that the physiological processes will not function correctly or be damaged. The effects can be temporary or permanent; they can cause death and the amount of time the animal needs to be exposed to the heat and the temperature is different in every case. The older the animal is, the more serious the damage will be.

In just 10 minutes, a dog or a cat can die inside a car. Sometimes, even quickly rescuing the animal is not enough to avoid vascular problems, haemorrhaging or cerebal edema. It is hard to believe that there are so many irresponsible pet owners. “I’ll just be five minutes” becomes a drama when they return, as the animal has died.

Body Temperature

Mammals (and birds) have a mechanism that allows their body to regulate the temperature of deep-seated organs. As a result, they can survive a wide range of outdoor temperatures. However, this thermoregulation system is not efficient enough in extreme cases, and therefore the inner body temperature carries on rising relentlessly, damaging the organs.

The average body temperature of dogs is 39ºC. When it rises above this, a growing number of internal failures take place, to the extent that the thermoregulation system also loses control of the situation, which can culminate in the death of the animal.

Controlling Body Temperature

Dogs do not sweat and can only eliminate heat by means of three mechanisms:

  • Panting
  • Sweating (only through the pads of the feet)
  • Via isolated areas without much fur (such as the belly)

Risk Factors

Below is a list of factors that can cause heat stroke, and therefore must be monitored:

  • Environment:

  • High outdoor temperatures 
  • Moderate outdoor temperatures after various days of suffocating heat
  • High atmospheric humidity, which makes it difficult for the animal to eliminate water vapour.
  • Confined and/or badly ventilated spaces: the car, a room, a small patio, a balcony, a pet carrier, a ship’s hold....
  • Water: a small amount, water that is not fresh or not regularly replaced.
  • A lack of shade or very reduced shade.
  • Cement floors.
  • Do you keep your dog tied up outside? Then there is an added risk it will choke trying to get to the shade or more water.


  • Very young or very old.
  • Sick: heart failure, respiratory failure, stress.
  • Brachycephalic (very flat nose): Bulldog, Pug, ultra-typed Persian Cat, Boxer, Pekingese, ...
  • Obesity: the skin better insulates the animal.
  • Fur colour: dark colours absorb more heat.
  • Digestion: DO NOT give the animal food during the day, but at sunset.
  • Exercise is completely out of the question during the hottest time of the day.
  • When the animal is nervous

Heat Stroke

Shortness of breath

Heat stroke” normally occurs after a very hot day or on a moderately hot day following several consecutive hot days. Heat depletes the sugar and salt reserves of the dog’s body, so the longer the period of heat lasts, the quicker heat stroke can occur. Under these circumstances it does not take much more (exercise, lack of water, nerves...) to provoke it. “Heat stroke” can finish your dog off in little more than 15 minutes.

    • They appear when the internal body temperature rises above 42ºC.
    • Asthenia: Lack or considerable drop in strength
    • Muscle tremors.
    • Cyanosis: Bluish skin caused by insufficient oxygen reaching the blood
    • Refusal to move.
    • Very fast or troubled breathing.
    • Increased heart rate
    • Discoloration of the mucous membranes: gums, ...
    • Alterations in salivation.
    • Staggering.
    • Loss of body salts and sugar.
    • Petechiae. Small spots on skin caused by bleeding
    • Gastrointestinal bleeding.
    • Liver failure.
    • Renal failure.
    • Cerebral edema.
    • Multiorgan failure.
    • Patients admitted in a serious condition can die within 24 hours as a result of respiratory depression and respiratory arrest.




First aid

The temperature of the patient cannot be lowered in one foul swoop because this will cause hypothermia, which has the same disastrous results. The temperature has be lowered gradually and the animal must be rehydrated and recuperate the sugar and salt lost.

  • If you can, take the animal to a veterinary clinic immediately by car, and during the journey:
    • First and foremost, dampen (without wrapping or covering the animal) the neck and the head using cloths soaked in tepid water or a water spray. NEVER cover the animal with damp towels.
    • Place an ice cube on the bridge of the nose, the groin and under the armpits.
    • Dampen the mouth without forcing the animal to drink, and without letting it drink to excess.
  • If you cannot take the animal to a veterinary clinic immediately: Take it to a cool place.
    • Immerse it in water that is at a temperature of around 20ºC or spray it with water that is at that temperature, until it breathes normally.
    • First and foremost, dampen (without wrapping or covering the animal) the neck and the head using cloths soaked in tepid water or a water spray. NEVER cover the animal with damp towels. If possible, use a fan to assist you.
    • Place an ice cube on the bridge of the nose, the groin and under the armpits.
    • Dampen the mouth without forcing the animal to drink, and without letting it drink to excess.
    • When the animal breathes normally, keep it on a damp towel.
    • Take it to the vet as soon as possible, and explain everything you have done to the vet. It is ESSENTIAL that a vet keeps the situation under control and monitors the animal to see how it progresses. In addition ,the animal will need medication to recover. Normal breathing does not rule out brain damage and other consequences of a shock like this. Therefore we would like to reiterate that you MUST TAKE THE ANIMAL TO THE VET as soon as possible.


  • In all situations:
    • Always have fresh clean water available.
    • Stay in a large, well ventilated area.
    • Make sure there is a large, shady area available.
    • Give the animal food very early in the morning or last thing at night.
    • Take it for a walk early in the morning and last thing at night, as well as for a brief walk at midday so the animal can go to the toilet.
    • Avoid exercise.
    • Keep the animal in your line of vision.
    • If you travel with the animal and the car does not have air-conditioning, you should take ice, a couple of towels, and water. When you stop, if you see that the animal is hot, wet the towel and let it lie down on it or put its feet on it (to reach its paws). From time to time you can rub the paws and the bridge of the nose with an ice cube.
  • High risk animals:
    • If you have a garden, let the animal play for a while under the sprinkler system.
    • Do not take the animal for a walk at midday if you live in an area where there is no shade or on a square that is constructed with tarmac or cement. These are called “hard squares” and are very fashionable in certain cities.
    • Ask your vet whether you should give the animal a glucose supplement or mineral salts.
    • In the case of puppies or elderly dogs that are inside on sweltering hot days, put down damp towels that they can lie on and keep replacing them, a container with frozen water that “chills” the place while it melts, and keep the blinds down and the windows open when the sun is on the room.


Regrettably, this issue is very common. It is hard to believe that people can be so stupid. Leaving a dog in the car in summer is condemning it to death within minutes.

The way in which the temperature rises in the car

A minimum amount of common sense is enough for a lot of people to realise that leaving their dog in a parked car in the sun can be dangerous once a certain amount of time has passed. What they don’t know is how little time it takes. Leaving the car in the shade or with the windows slightly down only means prolonging the agony.


On a hot day, the glass of the windows attracts light which is transformed into heat inside the vehicle, meaning that the temperature rises to a very dangerous level:

Just parked. Windows down.
30 º
30 º
+ 10 minutes
30 º
39 º
Risk of heat stroke
30 º
43 º
+ 30 minutes
30 º
49 º

The ratio at which the temperature rises on a very hot, humid day: + 0.7ºC per minute.


For this very reason, we DO NOT RECOMMEND TRANSPORTING ANIMALS IN A SHIP’S HOLD in summer. Countless dogs and cats have died on the journey and a lot of them have arrived at their destination and have to be admitted urgently to veterinary clinics, with varied predictions about their health. Holds DO NOT have a cooling system, and the unbearable heat of the atmosphere is coupled with the heat given off by the engines and the deafening noise. DO NOT keep the animal in a special carrier or leave it in your car. It is like playing Russian roulette with four bullets in the chambers. You must also remember that you are not allowed to go down and check on the animal.


Written by F. Altarriba