Heatstroke is a life-threatening emergency, which occurs most frequently in the hot summer months. A dog steps over from being 'hot' to having heat stroke once their core temperature rises about 41 C (106F). Above this temperature, a dangerous chain reaction is triggered which can see destruction of blood proteins and enzymes, microclot formation, brain swelling, organ failure, and death. 

Every owner should be aware of their dog's risk factors with regards to heat stroke. For example even active fit dogs should not be exercised in the full midday heat. Also avoid leaving dogs in hot cars, and know that flat-faced breeds are at much greater risk than others. 

The dog owner should immediately begin cooling the dog. This means carrying them (where physically possible) to a cool place and out of the full sun. Pouring tepid water over the dog and immersing paws in tepid water is ideal. 

Avoid ice baths or keeping a wet towel over the dog, as this can cause peripheral blood vessels to contract, which slows cooling rather than speeds it up. 

If the dog is still showing signs of distress then immediate transfer to a vet is desirable. The vet may draw blood, in order to test for electrolyte imbalances as a result of the hyperthermia, which need correcting. 

Cool water enemas and cool intravenous fluids also aid the cooling process. If blood proteins have been damaged by the heat, then replacement plasma or colloidal fluids may be required intravenously. 

When organ damage is suspected, protective action is taken, such as giving drugs to stabilize an irregular heartbeat, medications to reduce brain swelling,  antacids to line the gut wall and antibiotics to prevent bacteria travelling from the gut into the bloodstream. 

When the patient's temperature falls to 39.5 C (103F) cooling is stopped, since the core temperature will continue to go down after active cooling has ceased. 

The success of treatment depends on how high the core temperature rose, how long the dog was hyperthermic, and how quickly they get to the vet. 

An average survival rate is just 50%, with mortality more likely in obese patients and those that took over 90 minutes to start veterinary treatment. 

Mild cases of heatstroke often respond well and go on to recover and lead a normal life. 

There is some concern amongst specialists that prolonged time at 41C can cause permanent damage to the temperature regulating areas of the brain. Thus, although the patient may recover, they may be more likely to suffer from heatstroke in the future. 

Severe cases may not recovery and die from their hyperthermia. Alternatively, the body temperature may successfully be reduced to normal, but not before organ damage has occurred. This can result in: 

The veterinarian will monitor the patient for complications and attempt to control them as they arise. 

An emergency consultation out of hours may be $200 upwards. The cost of setting up an intravenous drip is from $60, and monitoring blood tests around $100. Sick patients may need hospitalization, the cost of which varies depending on the level of care from $60 to 600 per day.

It is essential an overheated dog is cooled down appropriately and with urgency. Bear in mind the higher the dog's temperature rises, the more significant the internal damage becomes. Hence removing a hot dog immediately to the shade and offering a drink of water can be life saving. 

Unfortunately there is a full spectrum of possible outcomes, from full recovery to death, and with all shades of organ failure in between. Since heat stroke is largely a predictable and preventable condition, it truly is best avoided with a little forethought and planning. 

There are four main methods of cooling the body. These are:

In practical terms, this means common sense actions such as never leaving a dog in a hot enclosed environment (such as a car), which both radiates and conducts heat to the dog, and the dog's ability to pant is inadequate to cope. 

Never exercise a dog in the heat of the day, and always take plenty of fresh water along. Stop frequently and offer the dog water to drink, plus wet their coat if they are panting heavily. 

Never leave a dog in full sun, and always provide them with shade. Where possible, keep dogs indoors in hot weather, in an air conditioned space. If this is not possible let the dog lie on a cool tiled floor and provide a fan blowing at ground level. Also consider providing ice packs to lean against to help keep the dog cool. Be extra careful with flat-faced breeds.