Heat Stroke

Heat stroke is an emergency condition that develops with rapid elevation of body temperature to above 41⁰C (normal temperature of dog being 38 - 39⁰C) and occurs when the heat load on the dog's body greatly exceeds the capacity of the dog's panting to get rid of the heat.

The most common causes of heat stroke are confinement in overheated enclosures and exposure to hot, humid environment. This can occur when dogs are left in locked cars on hot days for periods of time, or in the back yard with little or no water and no shade on days of extreme temperatures. The chances of heat stroke are also dependent on the following:

(i)     Amount of heat the dog is exposed.
(ii)    Length of exposure to the heat.
(iii)   Amount of air circulation.
(iv)   Humidity.
(v)    Anxiety of the dog.
(vi)   Pre-existing medical problems, especially upper airway and heart related illnesses.
(vii)  Breed.

The harmful effects of heat stroke develop due to the destruction and death of the body cells. Body temperatures of 42 - 43⁰C are only tolerated for a few minutes before cell destruction occurs. The signs seen with heat stroke depend on the organs affected and the severity is proportional to the amount and duration of exposure to the heat. Below is a list of the signs seen in increasing severity of heat stroke.

(i)     Panting, brick red gums.
(ii)    Excitement.
(iii)   Rapid heart rate.
(iv)   Elevation in body temperature.
(v)    Severe respiratory distress.
(vi)    Poor peripheral circulation.
(vii)   Out of control behaviour.
(viii)  Bloody vomiting and diarrhoea.
(ix)    Generalised overall pinpoint areas of bleeding on the gums.
(x)     Absence of urination.
(xi)    Seizures and coma.
(xii)   Respiratory arrest.

Dogs can become very distressed very quickly. It is an emergency situation and veterinary treatment needs to be sought immediately if affected dogs are to have a chance of survival.

The objectives of treatment are:

(i)   To immediately reverse the elevation in body temperature.
(ii)  To correct the stroke and relieve any swelling around the brain.
(iii) To detect and treat any delayed complications such as kidney failure, death and destruction of gut tissue.
(iv) To remove the predisposing factors leading to the heat stroke.

Maintaining patent airway is the utmost important part of treatment. The affected dog will be given intravenous fluids and possible cortisone to improve the circulation and overcome any shock that may be present. The dog will be cooled down to at least 39.5⁰C within the first 10 minutes. It is normally achieved by immersing the dog in a cool bath and applying alcohol to the groin and armpits. In cases where the temperature does not lower with this treatment a cold water enema or an ice bath for a very short period of time will be given. In case when the dog is seizuring valium is often given to sedate the dog.
 
The dog's condition is monitored thoroughly once stabilisation is achieved. The dog is placed in an air-conditioned, low humidity environment. The body temperature is constantly monitored to ensure it does not get too high or low. The dog is rehydrated and its urination pattern is observed to ensure that kidney failure does not occur.

As heat stroke is a serious but avoidable problem, dog owners must aware of it as the days get warmer over summer, especially when the days rise over 35⁰C. The following may help to avoid the problem:

(i)   Do not leave dogs in closed cars with no air circulation on warm days.
(ii)  Consider keeping dogs inside the house on hot days, especially if the air-conditioning is turned on.
(iii) Ensure adequate shade is provided for dogs.
(iv)  Ensure adequate water is available for dogs at all times.