Unfortunately many dog owners are not fully aware of the possibility of their dog suffering from heat stroke under certain environmental or exercise induced situations. Hyperthermia refers to any situation in which the body temperature of the animal is elevated beyond the normal range. Heatstroke, in simple terms, is when the body temperature of the animal is raised to an excessively high level which can induce multi-organ damage and/or failure and occurs “when heat generation exceeds the body's ability to dissipate heat”.
What is Heatstroke in Dogs?
The body temperature of a healthy dog is kept at a fairly steady level under normal environmental temperatures and normal fluctuations therein by the workings of the thermoregulatory centre within the hypothalamus in the brain. If a dog is exposed to elevated temperatures or is exercising and the body temperature starts to rise, physiological and behavioural processes which will bring the body temperature back to a more acceptable level will be stimulated. In dogs in areas where the ambient temperature is elevated, the body systems will attempt to increase the heat loss from the body via evaporative cooling and radiation of the heat. These processes may include panting, drooling and vasodilation.
Heatstroke however is more than just a dog in a hot environment attempting to cool down by these natural processes. Heatstroke will occur when these natural cooling processes are overwhelmed. Some instances when heatstroke may occur in dogs include (but may not be limited to):
- During excessive exercising in extremely hot weather
- Failure to provide adequate water or shade for a dog during extremes of high temperature, this includes tethering a dog without shade
- When dogs are left in small unventilated spaces during hot weather, notably in cars where the internal temperatures can soar rapidly on hot days
Predisposing factors can increase the risk of a dog developing heatstroke in such circumstances. These factors include obesity, older age, illness, animals with congestive heart failure and brachycephalic dogs are seen to be at increased risk.
Heatstroke Symptoms in Dogs
If a dog is suffering from heatstroke owners may notice some or all of the following symptoms (other symptoms are also possible):
- Elevated breathing rate
- Panting
- Collapse
- Seizures
- Disorientation
- Changes in gum colour or spots on the gums
- Dark brown urine or failure to urinate
- Vomiting and/or diarrhoea
- Symptoms of shock
Heatstroke in Dogs - What to Do?
If the history or physical signs are indicative of heatstroke, the dog must be admitted to a veterinary hospital as soon as possible. Cooling the animal with cool water, not ice, will often be advised where possible if delays are expected in reaching a veterinarian. The use of a fan over the dog will also increase the rate of evaporative cooling. A study of 54 cases of heatstroke in dogs has shown an increased survival rate in all dogs in the study which were cooled by their owners prior to admission and/or presented to their veterinarian within 90 minutes of the heatstroke occurring. Attempts to reduce the body temperature of the animal should be done with cool water, not ice or ice water as they cause constriction of the peripheral blood vessels and this slows the cooling of the internal organs of the body. The use of ice/ice water may also instigate shivering which will increase heat generation in the body, thus further increasing the body temperature.
Heatstroke is a medical emergency. The treatment protocol used by your veterinarian will depend on the severity of the symptoms at presentation and the progression of the situation over time. Heatstroke can lead to multi-organ failure and death. Rapid and aggressive therapy is required to cool affected dogs and correct the dehydration, metabolic imbalances and prevent thermal injury to the body tissues. There are no over-the-counter pet medications that can be used to treat heatstroke. The prognosis for dogs affected by heatstroke often depends on the length of time of the hyperthermia, the time to admission to a veterinarian and instigation of treatment, the normal state of health and age of the affected animal, and the rapidity of response to the treatment instituted.
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How to Prevent Heatstroke in Dogs
The severe nature of heatstroke and its potential to be fatal requires owners to be vigilant with their pets in extremes of hot weather. Prevention of heatstroke centres on avoiding situations in which the dog is exposed to extremely hot temperatures. Dogs should never be left in cars in hot weather, even with the windows down the car’s internal temperatures can rise rapidly. All dogs should have adequate amounts of drinking water available at all times in a dog bowl and the provision of shade at all times or access to cooler areas such as the house should be considered in hot weather. During the hotter months of the year a dog’s exercise program should be tailored to reduce excessive exercise during the heat of the day.
Common sense and advance planning for hot weather can help reduce the risks of heatstroke for your dog.
