Heatstroke is the result of the inability of a dog to dissipate heat. This can occur due to exposure to high ambient temperatures. Dogs do not sweat as humans do as they only have a small number of sweat glands in the pads. They can only eliminate heat by three main mechanisms, which are: panting (which predominates and is characterized by the typical rapid open mouth breathing), conduction (dissipating heat through areas of small amount of hair, like contact of the belly with a cold surface) and convection (the movement of heat energy over the surface of the body).
Heatstroke in dogs
When heatstroke occurs, body temperature increases faster than it can be dissipated. As the temperature increases in the body, which can increase to up to 42ºC (a dog’s normal temperature is around 38-39.2ºC), there is an increase in the levels of some inflammatory substances in the bloodstream. Eventually, these substances will cause injury to multiple organs which will manifest with the signs that we observe in our pets.
Consequences of heatstroke in dogs
Clinical consequences of heatstroke include fast heartbeat (and abnormal heart rhythms), respiratory problems, kidney failure, neurological problems (due to damage to the nervous system) failure of the clotting system (excessive bleeding or clotting) and gastrointestinal problems (vomiting and diarrhoea). These effects can be temporary or permanent (and therefore cause an irreversible damage) and can ultimately lead to the death of the animal.
Dogs at increased risk of heatstroke
- Brachycephalic breeds (such as Bulldogs, Boxers, Pugs…). Due to the conformation of their face, they have smaller air passages and a thick palate which difficulties air flow and therefore heat loss.
- Older, large, and obese dogs and dogs with thick haircoat.
- Dogs with existing respiratory or heart problems
Conditions that are ideal for heatstroke
Situations that may create the conditions for heatstroke are:
- Warm and humid environments (especially if exercise is carried out during the hottest time)
- Closed environments with poor ventilation.
- Leaving a dog in the car (the temperatures in a closed car exposed to direct sun can exceed 48ºC even with an outside temperature as low as 24ºC, this can happen in less than an hour and can be fatal).
Early signs of heatstroke in dogs
If you suspect that your dog could be suffering from heatstroke, early signs may include:
- Excessive panting (and fast, heavy breathing).
- Difficulties to move (or weakness).
- Lethargy and abnormal mental response.
- Bright red (or blue) tongue and gums.
- Excessive salivation.
- Gastrointestinal signs such as vomiting or diarrhoea.
How to avoid heatstroke
- Never leave a dog in a closed car in a sunny day, even with the windows open.
- Avoid walking or exercising your dog in the hottest time of the day, go out early in the morning and evening.
- Always provide free access clean, fresh water. You can add ice cubes to keep it cold.
- Avoid walking dogs on hot pavements or sand to avoid burning the paws
- Allow access to wide and ventilated spaces with shade.
- Allow dogs to get damp in water sources.
What to do if you suspect your dog is suffering heatstroke
- Keep calm to act quickly and efficiently and contact the nearest emergency veterinarian to inform of the situation and initiate transport.
- While transporting your dog, wet the fur, feet and abdomen with cool but not extremely cold water and use a fan.
- Your veterinarian will provide supportive care depending on the severity of the problem.
Prognosis
The prognosis for dogs that suffer a heatstroke will depend on the severity of the organ damage and therefore acting quickly will give your dog the best chance to recover and avoid permanent organ damage.
