Before we start talking about heatstroke, let’s review the physiological mechanisms of body temperature regulation in animals.
Characteristics of thermoregulation in dogs and cats
In humans, the mechanisms of sweating and sweat production play an important role in thermoregulation. The sweat glands of dogs and cats are different and secrete a so-called greasy sweat, which has a denser consistency and is therefore virtually odourless, and whose main function is to impart waterproof properties to the coat. Greasy sweat also has a secretory function, but is largely absent from the thermoregulation process.
In dogs and cats, the main moisture that lowers body temperature evaporates through the tongue and the mucous membrane of the mouth. As body temperature rises, animals begin to breathe more densely to increase heat transfer. If the normal respiration of an average dog the rate is 20-40 breaths per minute, which can reach 400 breaths as the temperature rises.
What is heatstroke?
Heat stroke is a pathological state of the body where the body temperature increases due to high ambient temperature or due to increased heat production by the body through reduced heat transfer, for example during exercise.
Heatstroke usually occurs when an animal is enclosed in a hot car or left outside on a hot sunny day without shelter. Heatstroke caused by physical stress is less common, but can occur in dogs trained in hot humid weather or in animals with impaired heat release.
Factors that increase the fidelity of heatstroke:
Brachycephalic breeds: bulldogs, pugs, pekingese, etc;
cats of breeds such as Angora, Persian, Exotic, etc;
upper respiratory tract pathologies causing obstruction: tracheal collapse, tracheal or laryngeal tumours, foreign bodies, inflammatory processes, etc.;
cardiovascular disease, where there is reduced blood flow and a rise or fall in blood pressure;
kidney disease;
obesity;
dehydration;
coat condition and length;
the age of the animal;
high humidity.
Clinical signs of heatstroke
The first signs of heatstroke are increased respiration and heart rate, which occur as compensatory mechanisms to increase heat transfer. At the same time, the ventilation volume of the lungs does not change, but only the ventilation of the upper airways increases, resulting in increased evaporation of moisture from the mucous membranes, which dries them. The rapid heartbeat delivers more blood to the peripheral tissues, which again contributes to heat transfer. Visually, this is manifested by reddening of the mucous membrane.
The animal becomes restless, unable to find a place for itself. Weakness develops further, the pulse weakens, the CNS depresses to the point of shock with unconsciousness. The mucous membranes, which are bright red at the initial stage of heatstroke, become lighter in colour and cyanosis may occur. As an internal organNausea and diarrhoea are possible.
Rectal temperature rises above 40 C during heatstroke and may reach the critical threshold of 42 C. At this temperaturel breakdown of proteins begins in the body, and if the temperature continues to rise, irreversible changes in the vital medulla oblongata, muscles, liver, and intestines begin, leading to coma and death.
First Aid for Heatstroke
The first step is to cool the animal’s body and remove the factors that caused the heatstroke. The animal should be placed in the shade, preferably with the back of the head slightly higher than the head. This will increase blood flow to the head and heat transfer. If the animal is conscious, give it a drink of water.
The animal’s fur should be wet. You can wrap it with a wet sheet or towel, use ice as a compress on the head. Rubbing the bare areas of the body (armpits, paw pads, groin) with alcohol or vodka is effective. However, this must be done outdoors and the animal must bein the shade, as rubbing in the sun will only increase the animal’s body temperature.
Check the rectal temperature every 10 minutes and do not cool the animal when the body temperature reaches 39.5 reC, as this will cause chills which will cause the temperature to rise again.
After first aid, the animal should be shown to a veterinarian to avoid complications that may occur several days after impact.
Prevention of heatstroke
The main prevention of heatstroke consists in the timely elimination of the causes that may lead to it.
During heatstroke, the animal should not be confined in a small, unventilated room or machine. On a hot day, exercise should be adjusted accordingly and walks should be taken early in the morning or late in the evening. If the animal is muzzled and starts to breathe heavily during the walk, the muzzle should be removed as it restricts the animal from panting and prevents the animal from cooling down.