Living in the Mediterranean, although many bask in the Summer sun and enjoy the hot and humid air, it can pose as a real threat and hindrance to our furry friends.

Air conditioners and fans become a given and walking becomes a new routine before sunrise and after sunset.

Many people still do not associate the risk of heat stroke with our companion animals due to the fact that ‘they are used to the weather and acclimatised’ this unfortunately comes at a price which can sometimes be fatal.

Heat stroke is a medical emergency characterized by increases in core temperature to over 41°C with manifestations of central nervous system (CNS) dysfunction.  There are two forms of heat stroke described, classic heat stroke (exposure to a hot or humid environment) and exertional heat stroke, which occurs due to strenuous exercise. This classification is extrapolated from human medicine, in which the aetiology, risk factors and presentation are quite different; for example, classic heat stroke is most frequent in individuals who cannot auto-regulate well (i.e. the young and old) in which heat dissipation is poor, whereas exertional heat stroke is seen in active, generally healthy adults, in whom the excessive heat production overwhelms heat-loss mechanisms.  The presentation of classic heat stroke is often a lack of sweating with CNS dysfunction, respiratory alkalosis and organ dysfunction. Conversely, exertional heat stroke results in CNS dysfunction, metabolic acidosis, severe organ dysfunction and haemostatic complications

Many cases in canine medicine will have aspects of both forms of heat stroke, as heat dissipation in this species differs markedly from heat dissipation in humans. Dogs have very few sweat glands (mainly in their feet and nose), so more than 70% of the total body heat loss is achieved through radiation and convection, but as environmental temperatures approach body temperature, evaporation, primarily through panting, becomes more important.  In high temperatures/high humidity, dogs will hyper-salivate, improving evaporation efficiency, until a critical point, at which elevated humidity renders panting ineffective. In addition, the moist mucous membranes of the nasal turbinates provide a large surface area for water loss and further aid the evaporation efficacy. It is likely a decrease in airflow within the nasal cavity is responsible for the increased risk of heat stroke in brachycephalic dogs.

How to cool hot dogs

While evidence in the treatment of canine heat stroke with water immersion is scant, a recent study demonstrated that in exercise induced heat stroke, immersion in a water bath (at 30°C) was superior to cooling with either a water mat at 4°C, or ambient cooling, with temperatures returning to normal within 16 minutes, 36 minutes and 48 minutes respectively.  Furthermore, in a retrospective study, 26 dogs (48%) were “cooled by their owners before admission”; however, the method and speed of cooling was not documented.  Overall, cooling prior to admission per se did not significantly reduce the mortality rate. However, in many cases, admission was after a significant period of time had lapsed, while survival was 100% in 6 dogs that were cooled by their owners before admission and admitted within 90 minutes. In light of these findings, it is recommended that, unless they are elderly, dogs with heat stroke should be rapid cooled by immersion in cold water, to cool them to 39°C as rapidly as possible. Cooling below this temperature is not recommended as frequently the body will continue to cool and can become hypothermic after treatment.