Dogs in Hot Weather

Published on 26 July 2020 at 18:24

Back in 2018 I read an excellent article in Our Dogs by Professor Steve Dean on dogs in hot weather.   It was so informative that I contacted Steve and asked if I could share it here on this site for all of you lovely dog moms and dads.  I as thrilled when he not only agreed but sent to me two articles but here is the first one.  I hope you find it as useful and informative as I do and thank you Steve for your contribution; you're the best!


I will publish Steve's second article next month on canine hyperthermia.


Health Matters

Health matters is taking a break from parasites this week to make a few comments about the very warm temperature we are experiencing at the moment and a few pointers on how to deal with it. This is prompted by the burgeoning comments about dogs in cars and watching various folk walking their dogs around shows with smart, well soaked, fitted jackets.


Wet towels and soaked jackets

Taking the wet jackets issue first. The good news is they probably do no harm when used in the open air but they are equally unlikely to aid a dog very much in controlling body temperature during hot weather. This might astonish dog owners but the science is fairly convincing.


Draping a soaked cloth over a dog to aid cooling relies on the well established physics of latent heat and its association with water evaporation. The energy needed to cause water to evaporate draws heat from the local area and in theory cools the surface beneath the wet garment or towel.


Nothing wrong with that, but under the jacket there is a dog’s coat, a very good thermal insulator. Most dogs have good coats to such an extent that the cooling effect of evaporation is unlikely to have a significant effect in cooling the skin. In short water evaporation from the jacket is cooling the surface of the dog’s natural coat.


Add to this the fact that the biology of dog skin is very different to human skin. There are very few sweat glands in canine skin and the blood vessels within the dermis of skin are not designed to be a major factor in body temperature control. Said concisely, dogs do not loose much heat through their skin and coat.



Different physiology

The situation is quite different for man. Human skin has little surface hair and wet clothing will chill the skin and tends to reduce body core temperature as water evaporates. Even the drying of a dog’s natural coat after a swim will have a much lessened cooling effect compared to human skin, thanks to the thermal insulation provided by the canine coat.


Dogs control their body temperature in hot weather through panting and thus a dog with access to drinking water, a cool breeze and shade will be able to control its body temperature very effectively by simply panting. The panting mechanism utilises the cooling effect of water evaporation from the tongue, which in turn cools the underlying plentiful blood supply in the mucous membranes in the oral region.


Muscle activity will raise body temperature quite rapidly and thus panting will increase when the dog is moving. Excess activity may overwhelm the heat loss mechanism and create problems with heat stress. All of this can happen even when wearing a wet towel or soaked garment.


High levels of humidity will also interfere with the panting mechanism, just as it does with our own heat loss system based upon sweating. So humid weather reduces the efficiency of panting or sweating making it harder to keep cool. Being dressed in a wet towel or garment in an enclosed space is likely to raise humidity.


How to keep dogs cool

So the solution to keeping a dog cool is simple - use shade, encourage the dog to relax and lie still and find a breeze if you can (a fan will do just as well). Do not allow humidity to rise artificially through restricted ventilation (by enclosing the dog in a box or solid walled crate for example). Avoid leaving your dog in direct sunlight, simply because this increases the temperature of the air the dog is breathing.


Dogs in cars

So this takes us to the issue of dogs in cars. The traditional warning to dog owners has been simple - ‘Do not leave dogs in hot cars’ This simple message has been altered to be more shocking - for example ‘Dogs die in hot cars’ but now it would appear the message has been hijacked and so now the message seems to have become - ‘do not leave dogs in cars’.


This is an escalation of a simple message beyond its useful meaning. It is also often impractical and a deviation from the science behind the original warning. Leaving a dog unattended in a car is always a risk but this does not mean the end result of keeping your dog in a car has to be poor welfare.


Dogs can be kept in a car in hot weather if some basic rules are obeyed, park in the shade, establish good ventilation and avoid creating an environment where humidity is artificially raised (i.e. leave doors and windows open).


For example dogs kept in an open-sided crate, in a car with the tailgate open and, if available, the sunroof open are likely to be in a good environment assuming the car is parked in shade and there is a breeze. Variations of this situation are also very likely to be effective but the dog owner needs to take responsibility for monitoring the situation and ensuring a dog’s welfare needs are met. This would include regular access to water as dogs need water to pant efficiently.


Common sense

Leaving a dog in a hot car is not acceptable but monitoring a dog left in a car on a hot day alongside adequate provisions to make sure the environment is suitable should not be considered unacceptable just because it is a dog in a car. Indeed to prove the point, the same comments apply to being left at home, in a tent or in a crate or box by the ringside.


Treating hyperthermia

A final word or two about the treatment for correcting hyperthermia in dogs. Frankly it is not rocket science and the message is simple - Get the dog cooled down as quick as you can.


Rapid cooling has risks but so does a high body temperature. Do not make matters worse by messing about with wet towels and spraying water in the mouth this only delays the much needed action.


If you have a dog suffering hyperthermia do one of two things, provide it with cool water to stand in or lie down in or, run water from a hose pipe over part of the dog’s body until it is breathing normally. A personal choice is running water over a dogs hind quarters but total body immersion in water is fine too. Once the coat is soaked the water will cool the skin and therefore the dog but it will take a little time.


With dogs that are only just beginning to suffer the effects of hyperthermia, resting in a chilled environment such as an air conditioned car or room with plenty of drinking water works fine.


So the plea is please let’s stop complicating the risk of hypothermia it does not need an essay to explain it nor a long list of ‘do this’ and ‘don't do that’. The objective is simple, so its keep the actions simple too.  Cool the dog down, do it efficiently and seek expert advice and do it in that order. 

Contact me with comment, argument and ideas for articles by writing care of Our Dogs or by email to stevedean@tyrianborder.

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