HEAT & HUMIDITY – THE HIDDEN DANGERS
Siberian Husky ownership in the UK has increased massively over the past 20 years – largely due
to an increase in those breeding Huskies commercially, whether as large scale puppy farmers,
small scale backyard breeders or what I call naïve/ignorant/stupid “pet” breeders (the bloke
round the corner who puts his poor quality bitch to a friend’s poor quality dog for pin money).
Some of these new owners haven’t done their research, can’t cope and eventually either sell their
dog on or give it up to rescue. Others take it more seriously, learn all they can about the breed and
do their best to provide the best life they can for their husky/huskies. This often includes them
deciding to allow their dog to do what comes naturally and run them in harness. This is brilliant
and to be applauded. Increasingly however, we are coming across people who don’t realise that
running their dogs in warm and humid conditions during the UK spring/summer/early autumn
can be extremely dangerous for their dogs’ health and welfare.
The Chukchi Inuit people, who first developed these dogs over thousands of years in NorthEastern Siberia, used them as long distance, endurance sled dogs throughout the winter months,
hunting and fishing wherever game was plentiful. In their hot summer months, the Chukchi
would let their dogs roam free around their summer villages hunting for themselves. The dogs
would not be worked at all in harness during the warmer months.
Most husky owners in the UK take the same approach as the Chukchi and do not work their dogs
during the summer. Indeed, even during the winter, most of the husky racing organisations will
cancel events if the temperature rises above 12º C.
Huskies can cope very well with the heat and humidity as long as they are not expected
to work in such conditions. Working in harness in the kind of hot and humid weather conditions
found during the average UK summer is extremely dangerous for sled dog breeds. Heat
exhaustion can swiftly lead to heat stroke and even death. Heat stroke occurs when normal body
mechanisms cannot keep the body's temperature in a safe range. Animals do not have efficient
cooling systems (like humans who sweat) and get overheated easily. A dog with moderate
heatstroke (body temperature from 104º to 106ºF) can recover within an hour if given prompt
first aid and veterinary care (normal body temperature is 100-102.5°F). Severe heatstroke (body
temperature over 106ºF) is seriously life-threatening and immediate veterinary assistance is
necessary.
Why are sled dogs so prone to heat exhaustion? – because of the heat built up during strenuous
exercise. After all, not only are these dogs running, but they are running pulling a sled/scooter/rig
and heavy passengers. Their muscles are able to convert some 20-30% of the chemical energy
they use into mechanical work. So, 70 – 80% of the energy produced by an intensively working
dog ends up creating body heat. During intensive pulling there is a large quantity of heat
generated by sled dog muscles that must be dissipated.
When muscles get too warm, they function less efficiently. When a dog's body warms too much,
its non-muscular body functions not only work less efficiently, but actually may fail entirely, thus
presenting a life-threatening situation to the dog.
As mentioned above, sled dogs can't sweat. If they did, they could improve their rate of exercisecreated heat dissipation through their skin surface. Instead, it is by increasing their breathing rate
and the discharge and evaporation of water from their mouth area that sled dogs can increase the
amount of heat dissipated during exercise. However, the hotter the outside temperature, the less
effective heat dissipation becomes. Atmospheric temperature air is drawn into the nose and
mouth and -- via the air passages -- ends up in the lungs. In winter conditions the cool, dry air is
warmed to body temperature traversing the air passages to the lungs. The air exiting the nose and
mouth from the lungs is warm, moist air close to body temperature. On a frosty day, if the air
entering the mouth/nose is at around 30º F and it takes heat from the body before being
expressed at body temperature (optimally 103º F) it is obvious that heat is being dissipated
effectively. On a humid summer day, with atmospheric temperatures of say, 60º F, the amount of
heat and moisture that the dog’s breathing can take from the body is much less with the result
that heat builds up in the body and the dog’s core temperature can very quickly rise to dangerous
– even life-threatening levels.
Not only that, but a dog which has suffered heat stroke on one occasion, even if it has apparently
been lucky and survived the experience, is likely to be much more likely to suffer the same
problem in the future – the trauma having permanently damaged its thermoregulatory function
and lowered its threshold of tolerance for working in warm conditions. This will make the poor
dog pretty much useless as a sled dog from that point on.
Terry and I have personally been involved in treating sled dogs (not ours) with heat
exhaustion even in mid winter in the UK . For us, the thought of running dogs during the
summer months is way beyond common sense and is not a risk we would take with our precious
dogs. A simple rule of thumb is this – if it is warm enough for you to take your dogs out without
wearing a sweater or jacket, it is too warm to run them in harness.
Mick Brent
Dreamcatcher Siberian Huskies
The Siberian Husky Welfare Association (UK)