08/31/2026
RUNNING DOGS • HEAT TOLERANCE: Understanding the dog & the real factors
A recent question in regards to running with dogs...
"Does anyone know of an app that looks at temperature and humidity to say when it is ok to run with my dog?
I understand it is very dog dependant but I am new to this, so I need some starting point."
With these types of questions people then often reply with so called "safe" numbers, charts, or formulas, particularly in the dryland world.
We'll focus on running dogs in harness as it often comes up especially for Canicross as that is so popular and accessible now, plus I recently was asked to write something about this.
Also, and worryingly, a comment also advised a beginner... "don't worry, it's not hot enough for a dog to overheat."
It doesn't need to be what many consider "hot", hot is relative and all this applies to any form of exercise or work.
The reality is there is no such thing as a specific temperature, a chart or formula that can tell you it is safe for all dogs, there are too many variables.
I'll try to explain the why, or atleast give the beginners or those not sure a place to start, what you need to consider, and then at the end a better way to evaluate when the risk increases, notice I say "risk" and not "when it's safe", think of it as degrees of risk.
Try to get out of the mindset that there is a safe temperature, these working dogs can overheat in temperatures below freezing. There is a LOT to heat tolerance, which is why this is a long post.
● Specifically in the UK years ago when I started there was a narrow window in which we were running sled dogs most of the time, typically between 0 - 10°C (32 - 50°F), sometimes lower, occasionally it would creep up through the winter and racing season, but not often.
Some would not run their dogs over 10°C, a few would with caution, but back then I'd never seen or heard of dogs overheating, unlike today.
These days it is much more varied, the season is not as cool as it used to be, it's often shorter in terms of cooler temperatures, it's a real treat if we get snow on the ground and minus temperatures.
Spring is prime time for heat injury due to the sudden increase and fluctuation in temps, most of the dogs I've seen get in trouble was around March, but it's not confined to this time, dogs overheat all through the year, October, November, time of year doesn't matter.
These days with the popularity of Canicross, and to some extent Bikejor, it's much more accessible to those with one dog, particularly with Canicross you now have many different breeds, with owners and dogs of varied abilities.
Unlike with sled dogs where people new to it often have guidance from the more experienced, those starting for the first time running with their pet are sometimes starting from scratch, with no guidance, figuring it out as they go along.
And Canicross dogs can be running in warmer temps, sometimes a lot warmer.
Temperature cutt-offs are typically different for Canicross vs Bikejor and Rigs.
But having said that, it's often the more experienced who's dogs overheat!
Being out on the trail with a canine heat casualty, limited resources, no help, and no experience dealing with it is not a position you want to find yourself in, and people do run dogs in places with limited water or means to cool a dog down. So we want to avoid it!
● 2 things to take into account. The dog's internal heat production because we're talking about dogs working/exercising. And their ability to lose that heat.
These are influenced by the environmental conditions, ambient temp, humidity, shade, sun, wind, and other factors such as the level of acclimation, body condition, conformation, fitness/conditioning, intensity of exercise, hydration, coat, excitement, drive and the dog's lack of self-preservation.
Below we'll look at these things closer.
● Formulas - there are variations on this but a popular one is... add the ambient temperature and humidity together, if it totals 100 or above then don't run.
Like charts they take into account nothing in regards to the individual dog and all the factors involved. Some people will also change that number to suit. They are also dependant on whether your're using Fahrenheit or Celsius.
Another issue is location, you can get different results in different environments, for example in the UK it's not uncommon to have a summers day at 1pm with 25°C and 34% humidity = 59, well within 100!
Or a cool 6am morning at 11°C and 95% humidity = 106.
See the problem? According to this, run your dog in the hottest part of the day (the result will be different elsewhere).
I've also seen dogs overheat in those morning conditions.
● Charts - The photo shows 2 charts, well it's actually the same chart used by 2 different race organisations, one in Australia, one in the UK.
The issues:
• 2 countries on the opposite side of the world, the dogs in each country are acclimated to those 2 different environments, so you can't realistically think a chart for Australian dogs is suitable for UK dogs.
• Charts cannot take into account individual dogs, the dog's body condition, fitness and level of conditioning, hydration status on the day, level of acclimation to the conditions on THAT day of running. These things are super important.
• A dog running at 10°C will have a vastly different experience at 30% humidity vs 90%, this is what the chart is trying to account for, but it's just one factor.
• The central shaded areas take into account ambient temperature and relative humidity to give an "Apparent temperature":
Green - Full distance recommended
Yellow - Shortened distance recommended
Red - Do not run
Clearly if you don't run in the red zone your dog is safe from that point, the problem is the green zone doesn't mean it is "safe".
A common answer to this is "use common sense", this has got to be the most useless answer to anything heat related when the people you're trying to help/educate don't understand in the first place!
"Know Your Dog" is the other answer, and this is absolutely true... we'll come back to what this means.
• I'm not saying don't use these methods (even though I wouldn't), because people tend to get upset when you tell them what to do, or not to do, I have no desire to upset anyone, just to help people look after their dogs.
.........
● The factors charts etc cannot account for:
• GENETICS - I've heard it said "dogs can either handle the heat or they can't, it's as simple as that". I'd say it's partly true in that some dogs genetically have a better heat tolerance than others, some mushers have selected dogs for superior heat tolerance to run in their teams, breed dogs with superior heat tolerance and do have lines with superior heat tolerance. Every dog is different, every dog has a limit.
You can improve heat tolerance to a point with conditioning, acclimation, etc.
• ACCLIMATION is a huge one. The same dog may struggle more with 10°C (50°F) in Spring but be fine with the same level of effort with 10°C once they've had time to acclimate.
How long does it take for your dog to acclimate to increases in temps?... Depends who you ask, and again the individual dog and how you're doing it.
In the working dog arena it's often said 2 weeks, there is also research to suggest dogs show improved tolerance after just a few days in the population of dogs that were studied, pet owners are often told anything from 30-60 days.
Consider a high level, well conditioned dog, with consistant training is likely going to acclimate faster than the weekend warrior. And to acclimate to changes in temps you need to train in those temps.
So, how well acclimated is your dog to the temps within the chart?
Or more important, how well acclimated is your dog to the conditions they a running in THAT day?
• FITNESS/CONDITIONING is huge, a trained dog with a higher aerobic capacity or VO₂max can handle higher temps much better than if untrained.
• INTENSITY - how hard your dog is working makes a huge difference because the harder they work/the faster they run, the more heat they produce, heat they need to get rid of. "Running" is a loose term, a dog trotting on a steady run in temps that are increasing can handle it better than a dog in a full out sprint at close to max effort. So a dog running at higher intensity can't handle the temperatures it can at lower intensity. Some dog owners will say "but my dog has only one gear/speed, full speed, he's a nutter", if you can't slow your dog down when temps/humidity increases you have to factor that in to your decision.
We need to understand factors to help dogs manage the heat they produce, knowing that it's gonna be produced.
• HYDRATION is super important, dehydration decreases heat tolerance, even 1% dehydration can negatively impact your dog's ability to cool. Dehydration lowers blood pressure and cardiac output making it harder for them to push blood out to where it can be cooled off, panting is reliant on the evaporation of water, and once it gets to a certain point they then hold on to water at the expense of higher body temperature. At events where there are vet checks, there is a reason they check hydration status before you run. Charts etc cannot account for your dog's hydration status.
• THE HUMAN ELEMENT - competition, the desire to do well, ego, overestimation of the dog's fitness, lack of knowledge... all can increase risk.
• STRESS - for both the human and the dog, the added stress of a race environment vs the more relaxed (for some) training environment or recreational run.
Look after yourself, if not you may not make good decisions for your dog.
• HOW is the temperature being measured? Is humidity being measured? It's not uncommon for race organisers to measure only the ambient temperature in the shade at the startline, not taking into account the rest of the trail, or even humidity.
If you do it yourself, how are you doing it? Are you using a weather app? Which may not be the same as where you actually are. Then there are the micro-environments within your location.
Also, measurements are generally not taken at the dog's level from the ground, around 20 inches vs average human head height of 5-6 feet, for example humidity can be a lot higher lower to the ground at the dog's breathing level, even withing that short vertical difference, this vertical variation is a feature of localized micro-environments.
• WBGT (Wet Bulb Globe Temperature) is becoming more common these days, it takes into account not just ambient temp and humidity, but also wind and solar heat from the sun to give a better account of how the conditions affect us, there are guidelines for humans and horses but not dogs. Devices for measuring WBGT are not available to everyone due to cost, you can look at the "feels like" temp in weather apps, but again consider whether they are accurate to your location.
Most people are going to use ambient temp and humidity.
Whichever metric and method you use stay consistant but understand the numbers on their own mean nothing without context, you still have to understand your dog's current level of acclimation and how changes affect your individual dog, so you can understand how the numbers relate to your individual dog.
This is not about "hot weather", what your dog is acclimated to is more important, although every dog will have a limit. For dogs acclimated to minus temps, zero degrees can be too hot!
• MUZZLES - these can affect a dog's ability to cool through panting which is critical when exercising, how much depends on the muzzle.
Muzzles are controversial, there's nothing wrong with using them as such, some people do use them especially in Canicross, it's good to muzzle train dogs, but there are important things to note. Pant room is super important, they need to open their mouth fully to pant and lose heat, but it's not only about pant room, the tongue is also important, the issue is even basket muzzles with a so called "full pant room", depending on the dog often don't allow the tongue to fully hang out, so the level of increased risk with muzzles is directly related to the individual dog, the conditions you run in, and the intensity you run at, remember the higher the intensity the more heat being produced.
So depending on these factors you may have to be even more aware of the temp and humidity you run in, and the intensity you run at.
Or think of it like this... the temperature limit at which your dog can run at, and the intensity at which your dog can run at with a muzzle may be lower than without the muzzle.
• "If in doubt, don't go out"... "If in doubt, don't run" are also common terms, good advise, but the problem is people are not always in doubt, they follow the chart or formula, it says it's safe to run, or that's how people interpret it. They are in no doubt, they think it's safe so they run, they don't fully understand and they get caught out.
Most dogs running are not overheating in the heat of summer, because most people are not training in those conditions. Dogs overheat in cooler conditions, people don't expect it, they get caught off-guard.
• So now we have to go back to what keeps dogs safe in the first place... knowing the dog in front of you, reading the dog, understanding the dog and what they are telling you, and all the factors involved, you can't get away from it.
• No chart, formula, or person that doesn't know your dog can tell you it is safe to run your dog.
• People want an easy way to evaluate when it's safe for any dog.
A chart or formula that answers the question... it doesn't exist.
• Some people will tell you they use these methods and they've always worked. But their dogs are different to your dogs, you can't judge what is safe for your dog based on what others are doing, and for the beginner that can be dangerous.
• BUT... "we need somewhere to start"... we'll come back to that.
.........
● "KNOW YOUR DOG" is a term that is out there now, and you should know your dog, but what does that really mean? How does telling the beginner "you need to know your dog" help them when they don't understand?... It depends on the context...
1️⃣ For health and emergency care it's good to know your dog in terms of vital signs, your dog's normal resting and working heartrate, respiration rate, resting and working body temp, CRT, MM colour, assessing hydration status.
2️⃣ For heat, knowing the signs of thermal stress, heat stress, such as how panting changes, controlled vs uncontrolled panting, tongue shape and length, behavioural signs, mentation, etc.
Those things are good to know, they don't help you in the moment when your dog is running out front but they can help if you stop for a break to check on your dog, or after the run.
3️⃣ In our case knowing your dog while running is the most important because the earlier you catch a potential problem the better, being able to read them, think of it as real time feedback. If you're new to this or have not thought about it before start paying close attention to your dog while running, observe them constantly, you're not looking for a problem as such, you're looking for information, what the dog is telling you.
For instance, be aware of...
• Their Enthusiasm
• Is a dog running how he normally runs or is something off? For that you have to know what their normal is.
• A change in Tail-set
• A change in Ear-set
• A change in Gait
• How is their Gait at different speeds?
• Look for water/head dipping?
• Is a dog not listening to you?
• Are you not getting a response when you normally would if you call the dog's name for example? Could be something as subtle as an ear twitch
• Are lead dogs not listening to commands, missing turns or hesitating?
• If you think a dog is playing around or not concentrating, is he? or is he getting hot?
• Slowing down is an obvious sign but dogs can push themselves too far before they slow
• If running multiple dogs are any necklines tight? Tuglines loose? Dogs changing position? Is a dog struggling to keep up with the others?
• Be aware of anything out of their normal, for that you have to know what their normal is, while also bearing in mind high drive dogs may hide early signs while in drive, and it's not until they come out of drive they will be more visible. It's important to catch any signs early to stay ahead of it.
.........
● Back to "We need somewhere to start"
Here it is from Dr. Janice Baker (Veterinary Tactical Group)...
"The main risk factor for heat injury is a rapid change in the ambient temperature, humidity, of the dog's environment...
So the primary risk factor is, is your dog prepared to be in the temperature that it’s going to be today? And a really simple way of sort of estimating that is, look at the average high temperature for the last two weeks, and the average high humidity, and if there’s going to be a 15°F [8°C] change, or a 15% humidity change, then we know your dog’s more at risk. And that’s a simple thing that anybody can calculate. It doesn’t mean don’t work your dog, it just means you have to be extra cautious and cool him down a lot during the day and things like that...
I get a lot of inquiries through email or just questions when people say, you know, we want to make some kind of chart, like when, at what temperature should we stop and rest? The thing is, it depends on your dog’s acclimation and it depends on the individual dog within that environment.
I worked on a lot of sled dog races up in Alaska. And I remember this one particular day, it was five degrees above zero fahrenheit, and with the windchill it was 25 below. I couldn’t feel my face. My feet were frozen and I was all done up in an Arctic suit. I should have been fine. I was just miserable. And it was right after the sun came up which was about 9:30, 10 o’clock in the morning. And this team came in off the trail and and we always go up to the mushers and ask how their dogs' doing. And he said "I’m gonna rest my dogs they're getting really hot." I can’t feel my face and your dogs are hot? Well they were dogs that lived up above the Arctic Circle, and they’re used to subzero temperatures. So they’re used to living at 10 below or 20 below over the winter. And it’s five above. That’s too hot for those dogs. And that just blew my mind. It’s not the ambient temperature. It’s what the dog's used to. And if you can have a dog heatstroke at 5°F [-15°C], while I’m dying of hypothermia.
It’s all about what you’re acclimated to."
● More from Dr. Baker...
"The most consistant thing available to anybody to prevent Heat Injury in your dog is to train and acclimate your dog AT or ABOVE the expected level of exercise."
"One of the most important preventive steps you can take with heat injury is to have a well-conditioned, physically fit dog that is acclimated to the temperature of the environment he is working in THAT DAY."
"One sign of a good handler is their ability to “read” their dog."
"Handlers can-and-should- also learn to read the signs of increasing thermal stress to help prevent their dog from becoming an actual heat injury."
"Behavioral indicators of thermal/heat stress are an important form of communication that we have to be attuned to receiving and understanding from our dogs."
"Recognising Thermal Stress... that's the biggest prevention you can have... "
"We're trying to teach the behavioural signs of thermal stress, we don't call it heat stress 'cause heat stress is a term for a low grade of heat injury, thermal stress is normal, if your dog works hard he's gonna get hot and his body's equiped to handle that to a point, so we say look for things... "
.........
● In Summary:
So now you have a better understanding of the factors that influence safety, or risk.
To keep it simple...
1️⃣ Pay attention to the temp and humidity, look at the average high over the preceding 2 weeks, if there is an increase then understand your dog is at increased risk, your dog may not slow down themselves, but they will have a harder time compensating.
You can reduce the risk by shortening the distance, decreasing the time, decreasing the intensity, giving more frequent breaks to let them cool down.
2️⃣ Know Your Dog. Learn the signs of thermal stress, learn to read your dog and what they are telling you in the moment, it takes time, work with your dog, observe constantly, it will come.
If you don't understand the dog in front of you, in the moment, if you don't understand what is normal, then you can't understand what is abnormal, then you are just rolling the dice, taking a gamble.
3️⃣ Over time working with your dog and understanding these things, and paying attention to the conditions you train in you will get to know what your dog can handle.
4️⃣ Lastly - It's okay to not understand all this in the beginning, everyone started somewhere.
.........
● Further Information:
> How do you really prevent Heat Injury/Heatstroke?
https://www.facebook.com/share/v/1BbnUPWuQ8/
> Early signs of increased Heat Stress while running
https://www.facebook.com/share/v/1F4GgBpuMx/
> POP QUIZ
https://www.facebook.com/share/p/1BDLFh5Yiz/
> Reading Dogs 👀
https://www.facebook.com/share/p/16dNj9VTDc/
> When is it Too Hot?
https://www.facebook.com/share/p/1AtYewRa3E/
> Differences in Heat Tolerance between dogs and factors to consider
https://www.facebook.com/share/191smCxK4o/
> Humidity
https://www.facebook.com/share/p/1D3vUz6gCc/
> Acclimation (and how I apply it with my own dog)
https://www.facebook.com/share/p/1J9iBaULvK/
> Hydration Index 💧
https://www.facebook.com/share/p/16pkWpw68f/
> Someone asked a great question...
https://www.facebook.com/share/p/1AxoWikGKg/
