All posts by HotDogsCanineHeatstroke

We are a team of researchers investigating heatstroke in dogs.

Dogs don’t just die in hot cars.

Dogs-Die

Hopefully by now, most people have seen the warnings that dogs die in hot cars. They die of heatstroke because trapped within a car, with little or no air flow, they get hotter and hotter. Once their internal blood temperature exceeds 41oC their internal organs become damaged and begin to shut down. This can take minutes.

But hot cars are not the only reason dogs die from heatstroke. Increasingly, hot countries are reporting that exercise is the major reason dogs get taken to the vets with heatstroke. Now in the UK we’ve been lucky.  Traditionally, the UK doesn’t see much hot weather, and when we do, it usually doesn’t last long before we get rain, wind, sometimes even the odd summer snowfall!

But this is changing.  Climate change is increasing the number and frequency of abnormal weather events.  Look at 2018, at home in the Midlands in March it was -7oC. Three months later it hit 32oC on my driveway. Three months is 90 days.  Heat acclimatisation takes around 60 days.  I remember de-icing the car on Easter weekend, so before the prolonged period of heat hit, we didn’t have 60 days to acclimatise to the heat, and neither did our dogs. Already there have been reports of dogs presenting to veterinary practices suffering from heatstroke following exercise, one dog lost their life following a walk in the heat.

Heatstroke happens when exercising dogs get too hot and stay hot.

Dogs and temperature

Unlike horses and people, dogs can’t sweat.

Unlike horses and people, dogs come in an enormous range of sizes, colours, coat types and length, breeds and personalities. Ok, people and horses are also pretty variable, but you don’t often see a x40 difference in body weight like you do in dogs.

Dill hot in mud.jpg

Because dogs can’t sweat, and because they are so variable, there is NO SAFE TEMPERATURE.  In our research we saw dogs reaching a critical temperature (over 40.6oC and up to 42.5 oC when measured with an ear thermometer) at every race we attended over a two year period.  At every race.  Some races it was snowing, the hottest race was 15.4oC. We’ve spoken to canicrossers (people who run with their dog in harness) who have seen dogs collapse from heatstroke with snow on the ground (on-going project so no reference yet!). Yet we’ve also seen dogs competing in long races in the middle of summer crossing the line safely.

There is no easy way to predict which dogs will overheat.

You need to know your dog. Some dogs will tell you when they’ve had enough. They’ll lie down, or seek shade, or just flatly refuse to move! But some dogs will run until they drop, so they need to be managed with exercise only in the cooler mornings and very late evenings.

A cautionary tale

Danny lost his beautiful dog Brodie in June 2018.  The temperature was 19oC. Brodie wasn’t working hard.

[Videos – click the links to view]

WARNING this may be distressing to hear: Danny after Brodie collapsed

This is what he was doing before he collapsed; listen to Brodie’s breathing at the end of this video, something wasn’t quite right: Brodie training

Brodie collapsed shortly after this video was taken.  Tragically he died from heatstroke.

Danny has kindly allowed us to share Brodie’s story, because like us, he would like to see canine heatstroke become a thing of the past.  Heatstroke kills dogs. Veterinary hospitals report mortality rates of up to 63% in dogs with heatstroke.

Your dog won’t die from a missed walk, or run or training session.  If they get heatstroke: flip a coin. Heads you win, tails they lose.

coin toss Stevie.jpg

Dog’s cool in a number of ways.

Like us, dogs have a number of ways to cool down if their core temperature gets too high.

  • Radiating heat into the air around them – the hotter the air, the more humid the air, the less this happens.
  • Conducting heat to their surroundings – if the ground is hot this won’t happen.
  • PANTING! Air in the lungs is moistened, meaning water evaporates as the dog pants. If the dog can’t move enough air, or if the dog is in a humid environment, this becomes ineffective.

So if it is hot and humid dogs will struggle to cool.

But even if it’s cold and dry, if your dog can’t move air, their main cooling mechanism isn’t working.

Panting, some key facts

In order to pant, dogs need to be able to move air.  Anything obstructing air flow, will limit the effectiveness of panting and therefore cause the dog to overheat more quickly (see below for respiratory disease).holly panting (2)

  • Brachycephlic breeds
  • Laryngeal paralysis (see below)
  • Tracheal collapse
  • Any respiratory disease, or heart disease that affects normal breathing.

In order to lose heat through panting, dogs need enough water in their body to moisturise the air.   A dehydrated dog will conserve water and produce less saliva, and not moisturise the air in their lungs as much as a well hydrated dog.  Unsurprisingly, they get hotter quicker when exercising.

  • Vomiting
  • Diarrhoea
  • Anorexia (not eating)
  • Being in a hot environment
  • Urinating more frequently (diseases like diabetes, Cushings, hypothyroidism, renal disease can all cause this)
  • Not being given enough to drink or something nice to drink

Anything that could make your dog even slightly dehydrated could increase their risk of heatstroke if they are exercising. The same as people!

How do I know if my dog has a respiratory condition?

Usually, this is fairly obvious. If you’re sat on your sofa watching television, can you hear yourself breathing? No? Good, this is normal! Noisy breathing happens when there is turbulence in the respiratory tract.  This could be a narrowing, a flap of tissue, or liquids like mucous or pus. Narrowed airways may cause wheezing, or whistles. The classic noise is snoring.  If you can hear your dog breathing when they are at rest (and awake), this isn’t normal.

holly on a beach

However, this isn’t always the case. My family dog Holly (the Goldie here) had laryngeal paralysis (LP).  This is a disease one respiratory specialist vet described as “something that can be diagnosed whilst walking past a dog in the street”. They’re normally noisy.

[Videos – click the links to view]

Extreme laryngeal paralysis – this is an advanced case.

Cyanotic dog with laryngeal paralysis – note the blue tongue!

LP dog at the vets – not so obvious, panting, but listen to the forced exhale.

Holly wasn’t a noisy breather. She panted quite a lot but never made ANY noise.  I am a vet, and I missed it.  She started collapsing on walks. She would go very pale, collapse, and then about 5 minutes later get up and be fine! I checked her, found nothing. Checked her again, found nothing.  Then one day I was there, her heart rate was over 300 beats per minute and that’s not normal! So I referred her to a cardiologist thinking she must have a heart problem, they eventually examined her airway with an endoscope and found her LP. Her diagnosis was made almost by accident.

Because we then knew she had a respiratory problem we were careful with her.  We kept her cool, we kept her walks short, we kept her weight as low as we could. Because of my background, I knew she was at an increased risk of heatstroke, so I made sure she wasn’t put at risk.

If you are worried about your dog, get them checked by a vet.  If they find nothing, but you are still worried, get them checked again.  Don’t be afraid to ask for unusual things.  If your dog’s problem happens during or after exercise, ask if you can walk them in the car park and have them examined during and after exercise.

If you know, or suspect, that your dog is suffering from any kind of respiratory problem, be extra careful. Keep your dog cool in the warm weather and don’t risk exercising during the heat.

wallowing.jpg

Thinking of monitoring your dog’s temperature?

Know your limits!

This applies both to your ability to accurately use the thermometer you have chosen (see below for tips on some of the more sensitive ones), and also to interpret the reading in front of you.

What is a normal canine temperature?

This isn’t an easy question to answer. Google normal dog temperature and you will find a huge variety of temperature ranges reported by various sources.  When you look at the range, does it tell you who established it and in what population of dogs?  So far we have only found one source that answers those questions, and it was a German study, using 62 healthy dogs presenting to a veterinary hospital. The range they suggest is “normal” for a dog in the vets is 37.2 to 39.2°C (Konietschke et al. 2014).  Keep in mind, these were dogs in the vets, so your dog at home in a non stressful environment is likely to be at the lower end of this limit.

Consider your dog’s state when you take their temperature.  Are they excited, have they just been fed, have they just been walked/run/chased the cat, have they just spent the last hour lying in front of the fire?

After exercise, you dog’s temperature could be anything from low (if they got very wet in cold weather), right up to around 42.5°C – this is seriously hot. If you dog’s temperature is over 40°C after exercise, considering cooling them or at least check it again after 5 minutes.  If a dog’s temperature remains over 41°C for any length of time this is when heatstroke becomes a very real (and possibly fatal) possibility.

The options.

If you’re going to go to the trouble of monitoring your dog’s temperature, make sure you understand the risks and limitations of the thermometer you choose to use.

Mercury glass thermometers

These are the traditional thermometers you may remember from science classes at school.  They are rarely used in the UK anymore, due to the very real risk of the glass breaking and mercury poisoning! (Emily – I can remember an order of 10 mercury glass thermometers arriving completely smashed, and having to close the vet practice I was working in for the day, evacuate all staff, clients and patients so it could be professionally decontaminated!)

If you only have access to this type of thermometer, you need to be aware of three important things:

  • Firstly, you’ll need some lube. You can’t ask your dog to hold this under their tongue for a minute, so it’s going into the other end I’m afraid! Forget lubrication, and this is the last time your dog will ever let you anywhere near their bottom.
  • Secondly, once you’ve found some lube, you need to shake the mercury back into the bulb. Otherwise you won’t know if the measurement you get is today’s temperature, or the last temperature recorded.
  • Finally, you do need to leave them in for at least a minute.  Remember there is risk of breaking the glass, so seriously consider if this type of thermometer is worth the risk.

glass thermometer

Digital predictive thermometers

There are now far more common in both human and veterinary practice.  The major advantage of these thermometers is speed.  Not as accurate as simple digital thermometers (the hints in the name, predictive), but readings usually in under 10 seconds.

If you are looking for a cheap, reliable, safe and accurate option for monitoring temperature, this is your best bet.

Things to remember:

  • I’m going to say it again, LUBE.
  • Often these come with disposable plastic thermometer covers to help reduce disease transmission.  It’s up to you if you want to use them, single use plastic waste should be avoided where possible, so if you opt to go down the sustainable route remember to disinfect your thermometer after every use.
  • If you can, go for the models with a flexible probe, if you dog sits down, they’ll thank you!

 

Ear thermometers

So far, we’ve found these to be the best alternative to rectal thermometers in terms of both accuracy and tolerance.  You do need to use a veterinary model, so thats either the Vet-Temp or the Pet-Temp, which means you’re looking at around £100+ for the thermometer and you definitely need a supply of probe covers.  Ear wax completely blocks the thermometer’s sensor so you can’t scrimp on using a new probe cover each time I’m afraid.

Ear thermometers are not as accurate as rectal thermometers.  There are more things to go wrong: correct positioning, ear wax, hairy ears.

If you are going to use an ear thermometer, train your dog to accept ear handling and gradually introduce the thermometer.  We’ve found most dogs tolerate the thermometer really well, but it does beep loudly.

Also, if you’re going to use an ear thermometer, use an ear specific normal temperature range.  We suggest 36.6-38.8°C (see references below).

FINAL Rectal vs tympanic membrane temperature in exercising dogs

Link to published version

FINAL Establishing a reference range for normal canine TMT

Link to published article

IMG_0754
Monty the dog having his ear temperature taken

Non-contact infrared thermometers (NCITs)

If something sounds too good to be true, be wary.  Human medics and nurses have found these thermometers to be both accurate and safe, reducing the risk of disease transmission between patients as they require no physical contact with the patient. Sadly so far the situation in veterinary medicine is very different. Animals are typically covered in fur, so obtaining an accurate temperature by measuring the animal’s skin surface temperature isn’t currently possible.

So far papers have explored using the eye (Kreissl & Neiger 2015), various anatomical sites including the ear, gums and hairless skin near the rectum in cats (Nutt et al. 2015) and the muzzle and forehead regions in dogs (Omóbòwálé et al. 2017). None of these papers support using NCITs in a clinical setting.

We have just finished a study comparing NCITs to rectal temperature in cats and to ear temperature in dogs, watch this space for the final results!

Leo NCIT 2
Leo the cat having his eye temperature measured with a non-contact thermometer (the Rycom device)

Temperature sensing microchips

Underused in my humble opinion! No, they don’t report the same temperature as a rectal thermometer, but guess what, a rectal thermometer doesn’t report the same temperature as blood temperature so it’s a compromise (Greer et al. 2007).

To me, your dog legally has to be micro-chipped (UK), why wouldn’t you have one that gives you the option to also monitor temperature?

You can pick up a temperature reading microchip scanner for around £55 on Amazon (Halo scanner) – incidentally, if you travel with your dog, this is worth buying anyway, with your own chip scanner you can check your dog’s chip is reading fine before you set off, and if you pack your scanner you know you can locate it at customs should they have a problem! The Halo scanner has the added benefit that if you regularly connect it to the on-line database, if you scan an animal reported as lost or stolen, this will flash up when you scan the chip. So if you regularly come across lost dogs, having one of these in your car can be useful.

These scanners are really easy to use, you just squeeze the handle (where it says Halo), wave them over your pet’s chip, they beep when they’ve found it and display the temperature.

halo scanner
The Halo microchip scanner can read temperature sensing microchips. Plus they come in a range of colours! I only have white, black, pink and purple so far…

How to stop your dog getting heatstroke – according to science

Published by The Conversation on-line, 21.06.2017 Available here.

Summer is a great time to get out and about with your dog. But dogs don’t tolerate the heat as well as their owners. When people get hot they start to sweat, but dogs are only able to do this through the pads on their paws. Dogs instead rely on panting as their main method of cooling.

But panting can only control body temperature up to a point. As temperatures and humidity rise, panting is no longer able to cool the dog. This leads to an increased risk of heatstroke in dogs, which is potentially fatal. It’s worth remembering that it can take around two months for a dog to acclimatise to high temperatures so it is important not to become complacent.

What is heatstroke?

Like humans, dogs can develop heatstroke in two main ways. Environmental heatstroke occurs following exposure to high temperatures, the classic example being a dog left in a hot car. Exertional, or exercise-related, heatstroke occurs during or following exercise and can happen at any time of the year. Heatstroke happens when an animal is no longer able to cool itself and its body temperature can no longer be controlled. When the dog’s body temperature exceeds 40℃, irreversible changes start to happen such as brain damage and multiple organ failure.

Every year, there are numerous reports of dogs dying in hot cars. Cars can get hot surprisingly quickly with internal temperatures reaching 40℃ within just ten minutes of being parked in full sun. Simply exercising or playing in warmer weather can also lead to heatstroke in surprisingly short periods of time, just a ten minute walk could be too much. Dogs that are working or competing in hot conditions are also at risk, so making sure they are kept cool is key.

Certain factors put some dogs at a higher risk of heatstroke. Brachycephalic (short faced) breeds, such as pugs and boxers, are more likely to suffer, as are animals with respiratory disorders. Male dogs and those with darker coats also tend to get hotter in warm weather.

Reducing the risk

Access to cool water is key. Shutterstock

Don’t leave your dog in the car and never leave dogs unattended. Even in the shade, car temperatures can increase quickly and as the sun moves and shade disappears the internal car temperature will rapidly increase. Leaving windows partially open has little effect on car temperature. If you are stuck in traffic or travelling, have the air conditioning on to keep the car cool and make sure windows are shaded from direct sunlight. Ideally, leave your dog at home in hot weather.

Try to exercise your dog in the cooler parts of the day. Avoid any strenuous exercise in the heat. And make sure you supervise activity – your dog may not know when to stop. Instead of exercising in full sun, try brain games in the house or walking in the shade, such as woodland.

All dogs need access to cool water and shade to keep their temperature down. If your dog is unfit, obese or suffers from a respiratory disorder be particularly careful exercising in hot or humid conditions.

As the weather becomes more unpredictable, the risks of being unprepared increase. Even in winter, dogs can be at risk with temperatures getting warmer than expected. The continuing changeable weather also makes it challenging to acclimatise to the heat, making sudden, unseasonal hot spells even more dangerous.

Signs of heatstroke

Heatstroke can happen very quickly, starting with rapid breathing, lack of energy and decreased urine production. This can very quickly escalate to heavy panting, bulging eyes, and the tongue appearing excessively long and dark red. Collapse (leading to seizures or coma) and vomiting and/or diarrhoea can follow.

Both cooling your dog, and getting to the vet as quickly as possible are the two key ways to increase the chance of survival in heatstroke cases. Avoid using ice or very cold water as this can cause blood vessels on the skin surface to constrict and reduce effective cooling. It can also cause shivering which can create more heat from the muscles. Key areas to cool are the neck, abdomen and inner thighs with lukewarm water or water-soaked towels. It is important that you do not over cool your dog, as this can lead to shock – a lack of blood supply to vital organs – so using lukewarm water is important.

Out and about, cool surfaces, shade, air conditioning in cars and fans can also aid cooling. Even if the dog is cooled, veterinary treatment is still key to allow more targeted treatment and monitoring to occur. Heatstroke has been reported as fatal in 39-50% of dogs but those surviving more than 24 hours have a good chance of making a full recovery.

 

The Journey So Far

Thanks for joining us!

We have started this blog to share our research findings with the wider dog owning, dog working, and dog competing community.  Apologies for the lack of content at the moment, but we hope this will soon change!

For now, here are some of our recent research findings and publications in an openly accessible format, along with links to the published works (which are sadly mostly behind paywalls):

FINAL Heatstroke – providing evidence based advice to dog owners.

Link to published version

FINAL Establishing a reference range for normal canine TMT

Link to published version

FINAL Factors affecting canine temperature after canicross racing

Link to the published version

Our current study exploring activity levels in dogs is still open, click here to take part!

Our Conversation UK articles:

How to stop your dog getting heatstroke – according to science

If your New Year’s resolution is to get fit, your dog may be your perfect training partner

Dogs don’t just die in hot cars – here’s how to stop them overheating when exercising

If you have any concerns about your dog’s health please consult your veterinary surgeon immediately.  This site is designed to provide information and share knowledge regarding heatstroke, but is no substitute for veterinary care for your dog