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

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…

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