If your dog seems to be off his game but there’s no apparent cause, it’s a good idea (and a reassuring one) to take his temperature and see if there is a physical problem.
Normal range for small dogs is 100 to 102 F or 38 to 39 C. Anything outside that range requires veterinary care and a temperature of 103 or higher is a medical emergency.
It’s a good idea to take your dog’s temperature when you know he’s well or at a routine vet visit so you see what’s typical for your dog.
If you use a non-rectal thermometer, always take his temperature in the same area of his body. For example, always use his ear, his gums or his groin rather than using a different body area each time.
Make sure your dog is in a comfortable position away from any cold or heat source that might distort his body temperature.
Nothing, however, beats a rectal thermometer for accuracy. Use a little Vaseline to help with the insertion.
Here’s a short clear video on how to use a digital rectal thermometer to take your dog’s temperature.