Unfortunately, your beloved canine companion cannot tell you in words when he or she is feeling ill. Instead, your dog can give you hints that it is not feeling well through changes in its behavior, including being less active or not as interested in food. However, finding out if your dog has a fever is a good way to figure out if it is actually sick. Documenting changes in body temperature could help a veterinarian to identify the cause of the illness in your dog and therefore help with treatment options. As part of your “doggy” first aid kit, you should have a dedicated doggy thermometer that you can use to find out if your dog has a fever.