The average body temperature of dogs is between 38 and 39 degrees. Small dogs should be higher, ie close to 39 degrees, and large dogs should be close to 38 degrees. If we want to make sure our dog has a fever, we need to feel the abdomen where there is less hair or take a fever at the anus with a thermometer. Dogs otherwise behave similarly to humans in the presence of fever, meaning they will be depressed and, of course, due to their malaise, will mostly just lie down and stare sadly, possibly sleep. Higher fever can cause tremors, as they can catch a cold.