When cats are active, their body temperature will rise briefly, sometimes it may be higher than 39 degrees. Usually let the cat be quiet for a while, and then measure the skin temperature, and the body temperature will drop below 39 degrees, which is normal. For some particularly obese cats, there is a lot of fat under the skin, which will also isolate the temperature, resulting in a low skin temperature measurement or even lower than 37 degrees. In this case, you can choose to put the mercury thermometer on the inside of the front leg and thigh root, and then see if the temperature is normal.