How to measure fever in dogs and cats?

In adult dogs and cats, the normal body temperature is about 38-38.2°C. While in puppies it is about 38.5-38.8°C.

The temperature should preferably be measured in the morning or evening, away from meals and not immediately after a run or a walk. In the morning it is usually lower than in the evening. The thermometric survey is carried out rectally using prismatic thermometers for children.
Before using the thermometer it is advisable to lubricate it with Vaseline or olive oil. The tail must be lifted, and the thermometer inserted into the anal opening, taking care to keep it slightly oblique so that the bulb is in contact with the wall of the rectum. Keep it in place for about a minute, remove it and read the temperature.