How long should a thermometer be left in the rectum to obtain an accurate temperature reading?

Inserting a thermometer into the rectum for one minute is a standard practice to ensure that an accurate temperature reading is obtained. This duration allows the thermometer's sensor enough time to equilibrate with the body’s internal temperature, which can fluctuate rapidly and may not be fully reflected in a reading taken too quickly. While some thermometers may give a reading quicker, particularly digital models, one minute is generally accepted as sufficient for consistent and reliable results.

Touching on the other timeframes, shorter durations, such as 30 seconds, may not provide adequate time for the thermometer, especially if it's a glass or older model, to stabilize and gauge the accurate temperature. Conversely, extending the measurement to two minutes or five minutes tends to be unnecessary for obtaining precise readings and can subject the animal to discomfort or stress without providing additional benefit. Thus, one minute strikes an optimal balance between accuracy and the welfare of the animal.