It's operated by then pressing a button to turn it on. Simply lubricate with petroleum jelly and insert the thermometer into the horse's rectum. It may take one to three minutes for an accurate reading, although many digital thermometers take readings quickly and beep when they are done. Simply read the digital display for the horse's temperature. Understanding the information Normal body temperature runs 99.8-101.3 F, but environmental factors can affect the readings.
Horses tend to have higher temperatures in warm weather.
Exercise, stress or excitement will raise temperature as well. This is why it's important to take your horse's temperature many times and in many different situations so you will know what the norm is. Temperatures over 102 are usually related to some type of disease. Bacterial infections, such as respiratory colds and infected cuts usually generate temperatures in the 102.5-103.5 range. Occasionally, infections will cause biphasic fevers that show a normal temperature in the morning, but will spike a high temperature in the afternoon.