Taking a dog's temperature can be an important way to assess their health. Typically, using a digital rectal thermometer is most accurate. You should lubricate the thermometer and insert it gently into the dog's rectum, about one inch. A normal reading is around 101-102.5°F (38.3-39.2°C). Do you have any concerns about your dog's health right now, or are you gathering information just in case? I'm here to help with any questions!