Taking your dog’s temperature will help you determine when she is sick and will allow you to provide accurate information to your veterinarian. The skin temperature — the warmth or coolness of a dog’s skin, ears, or nose—is misleading.
The true body temperature should be determined using a rectal thermometer. The same thermometers designed for oral use in humans are appropriate for rectal use in animals. These include glass mercury thermometers and plastic battery-operated thermometers with digital displays. You can also use thermometers designed for rectal use in human babies.
Glass thermometers are inexpensive but easily broken, and the glass and the liquid mercury (which is poisonous) are hazardous. Digital thermometers work well with dogs because they do not break easily, the tip is smaller than a glass thermometer, and many of them beep when they reach a final temperature. However, digital thermometers may not be as accurate as glass if your dog’s body temperature is very high or very low.
Before inserting the thermometer into your dog’s rectum, be sure the thermometer is clean, and lubricate it with petroleum jelly or a bit of liquid soap. If using a glass thermometer, shake it down until the mercury reads less than 90°F or 32.2°C. Lift the dog’s tail slightly with one hand and insert the tip of the thermometer with it gentle rolling motion until the tip is about one inch into the dog’s rectum. Hold on to the thermometer at all times.
Although most dogs do not mind this procedure (especially if you distract them with kind words), some will object. A second person may be needed to provide gentle restraint. Some dogs become so agitated that an elevated body temperature is inevitable. In this case, decide whether determining your dog’s body temperature is useful enough to warrant the stress created by taking it. Take your dog’s temperature on a regular basis, beginning when you first adopt her, so that she becomes comfortable with the procedure and you learn what temperature is normal for her. The normal body temperature range for dogs is 99.5-102.5°F (37.5-39.2°C).