Taking Your Pet's Temperature

By Malcolm Weir, DVM, MSc, MPH; Lynn Buzhardt, DVM

What is a normal temperature in dogs and cats?

Normal human body temperature is 98.6°F (37°C). Normal body temperature for dogs and cats is 101.0 to 102.5°F (38.3 to 39.2°C). Some people and some pets maintain a baseline temperature a little above or below the average, but if your pet’s temperature rises above 104°F (40.0°C) or falls below 99°F (37.2°C), take your pet to your veterinarian.

What is an abnormal temperature?

Unfortunately, there is no easy checklist of signs that indicate high (hyperthermic) or low (hypothermic) body temperatures, but here are some general signs to look for:

  • Hypothermic pets may be lethargic and less alert. They may shiver or tremble.
  • Hyperthermic pets may also be lethargic. They often pant to get rid of excess body heat, and their gums may become dark red.

Since these signs can occur with many medical problems, it is not possible for you to determine if your pet is hypo/hyperthermic just by looking at him. You have to actually take his temperature.

What types of thermometers can I use to measure my pet's temperature?

The only sure-fire way to determine if your pet has an abnormally high or low body temperature is to take his temperature with a thermometer. There are two popular types of thermometers: digital and rectal. Digital thermometers are placed into the ear canal and rectal thermometers are inserted, as the name implies, into the rectum. However, dogs and cats often resist both options so taking a temperature can be challenging.

Old fashioned rectal thermometers contain mercury inside a glass cylinder. The mercury is shaken down into the thermometer bulb, expands when heated, and rises up the calibrated cylinder to indicate the temperature. Reading the thermometer can be tricky but rolling it back and forth horizontally helps display the silver column of mercury. Glass thermometers are easy to break which requires a careful clean up since exposure to mercury is hazardous.

Digital thermometers have an easy-to-read numerical display in either Fahrenheit or Celsius. They calibrate themselves after being turned on. Digital, aural thermometers are inserted into the ear canal and need to be close to the ear drum to get an accurate reading. Due to the many sizes and shapes of dogs’ and cats’ ear canals, digital temperatures are not always precise. Plus, the presence of hair, wax, and debris in the ear canal can affect accuracy.

How can I take my pet's temperature?

Regardless of which thermometer you use, taking your pet’s temperature may be a two-person task. One person can hug your pet to provide comfort and restraint simultaneously. Cats and small dogs can be held in the lap with one arm placed under the neck holding the head snug against your body. The other arm can be placed around the abdomen to keep the pet still. Large dogs can be held in a similar manner on the floor.

"Regardless of which thermometer you use, taking your pet's temperature
may be a two-person task."

When using a digital aural thermometer, your pet may stand up. When a rectal thermometer is inserted, a standing pet will likely sit down on the thermometer. It is best to lie the pet down on its side before inserting a rectal thermometer.

Rectal Technique: Shake down the thermometer. Lubricate the tip with petroleum jelly to ease insertion. For small dogs and cats, the thermometer should be advanced slowly about an inch. For larger dogs, insert the thermometer about 2-3 inches into the rectum. Hang on to the end of the thermometer to steady it and make retraction easier. If you feel stool in the rectum, try to place thermometer around it rather than through fecal matter as this may give a falsely low temperature reading.

If using a glass thermometer, leave the thermometer in place two minutes (if using an electronic thermometer, the device will usually beep when the temperature is ready to be read). Remove the thermometer and wipe it clean with a tissue prior to reading. If the pet clamps down his anal sphincter, do not force the thermometer into the rectum to avoid injury and pain for the pet.

Digital Aural Technique: Turn the thermometer on and allow it to calibrate. Many digital thermometers will beep when calibrated and beep again when ready to read. No lubrication is needed prior to inserting the thermometer into the ear canal. Insert the thermometer gently into the horizontal ear canal by holding it at a 90°angle with the pet’s head. If your pet resists, do not force the device into the ear canal. An infected ear is sore and inserting a thermometer will be painful. Additionally, using an ear thermometer on a dog or cat with an ear infection will produce inaccurate readings.

If taking your pet’s temperature is difficult, do not risk injury to him or to yourself. Allow trained professionals to accurately and safely take his temperature at your veterinary hospital.

What should I do if my pet's temperature is higher or lower than normal?

First of all, double check all abnormal (high or low) temperature readings. Falsely elevated temperatures occur when pets are over excited or agitated. Dogs and cats that resist restraint may have high temperatures that do not really qualify as a “fever”. Let the pet rest for 10 minutes, calm him down, and try again. If your pet’s temperature is too low, the thermometer may have been inserted inappropriately. An abnormally low temperature may result when the thermometer is not inserted far enough in the ear or when it is embedded in feces in the rectum.

"If your pet's temperature remains high or low, see your veterinarian."

After rechecking, if your pet’s temperature is still moderately elevated (102.5-103.5°F), give him a small amount of water or ice chips. Apply cool damp cloths to his paws and place him in a ventilated area. If his temperature is too low, wrap him in warm towels or blankets. Hot water bottles may help but avoid heating pads which can cause burns. If your pet’s temperature remains high or low, see your veterinarian. Remember that temperatures above 104°F (40°C) or below 99°F (37.2°C) are emergency situations.

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