6 Signs of Calf Wellness- Understanding Body Temperature

6 Signs of Calf Wellness- Understanding Body Temperature

Body temperature is just one piece of the puzzle when identifying illness in calves. Just like other warm-blooded mammals, a calf’s core temperature does not depend on the environment. Normal body temperature range for a bovine calf is 100°F - 102°F (37.7°C - 39°C). Most of the time this body temperature will stay relatively consistent. Calves maintain their body temperature by converting the food they eat into body heat.

Small changes in body heat occur every day. During sleep body temperature tends to decrease. During strenuous activity it will likely increase. High summer-time temperatures will also cause a slight increase in body temperature. One exception to normal body temperature fluctuation is an increase in temperature due to illness, called a fever.


Once a pathogen has multiplied and established itself, then one of the common body responses is a fever. If the calf is experiencing a fever they may also be depressed, go off-feed, and have an elevated pulse rate. The calf’s body becomes hot and dry, respiration rate increases, and the calf may become severely depressed, and unable to stand. Accurate diagnosis of calfhood illness depends heavily on knowing body temperature. Please work with your veterinarian to establish a treatment protocol for calves experiencing a fever.


Daily health checks should be completed for each young calf. Calves exhibiting any signs of illness such as; not eating, depression, lethargy, nasal discharge, ocular discharge, or scours qualify for closer examination, including monitoring of body temperature.

  1. Quietly restrain the calf.
  2. Grasp the end of the thermometer with your thumb and first two fingers, with bulb end pointing towards the calf.
  3. Mercury thermometers: tie a string to the thermometer to make it easy to retrieve. Before inserting the thermometer, hold it away from your body and snap it downward to settle the mercury.
  4. Digital thermometers: some are made specially for calves, but even human thermometers often work well. These are often simple to use and they will notify you when the temperature reading is stable.
  5. Lubricate the bulb end of the thermometer.
  6. Gently pat the calf, and place one hand on the calf’s hip to steady it and prevent it from moving. With the other hand, gently place the bulb end of the thermometer on the calf’s anus.
  7. Gently turn the thermometer, adding slight pressure, as you push the thermometer through the anus and into the rectum.
  8. Push the full length of the thermometer into the rectum. Mercury thermometers will stay about 1 inch outside of the calf’s body. The thermometer must be directly touching one side of the rectum for an accurate temperature reading.
  9. Mercury thermometers will need to stay inserted in the rectum for 1-2 minutes for an accurate reading. To read the thermometer remove it slowly and clean with a paper towel. Rotate the thermometer until mercury can be seen next to degree graduations. Look for the top of the mercury column and determine which graduated degree is closest to it.
  10. Digital thermometers will usually beep or otherwise indicate when they have reached a constant reading. Before removing the thermometer, press the button to store the recorded temperature, or just read the temperature. Withdraw the thermometer slowly and wipe clean with a paper towel.
  11. Determine whether the temperature reading is within the normal range. Work with your veterinarian to establish a treatment protocol for calves exhibiting abnormal temperatures.
  12. Don’t forget to keep a record of temperature readings, and any treatments given.
  13. Release the calf.

Reap the Rewards

We know that the calf’s body temperature is just one piece of the puzzle for identifying disease. Other health observations are also important. The ability to accurately pinpoint a problem early before illness sets in and unrepairable damage is done, is essential in providing the opportunity for calves to completely recover from disease. We rarely get second chances with sick calves. One of the most under-diagnosed diseases in calves is pneumonia. A fever and rapid breathing are 2 common symptoms of the onset of pneumonia.  Establish a protocol for early identification and intervention with your veterinarian. Keep a thermometer handy at all times, so it is easy to monitor body temperature and identify sick calves.


Written by: Mariah Gull, M.S.

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