The body temperature of cows is a precise health indicator. Changes in body temperature are often the first sign of an acute illness. A change in body temperature already occurs before clinical symptoms are visible.
In this article you will learn more about changes in body temperature in dairy cows and why continuous measurement provides so many benefits. In addition, we show you example curves from the smaXtec Messenger that show temperature increases or decreases. The smaXtec system makes you aware of changes in temperature at an early stage. This enables you to initiate relevant measures immediately.
Regular body temperature in dairy cows
A precise determination of the normal temperature of cattle does not exist. Sources suggest, however, that the following values occur frequently and therefore function as guidelines:
• Calves: 38.5 to 39.5 °C
• Heifers: 38.0 to 39.5 °C
• Adult animals: 38.3 to 38.8 °C
When a body temperature higher than the above-stated normal values occurs, we usually speak of a feverish condition.
Of course, body temperature can also fall below the standard values. Where this is the case, the animal is suffering from hypothermia (below 37.5 °C). 
Depending on the lactation phase, the inner body temperature in the rumen is 0.5 to 1 degree higher than with a rectal measurement. However, it correlates with the temperature measured at other parts and can therefore be used for continuous health monitoring.
Increased body temperature
An animal suffers from fever when the body’s core temperature is increased. Here, the body sets in motion a process by which it can better combat harmful invaders such as viruses, bacteria and parasites. Stress and acute shortages also express themselves quickly through changes in body temperature.
Fever is a natural defense mechanism of the body and should not always be seen as being negative. For example, an increased body temperature helps to accelerate certain processes in the organism.  However, farmers must pay attention to ensure that measures are taken quickly to support the animal, or that the animal subsequently receives any necessary treatment.
Increased body temperature may indicate:
• Infection (bacteria, viruses etc.)
• Inflammation (uterus, udder, lungs etc.)
• Stress situation (heat, birth, transport etc.) 
If the animal is suffering from a viral infection, the body usually reacts with fever so that the white blood cells can fight the pathogens faster. An increase in body temperature is often the first sign of an infectious disease and can also be caused by toxins that have entered the bloodstream. Also, a locally infected claw joint can cause fever when the pus pathogens break into the bloodstream. 
Decreased body temperature
If the animal has a low body temperature, this shows that processes in the body are not working in a normal way.  For an extended period of time the body tries to prevent the temperature from falling. Muscle tremors enable heat to be produced in order to counteract hypothermia but when the organism can no longer compensate for heat loss, body temperature drops significantly. 
A low body temperature can quickly become life threatening. It requires immediate attention. Cows that suffer from parturient paresis (milk fever) are particularly liable to quickly reach a dangerous stage.  Measures include calcium supplements, infusions, infrared lamps, blankets, moving to another part of the stable or thick/dry litter. 
A low body temperature may indicate:
• Parturient paresis (milk fever)
• Upcoming calving
• Lack of energy supply
• Indigestion 
• Metabolic diseases (e.g. ketosis)
A pathological decrease in body temperature can occur when cattle have been exposed to windy, wet, cold weather during transport or pasture over an extended period of time. Drafts in the stable, high blood loss or incipient comatose conditions, such as severe parturient paresis, may be the cause of abnormally low temperature.  The body temperature also drops shortly before an upcoming calving.
Continuous temperature measurement instead of intermittent measurement
Data collected via temperature taking is only meaningful over the course of time. It is therefore important that temperature is measured continuously and also that the course is also documented. This is the only means by which signs of illness can be recognized and interpreted correctly at an early stage.
Temperature measurement is a great early warning system and should be carried out routinely on every farm. On larger farms, however, the time required for monitoring of temperature by hand is enormous. In addition, it is crucial to know and take into account the “history” of the animal in case of temperature changes. A precise record is therefore very helpful.
Especially in critical phases, it is important to measure the body temperature of dairy cows. However, it may easily happen that you do not notice short fever episodes when you take the cow’s temperature two to three times a day. It is only through continuous observation that even short temperature changes can be detected and attention given to the animals that need it.
Detect feverish conditions in all stages of lactation
Taking the temperature of freshly lactating cows is standard on most farms, but the continuous monitoring of the body temperature can detect disease in animals in other phases of lactation as well.
For example, smaXtec customers report that the system detected pneumonia in dry cows that are normally not under observation. This allowed the farmers to treat their animals earlier and thus use less medication. The smaXtec system gives you the security of really having all your animals in sight.
How smaXtec continuously monitors temperature in dairy cows
The smaXtec Bolus in the cow’s forestomach provides a continuous body temperature measurement deep inside the cow’s body. The sensor’s position enables precise and unfalsified measurements to be taken in real time. Using the smaXtec system means farmers no longer have to take temperature manually. This saves time and allows the temperature of each animal to be tracked over time, making it possible to quickly react to the onset of illnesses or find the reasons for the change in temperature. Additionally, measurement of the inner body temperature has another advantage: it provides you with information about the type of illness.
The smaXtec Bolus not only enables diseases and the onset of calving to be detected at an early stage through continuous temperature monitoring, but also offers farmers the opportunity to observe how their animals are recovering.
Here are sample curves from the smaXtec Messenger, which illustrate how versatile the system is. Both increased and decreased temperature are detected immediately by the bolus and measurements can be taken as early as possible.
Increase in temperature: mastitis
Early detection: smaXtec detects a short-term deviation in body temperature approximately 36 hours before clinical signs (such as flakes in the milk) are visible
You can react quickly and can reduce the usage of antibiotics. The risk of a drop in milk production and consequential damage, such as the loss of an udder quarter, can thus be minimized.
Decrease in temperature: parturient paresis (milk fever)
Typical signs of the disease such as lack of movement and slightly falling body temperatures can be detected by the smaXtec system at an early stage. As the disease progresses, the cow lies down and is unable to rise.
smaXtec detects reduced activity and the temperature drop typical for metabolic diseases. This enables you to react quickly and at an early stage. Rapid intervention can prevent subsequent illnesses.
The birth process is typically initiated by a drop in body temperature a few hours before calving. This characteristic decrease in body temperature is detected by the smaXtec system and a calving alarm is generated.
You receive an early warning before the calving enabling you to take any necessary steps (such as preparing the calving box). Animals that are at increased risk of parturient paresis may be provided with sufficient calcium in advance of calving. The system also enables close monitoring of the calving process.
You want to work with the system on your farm to continuously monitor body temperature and thus detect diseases earliest possible? Contact us!
 Weiß et al. 2005: Tierproduktion