This winter’s frigid conditions have put young calves under considerable stress. Helping calves cope with cold stress, or hypothermia, may be critical to their survival. Three important principles for recognizing and treating the condition include:
- Hypothermic conditions in calves vary from mild to severe.
- Take temperatures to confirm suspected cases of hypothermia.
- Treat hypothermic cases promptly to minimize subsequent health problems.
Mild cold stress or hypothermia
At this stage of cold stress we observe vigorous shivering. If we look carefully we will see pulse and breathing rates above normal. Recall that the normal pulse rate of a calf at rest falls in the range of 70 to 100 beats per minute; normal breathing rate of a calf at rest falls in the range of 20 to 40 breaths per minute.
These calves are likely to have a body temperature around 100°F rather than the more normal 102°F.
Check for an excessively cold nose. Cold hooves, too, are a clue that blood is being diverted away from extremities.
At this stage of cold stress shivering may slow or even stop. Shivering is replaced by rigidity – muscles are stiff. Nostrils will be cold and pale. Calves, if standing, may be clumsy and act confused. They are unlikely to suckle.
Pulse and breathing rates continue to slow. Body temperature continues to fall below 100°F. Textbooks tell us that at the mid-90°F level the vital organs are chilling. Even the brain is beginning to get cold.
Diagnosing cold stress or hypothermia
Due to hormones that accompany birth, calves experience a surge of energy and are able to stand 30 to 60 minutes after delivery. After a hard birth many calves look okay until these hormone levels drop.
They look and act normal. Then, after 15 or 30 minutes they may get progressively weaker, have a weak suckle response and be unable to stand. Often their body temperature has begun to slide down to 100°F or less. Definite diagnosis? Take the calf’s temperature.
Preweaned calves are more likely to experience hypothermia where there is sustained loss of body heat. If outdoor-housed calves that get wet, lie on cold bedding or experience windy conditions, they can lose more heat than they can generate. In naturally-ventilated calf barns, winter temperatures combined with drafts and poor bedding may cause gradual hypothermia. Definite diagnosis? Take the calf’s temperature.
Treating mild hypothermia
Warm up the calf. For newborn calves the first step is to make sure the calf is dry – to stop evaporative heat loss (See www.atticacows.com in Calving Ease, “Drying Off a Calf” March 2010). Rubbing the calf vigorously with clean, dry towels not only gets the calf dry but also stimulates higher pulse and breathing rates. I like to add a clean, dry calf blanket, too.