Michelle Arnold, DVM
(UKVDL) Ruminant Extension Veterinarian
When the weather is predicted to be bitterly cold, producers
should take extra care of newborn calves to ensure their survival. A
calf’s body temperature often falls below normal in extremely cold conditions
due to a slow or difficult birth (dystocia) followed by delayed standing and
nursing. Returning the calf’s core body temperature to normal (100°
F for newborn calves) then maintaining that core temperature is of primary
importance. If at all possible, bring close-up cows indoors to calve in a
heavily bedded, clean pen. If calving outdoors, make sure there is dry,
clean ground available for the cows to calve without a large amount of manure.
If the cow calves outdoors, bring the calf in until warm and dry if the calf is
showing signs of hypothermia or if there are no natural windbreaks available.
There are two types of hypothermia: exposure (gradual) and
immersion (acute). Exposure hypothermia is the steady loss of body heat
in a cold environment through breathing, evaporation and lack of adequate hair
coat, body flesh or weather protection. This type of hypothermia affects all
classes of livestock but particularly affects young, old and thin animals.
Immersion hypothermia is the rapid loss of body heat due to
a wet, saturated hair coat in a cold environment. Immersion hypothermia
often occurs after the birthing process because the calf is born soaked with
uterine fluids. Other causes of immersion hypothermia of young calves may
include being born in deep snow or on wet ground, falling into a creek or being
saturated from heavy rains followed by chilling winds.
Signs of Hypothermia
Faced with a cold environment, the body defends itself in
two ways: shivering, to increase muscle heat production, and blood shunting, to
reduce heat loss by diverting blood flow away from the body extremities to the
body core. Mild hypothermia occurs as the body's core temperature drops below
normal (approximately 100° F. for beef calves). In the early stages, vigorous
shivering is usually accompanied by increased pulse and breathing rates. In the
case of newborn calves, severe shivering may interfere with its ability to
stand and suckle. Erratic behavior, confusion and a clumsy gait, are all
signs of mild hypothermia. Producers often refer to these as "dummy"
calves. Severe hypothermia results as the body temperature drops below
94° F. Cold nostrils and pale, cold hooves are early signs that blood is being
shunted away from the body's extremities. Paleness is due to poor
oxygenation of the tissues near the body surface. Decreased blood circulation
in the muscles of extremities results in a buildup of acid metabolites (waste
products). After the shivering stops, it is replaced by muscle rigidity. The
pulse and respiration rates begin to slow as the body core cools to 88° F.
Below a core temperature of 94° F, the vital organs are beginning to get cold.
As the brain cools, brain cell metabolism slows, resulting in impaired brain
function. The level of consciousness deteriorates to eventual unconsciousness.
Below 86° F., signs of life are very difficult to detect and the calf may be
mistaken for dead. The pupils of the eyes will be dilated and fixed. The pulse
may be undetectable. Occasional gasps of respiration at a rate as low as four
or five per minute may be the only clue that the calf is still alive. Heart
failure is often the actual cause of death.
Treatment of Hypothermia
The two most important factors in calf survival are warmth
and colostrum. Before giving colostrum, a chilled calf first needs to be
warmed as these newborns are typically too weak to suckle. Karo syrup
(dark is preferred) delivered by mouth to a weak calf is a quick source of
readily available energy and is rapidly absorbed through the mucosa in the
mouth into the bloodstream. Effective methods to warm a calf include:
1.
Floor board heaters of pickup trucks.
2.
Submersion of wet calves in a warm bath-you must support the calf to
prevent drowning. The water should be gradually warmed to 100° F and will
need to be changed to keep it at that temperature.
3.
Placing calves next to the heater in the house and/or using a blow dryer
to dry and warm the hair coat. Never leave calves unattended next to a
portable space heater.
4.
Placing the calf under a heat lamp-be careful to cover the lamp with a
screen so the calf will not get burned as it becomes more active. Do not
leave the calf unattended.
5.
Warm blankets-These should not be so hot that they can cause skin
burns. Change the blankets as needed to maintain a consistent temperature
and not allow the calf to cool off.
6.
Hot box or warming box-the temperature should not be so high that burns
could result. Some type of venting is necessary to prevent buildup of
carbon monoxide and moisture. Air movement is also important to ensure
thorough warming of the calf and prevent hot spots in a warming box.
7.
Warm IV fluids may be administered by a veterinarian.
Once the calf has been warmed, provide colostrum and
maintain body temperature. Colostrum is a concentrated source of protein,
vitamins, minerals and energy and also contains life-saving antibodies to
disease. If the calf is unwilling to suck, use of an esophageal feeder is
recommended to deliver colostrum. If it is not possible to milk the dam,
commercial powdered colostrum replacement products are available. Calves
should be fed colostrum as soon as possible after the suckle reflex has
returned-generally within the first 6 hours after birth but ideally within 1-2
hours after birth. Once the calf is warm and fed, move it back to its
mother. It is important that they have a place to get out of the wind; a
draft free place to go during extreme wind chill days/nights.
Other Tips on Dealing with Livestock in Extreme Cold
Water is critical. Livestock need water to maintain
their health and immune system. Lactating animals have a higher need for
water than young stock and mammals in their dry period. Livestock will
reduce their consumption of feed and produce less milk if they don't have water
available. Check your water source several times a day. It's
vital for the health and production of your animals. In addition,
consumption of salt without water available can result in salt poisoning which
often results in death of the animal.
Cold temperatures
will increase maintenance energy needs. Producers either need to increase their
animals’ feed intake or increase the energy density of the diet by feeding
higher quality hay or adding grain to the ration. Consider separating
younger and thinner animals that may not have the same internal insulation as
conditioned older animals and supplement them accordingly or offer them higher
quality forage if available.
Take care of yourself too. Keep an extra set of
clothes and a blanket in your truck. If you get wet while doing
chores, being able to change into dry clothes quickly could be the
difference between finishing chores with just a nuisance - or getting
hypothermia. An extra pair of dry boots is a great plan too.
Let someone know when you are going out and always take a cell phone in the
event of an emergency. If you get into trouble, then you can't be the caregiver
of your livestock that you want to be.
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