Winter has already been harsh this year. Hypothermia has many causes and can affect lambs at different ages. In newborn lambs less than five hours old, hypothermia often occurs due to prolonged exposure to cold temperatures.
Difficult or premature births can cause weak, hypothermic lambs they do not get up and nurse warm colostrum as readily as lambs that have a normal birth. Poor mothering can also lead to hypothermia if an ewe fails to thoroughly lick her lambs dry or if she abandons a lamb.
If the ewe has poor body condition and/or there was a lack of adequate nutrition during gestation, the risk for hypothermia increases as lambs born from these ewes are often weak and colostrum production is decreased. Poor nutrition will result in a small, weak lamb at birth with little internal body fat. The hypothermic risk is higher in triplet or quad lambs.
Hypoglycemia (low blood sugar) often accompanies hypothermia in newborn lambs. To maintain body heat after birth, the lamb must use its' own brown fat energy reserves to generate heat. With oxygen these fat reserves are converted to energy plus heat. The trigger to start this process is a component of the ewe's colostrum.
Simply put, lambs that have not nursed colostrum within five hours after birth are at a higher risk for hypoglycemia and will need glucose supplementation before warming. They simply have not ingested colostrum which is both a source of immunity and glucose.
Lambs that have not received enough good quality colostrum in a timely manner are also at risk of sepsis associated hypothermia. This is a secondary issue to lack of maternal immunity. Septic lambs will not respond to basic hypothermia and hypoglycemia treatment. They should be seen by a veterinarian as soon as possible.
Symptoms of Hypothermia
Diagnosis of hypothermia in any age lamb is straightforward. Normal lamb body temperature is 102 degrees; a reading below 99 degrees indicates severe hypothermia. Always have a clean, functioning thermometer on hand to take the body temperature of a lamb at the first suspicion of hypothermia.
A subnormal body temperature of 100°F (38'C) or less.
A hunched posture
Lethargic and weak
Hollowed-out sides
Excessive bleating
Dehydration
Lack a suckle response
Unable to hold up their head
Mild to Moderate Hypothermia
Treatment of hypothermia varies based on the severity and the age of the lamb. A lamb with mild hypothermia with a body temperature of 37-39C (99-102F) is mildly hypothermic should first be thoroughly dried off before receiving colostrum via a stomach tube.
Personally, I dry them off as much as possible and wrap them in a towel as I'm waiting for commercial colostrum to warm up. They don't have to be absolutely dry before you tube them.
You can also warm and wrap the lamb, then milk the ewe for her colostrum and then tube the lamb with 50-100ml warm colostrum every two hours. Just make sure you warm the tubing prior to insertion.
It is a better option to tube hypothermic lambs since they often lack a suckle response. Giving colostrum via bottle without a suckle reflex may result in aspiration pneumonia and subsequent death of the lamb. Contact your veterinarian or experienced shepherd to learn how to tube a lamb.
If warm, fresh colostrum cannot be obtained from the ewe, use a commercially available colostrum replacer. Do not use a colostrum supplement because it does not have a high enough concentration of antibodies as a replacer.
Often these colostrum replacers are made for calves but will work well for lambs also. Mixing instructions will be the same for calves and lambs but obviously a lamb does not need as much volume as a calf. A lamb should receive 10% of its body weight in colostrum over at least a few meals during the first six hours of life.
Another option is to keep fresh-frozen colostrum on hand. Fresh-frozen bovine colostrum can be used but try to make sure it comes from a healthy herd since Johnes disease transmission through the milk to lambs is possible. Some producers will choose not to use cow colostrum or ewe colostrum from other flocks due to this risk, so consider retaining fresh-frozen colostrum from your own ewes.
Warming can be accomplished by many methods. The lamb needs to be warmed slowly to restore their body temperature. A warming box is best, but there are many options. For example:
Use commercially available warming boxes
Use blankets or towels warmed in a dryer prior to use
Place warm jugs of water or heating pads under the lamb
Put the lamb in a garbage bag (with their head sticking out so they can breath) and immerse in a bucket of tap hot water.
Personally, I use a small water tank with shavings that sits in hubby's shop all winter to stay warm and then use a red Infared heat lamp (similar to what is used for keeping chicks warm) to warm up the lamb. My Border Collie, Wendy, also likes to jump in the warming tub and snuggles the lambs to warm them. I also use small dog jackets from the Dollarama on the lambs for the first 2 weeks of life to help keep them warm for frosty nights and windy days.
Check the lamb's rectal temperature every 20-30 minutes to avoid overheating above the normal rectal temperature (hyperthermia). Once the lamb's rectal temperature has reached 37°C, remove it from the warmer, given a feed of colostrum by stomach tube, then returned to the ewe. If it is still weak, placed in an "aftercare" unit. Do not return the lamb to the ewe unless it is strong enough to nurse unaided. The aftercare unit can be the same warming box you used with the heat lamp on low.
Moderate to Severe Hypothermia
Severely hypothermic lambs with a body temperature of less than 37C (≤99°F) require more aggressive treatment. A lamb that is less than five hours old and severely hypothermic needs to be dried and warmed before giving colostrum via stomach tube.
Lambs that are severely hypothermic and greater than five hours old must receive colostrum first before drying and warming. Lambs more than five hours old do not have any brown fat reserves left. If these lambs are warmed before receiving glucose in the colostrum, they will convulse and likely die. Again, a stomach tube should be used to give colostrum.
However, if the lamb cannot hold its head up, tubing can be a challenge and there is an increased risk for aspiration pneumonia since it is more likely for the tube to enter the trachea and lungs instead of the esophagus and stomach.
In this case, Karo corn syrup can be rubbed on the gums of the lamb because absorption of sugar across the gums occurs rapidly. Alternatively, an intraperitoneal glucose injection can be given if you are comfortable doing this.
Inexperienced shepherds should not attempt intraperitoneal injections without instruction from a veterinarian since there can be severe complications with incorrectly injecting any solution into the abdomen of any animal. After these lambs have been given some energy, begin the drying and warming process. It is recommended to tube these lambs again after their body temperature has increased.
Overall, it is important to remember that the best treatment for hypothermia in lambs is prevention, such as:
Ensure that lambs are born in a clean, dry, well-bedded lambing area
Keep track of when your ewes were bred so that you know when they are expected to lamb. Then you can predict when to move ewes into their lambing area.
Try to make your lambing area as draft free as possible
Make sure your heating lamps are secured well to reduce the risk of fire
Watch the weather. If you know a cold snap or blustery winter conditions are coming, get ready before hand. It's easier to put out more feed and setup lambing jugs in the barn rather than fighting frozen equipment in frigid winds and defrosting lambs found frozen in the snowbanks.