In winter lambing flocks, hypothermia and starvation of newborn lambs can account for nearly all of the pre-weaning death loss of lambs. It’s a serious problem that can often be minimized through management of the ewe flock and its environment.
Even under the best management in the best environment, there will still be some cases of hypothermia and starvation in most winter lambing flocks. With attention to detail, hypothermia and starvation can be reduced to very low rates even in flocks that lamb in the dead of winter in very cold climates. In most sheep production systems, the majority of the cost of producing a lamb is already spent when the lamb is born (in the form of feed and keep), so saving chilled lambs is an important way to protect your investment. Preventing it from happening in the first place is even more important.
When it does happen, it’s important for shepherds to know how to recognize, treat, and, most importantly, learn from each case. In most cases, the problems that lead to hypothermia and starvation are difficult to fix during lambing. They can go back months to the level of nutrition in early gestation, or to barn design, or the availability of bedding. That’s why it’s important to keep records about the causes of any hypothermia cases. Once lambing is over, it’s easy to put those problems out of your mind and forget to fix them for next time. Make a habit of keeping good lambing records and reviewing them well before the next breeding season so that you have time to make any changes or cull any ewes to reduce problems in the next lambing season.
In the meantime, you need to try to save as many cold lambs as possible. Here’s a step-by step guide to the process. The goal of this guide is to help you make sound decisions about how to treat a lamb when you’re tired, busy, and probably a little upset. All the steps are aimed at getting the lamb back with its mother as soon as possible, and are based on the assumption that the mother has adequate milk and has not rejected the lamb. If that is not the case, the lamb will need to be grafted or raised as an orphan, but the initial intervention steps are the same.
Understanding hypothermia and starvation
In newborn lambs, hypothermia and starvation go hand in hand, and left unchecked they fuel one another leading to the death of the lamb. When a lamb is born, it has a reserve of brown fat that releases a tremendous amount of energy during the first few hours of life, keeping its blood sugar high and providing it with enough food to jump start its metabolism.
During these first few hours, the lamb must start to take in the ewe’s colostrum in order to sustain its metabolism and keep itself warm. But digesting food takes energy, and that’s another role that the brown fat plays. If the lamb doesn’t have enough brown fat, or if it doesn’t get colostrum before the brown fat’s energy is all used up, its metabolism can slow down to the point where it can’t digest colostrum. It starts to get cold, and loses more energy. The cycle starts to fuel itself — the lamb lacks energy because it’s chilled, so it doesn’t get the energy it needs to get warm. The shepherd must intervene, or the lamb will die.
Recognizing a chilled lamb
As with most interventions, the earlier the shepherd spots the problem and responds to it, the more likely he is to be successful, and the less time and effort will be required to achieve success. Spotting a lamb that is just starting to have trouble is a key skill. Things to watch for include a hunched posture, hollowed out sides, excessive calling, lethargy, and dehydration. If you pinch a lamb’s skin over the spine, it should snap back almost instantly. If it stays in place like a tent, the lamb is dehydrated and probably needs attention.
In many cases where hypothermia-starvation is in its early stages, all that’s required is to make sure that the lamb gets a good suck from the ewe. The ewe’s teat may be plugged too tightly for the lamb to start the milk flow, or the lamb may have had difficulty finding the teat. If the lamb starts to suckle with assistance, you can often postpone any further intervention and monitor the situation closely to ensure that the lamb and ewe are getting on smoothly.
Any lamb that is unresponsive or laying flat out on its side requires immediate attention.
Perhaps the best way to learn to recognize a chilled lamb is to watch the behavior of lambs that are doing just fine. There’s an indescribable look to a well-fed and happy lamb, and once you know it you will have little trouble spotting the ones that lack it.
Caring for the ewe and other lambs during intervention
If a lamb needs to be removed from its mother, the dam should be left penned by herself where she cannot try to claim other lambs. If a ewe has more than one lamb, consider removing not just the chilled lamb, but all of them. The process of warming a lamb can take several hours, and during that time, a ewe may forget about one of her lambs. She will not forget about all of them. However, you must return the non-chilled lamb or lambs to the dam to suckle regularly – probably every 20 minutes to half hour.
When the chilled lamb has recovered and can be returned to its mother, it will still need to be watched closely for a day or longer. It’s often easiest to pen the ewe in a location that will be convenient for these frequent checks at the beginning of the intervention.
Necessary skills
There are also two techniques discussed here that require some training and skill: feeding by stomach tube and administering glucose by intraperitoneal injection. Done incorrectly, either procedure can kill a lamb. I recommend stomach tube feeding of chilled lambs for several reasons. First, it’s a much surer method of getting the required amount of milk into a lamb than attempting to feed it from a bottle with an artificial nipple. Second, it will take less of the shepherd’s time (which is always in short supply when these things happen), and third it can be accomplished even on a lamb that is totally unwilling to suck. Perhaps most importantly, it doesn’t interfere with the lamb’s understanding that food comes from its mother’s udder. A lamb trained to an artificial nipple will stop seeking its mother’s teat at some point.
Most shepherds who have tried both prefer rigid catheters to flexible ones for stomach feeding. A 60 or 120 cc catheter-tipped syringe is also essential. Remove the plunger and catheter from the syringe. Have the milk on hand and warmed to body temperature. Work the catheter down the lamb’s throat and into the stomach, then attach the syringe and pour the milk in. Allow the milk to flow by gravity — do not force the milk in. If you’re using colostrum and it’s too thick to flow, add just enough warm water to get it flowing. Do not use hot water, or the immunoglobulins in the colostrum will be destroyed.
IP dextrose injection is a bit more complicated. The most straightforward explanation I’ve seen can be found at the Alberta Lamb Producer’s Association website: http://ablamb.ca/documents/factsheets/intradex.pdf, which adapts its procedure from David Henderson’s excellent, but very British, Veterinary Book for Sheep Farmers.
The Alberta site makes reference to a typical 4.5 kg lamb, which is about 10 pounds. Adjust the dosage so that your lamb gets 5 ml per pound of the 2:3 solution of dextrose and freshly boiled water (see chart). In the interest of sanitation and sharp needles, I like to use two brand new needles: one for drawing up the solution, and one for the injection.
Dosage chart for mixing IP dextrose injection for various lamb weights
Lamb weight Total injection 50 percent dextrose freshly boiled water
5 lbs 25 ml 10 ml 15 ml
7 lbs 35 ml 14 ml 21 ml
10 lbs 50 ml 20 ml 30 ml
13 lbs 65 ml 26 ml 39 ml
15 lbs 75 ml 30 ml 45 ml
Necessary equipment
The key to this whole procedure is a warming box. The warming box is a contraption that can be simple or complicated, as long as it provides a constant, gentle heat to the lamb. I have rigged up hair dryers blowing into dog crates. Some pasture lambing operations use insulated coolers with hot water bottles. The main thing is that you don’t want to heat the lamb directly; just keep it in a very warm and dry environment. Heating a lamb too fast can be just as lethal as leaving it cold.
Things not to do
Don’t submerge a lamb in warm water. This common trick may work sometimes, but it will wash the scent off the lamb making it less likely that the ewe will reclaim it, and it will generally heat the lamb too quickly. Don’t warm a lamb with low blood sugar. This can send the lamb into convulsions and kill it. Don’t overheat a lamb. Warming a lamb too quickly or to too high a temperature can also kill it. Don’t feed a cold lamb. A hypothermic lamb can’t digest milk or milk replacer, and the food will cause digestive problems as it sits in the stomach.
Step 1. Evaluate
Determine lamb’s age: is it more or less than five hours old?
Determine lamb’s body temperature – ideally with a thermometer, but with your index finger if no thermometer is immediately at hand. If you’re using your finger, err on the side of caution: if the lamb’s mouth feels anything less than very warm, at least go to the next step of finding the thermometer.
Determine lamb’s general condition: able to stand, suck and swallow? Unable to swallow? Unable to stand?
Rub [MB1] the lamb dry if it’s wet.
Step 2. Act
If the lamb’s temperature is over 99 degrees F., regardless of age:
- Collect milk or colostrum from the mother if possible to use in feeding the lamb.
- Feed by stomach tube.
- Return to warming box until it reaches 101 degrees F.
- Return to mother.
For lambs with temperatures lower than 99 degrees F.
More than five hours old, unable to hold up head or swallow
- Give IP injection of dextrose.
- Move to warming box.
- Collect milk or colostrum from the mother if possible to use in feeding the lamb.
- Check temperature every 20 minutes until it reaches 99 degrees F.
- Feed by stomach tube.
- Return to warming box until it reaches 101 degrees F.
- Return to mother.
More than five hours old, able to hold head up and swallow
- Move to warming box.
- Collect milk or colostrum from the mother if possible to use in feeding the lamb.
- Check temperature every 20 minutes until it reaches 99 degrees F.
- Feed by stomach tube.
- Return to warming box until it reaches 101 degrees F.
- Return to mother.
Less than five hours old, able to hold up head and swallow
- Move to warming box.
- Collect colostrum from the mother if possible to use in feeding the lamb.
- Check temperature every 20 minutes until it reaches 99 degrees F.
- Feed by stomach tube.
- Return to warming box until it reaches 101 degrees F.
- Return to mother.
Step 3. Follow up
If the lamb remains weak, it may need to be kept in draft-free, gently heated environment and fed by stomach tube regularly until it is strong enough to return to its mother. If at all possible, use milk or colostrum from the lamb’s own mother for all feedings, as this will increase the likelihood that the lamb will be accepted when returned to her.
Keep the ewe penned up with her lambs in a lambing jug or other easily monitored area where other ewes won’t interfere with bonding, and the chilled lamb will have as few distractions as possible. Watch the lambs for signs of starvation or dehydration until they’re solid and ready to rejoin the flock.
Step 4. Find the cause
Hypothermia and starvation cause a great deal of death loss and their treatment greatly increases labor requirements at lambing time. Shepherds should set a goal both for economic and animal welfare reasons to reduce hypothermia and starvation as much as possible. Each case should be noted in the lambing records of the dam, and the shepherd should attempt to pin down the cause of each case. After the crush of lambing is over, these records can be reviewed to look for patterns that might suggest management changes or culling of individual ewes.
Well-fed and -conditioned ewes can deliver and keep lambs fed and warm under fairly extreme temperatures, provided they are sheltered from wind, drafts, and moisture. Temperature alone should not cause hypothermia-starvation in shed lambed ewes unless the air temperature is below 0 degrees F.
Some management-related causes of hypothermia-starvation in shed-lambed ewes would include:
- Poor maternal nutrition in early gestation when placental development takes place, leading to low birth weights and low milk production.
- Poor maternal nutrition in late gestation, reducing fetal development and resulting in low birth weight and weakness in newborn lambs.
- Inadequate bedding; ewes lambing on wet or frozen pen floors.
- Drafts at floor level.
- Overcrowding of ewes leading to mismothering, grannying, or lost and wandering lambs.
- Inadequate pen construction allowing lambs to wander away from their mothers.
- Some disease-related causes of hypothermia-starvation would include:
- Ovine progressive pneumonia, which can cause reduced (or absent) colostrum.
- Any of the several abortion diseases, leading to weak newborn lambs.
- Mastitis, causing the ewe to refuse to allow the lambs to suckle, or past mastitis causing one or both sides of the bag to fail completely or partially.
If causes related to management and disease are ruled out, the most common cause of hypothermia and starvation in lambs is maternal inattention. Good mothering ability includes the skill of keeping track of your lambs and not allowing them to starve. In some rare cases, teat size and placement on the ewe can also be a factor. Be particularly attentive for ewes with excessively large, low, or high teats. Sometimes there can be plenty of milk that the lambs simply can’t get to.
Each operation needs to review its death loss totals and determine where it can improve, as death loss is one of the largest drags on profitability in most sheep operations. The overall goal should be to reduce death loss to the lowest practical point, and it makes sense to start with keeping newborn lambs alive and kicking.
