Simply put, hypothermia means that the body temperature has dropped to the point where life is in danger. The most common cause of this is when babies are born outside in cold and oftentimes wet weather and are not dried quickly by the mother. The best way to prevent this, of course, is to have a nice warm dry sheltered area in which the does can deliver and to be there to make sure that the kids are quickly dried off and get some nice warm colostrum going into their little tummies.
But accidents do happen despite our best intentions. Should this happen to you, immediately take the kid into the house. There is no way that sticking a wet and nearly frozen kid under a heat lamp is going to cure anything. It will merely boil the water on the skin and add to the problems. (Never warm a WET animal!)
If the temperature is over 102 degrees, then you need to re-evaluate the diagnosis. Temperatures between 98.6 and 102 indicate "mild" hypothermia if the kid is less than 5 hours old and can usually be taken care of by briskly drying it off and feeding some colostrum. Anything below 98.6 should be considered an emergency.
Any one of several methods will restore the body temp to normal. One that seems kind of funny but which really does a good job is to immerse the kid in a bucket of water. You can start with the water about the same temp as the kid and gradually raise the temp to 100 degrees. Raising the temperature too rapidly by any method can cause the baby to go into shock. After the kid’s temp reaches and maintains 100 degrees, keep the kid in the water for about 10 more minutes. Then remove and dry it and check frequently to make sure that it can maintain the temperature on its own. Dunking the kid in water will remove most of its natural odor and the mother may tend to reject it when you take it back outside. So rub it against one of the other kids before giving it to mom. Some folks take all the kids away from the mom while the weak one is being administered to. Then they are all returned at once, which can confuse the mom a little. An even better way to immerse it is to put the entire baby, except for the head, in a plastic bag. That way the body does not get so wet and the natural odors are preserved.
Warm water enemas can be of help. Surrounding it with warm towels or hot water bottles are also good ideas. Feeding some nice warm colostrum is very helpful.
There is a procedure for injecting glucose into the peritoneal cavity which we may present later. It is probably not something that the amateur would be trying.
Some people use hair dryers with great success but I’m not sure I like that method.
Whatever method is used, the body temperature should be monitored with a thermometer, which is more accurate than the finger in the mouth approach.
There are other causes of hypothermia, mostly related to nutritional deficiences, and these problems must also be dealt with in order to have a long term resolution. These can occur at any age.