Pregnancy toxemia or lambing paralysis, is an insidious disease that all too many of us are familiar with. The disease often causes devastating losses in near term gestating ewes and does. Many times up to 20 percent of a flock may die with often times, 80 percent of the dams affected to one extent or another (Kimberling, Cleon and Jensen 1988).
The cause of the disease is not well understood but it is associated with an inability of the ewe or doe to keep up with the high energy demand placed upon it by the advanced near-term fetus(s). In general, we seem to see two forms of the disease.
One, in which affected animals are thin or undernourished, and in the other, overweight, fat dams are affected. Typically, what we encounter is a ewe or doe in late gestation (usually the last 2 to 3 weeks) that is weak, uncoordinated, and maybe able to stand only with assistance. Many times these animals seem to be disoriented, they may stagger when walking and may arch their heads awkwardly back over their spines. They may have a sweet ketone smell to their breath. Usually, these animals are thin or very obese. If left untreated, these animals will either die, abort their fetus(s) and die, or abort and slowly recover.
The pathogenesis of the disease is complicated but it is all related to the fact that energy production by the ewe or doe must be in sufficient amounts to meet the demands of rapidly developing fetus(s) and their own maintenance. Dams that are short on groceries will not have enough energy intake from their feed to supply the demand and typically cannot rob enough energy from their fat stores to supply their increasing demand.
Animals that are fat have another problem. Their livers are usually so damaged by infiltrating fat, they can no longer manufacture the glucose needed by the developing fetus(s) in sufficient quantities to supply the glucose needs of the fetus(s) and their own bodies.
Treatment of these animals is very discouraging. Nearly half of the affected animals will often time perish despite the treatment instituted. Usually, when treatment is attempted, it is centered around supplying extra energy in the form of glucose. Propylene glycol (available at all good cigar stores), molasses, and syrup can be used to help those that are still up and eating. Those that are down may need additional care such as intravenous glucose solutions and supportive care. If these measures are unsuccessful, many times the pregnancy is terminated in order to save the doe or ewe, however, many times this is still unsuccessful.
Prevention – Due to the poor prognosis of the animals that become affected, it is much more economical to prevent this disease than to treat those that become ill. Prevention is aimed at preventing and correcting nutritional problems before the last trimester of pregnancy. Ewes and does with multiple pregnancies should be fed a ration almost twice or more above the normal maintenance level during the last trimester. Those with singles should be fed approximately 1.5 times maintenance levels. Animals should be handled and condition scored to evaluate their nutritional needs. Those that are thin or with multiple fetuses should be placed on a higher plane of nutrition and separated from the others. Management tools such as real time ultrasound (which can determine fetal numbers if done between 45 and 90 days of gestation), condition scoring and ration balancing are all needed to help prevent this disease. If you feel your herd would benefit from a preventative program, you should talk to a veterinarian for help in establishing one.