As lambing season approaches, it is important to review a condition that can cause considerable economic loss. Pregnancy toxemia is also known as lambing sickness, twin-lamb disease, pregnancy disease and ketosis. This often fatal disease occurs during the last month of pregnancy and is the most commonly occurring metabolic disease of sheep and goats. The good news is, that with careful attention, pregnancy toxemia can be prevented.
Cause: Pregnancy toxemia most commonly occurs in ewes pregnant with twins or triplets. The underlying cause is hypoglycemia (low blood sugar). Unlike other species, sheep and other ruminants do not absorb much glucose from their diet. The glucose they need for brain and muscle function must be made in the liver from other compounds. The growing fetuses also require large amounts of glucose, further stressing the ewe’s metabolism. If the ewe is under-conditioned and/or underfed, they are more at risk. If the ewe is of an adequate condition, but becomes stressed or goes without feed for whatever reason, they are also at greater risk.
Symptoms: Early symptoms of pregnancy toxemia include isolation from the flock, going off feed, becoming unsteady, and having small fecal pellets and a dull appearance. As the disease progresses, symptoms include impaired vision, blindness, convulsions, teeth grinding and labored breathing. Severe cases progress to coma, and death occurs about 80% of the time.
Diagnosis: Most of the time, the above symptoms in a late pregnant ewe are enough to make a diagnosis and start treatment. Late pregnant ewes who go off feed can be tested for ketones in a urine sample. Test strips are available that will turn purple if ketones are present in the urine-indicating ketosis/pregnancy toxemia. If the ewe is down and unable to get up, the prognosis is grave.
Treatment: In mild cases where the ewe is still eating, feeding concentrates may be sufficient to reverse the condition. Oral propylene glycol or corn syrup can be used for quick sources of energy. The dose of propylene glycol is 60-200 ml given three times daily. An oral electrolyte solution can be added at a rate of three-four liters per day. In more severe cases, intravenous dextrose can be used to correct low blood sugar. Intravenous fluids may be necessary for treatment of severe dehydration. If it is suspected that the fetus may have died, antibiotics should be used.
If the ewe’s condition does not improve with medical management, induction of lambing or a caesarian section may be done in an attempt to save the ewe. If the animal is still responsive, and at least day 139 of pregnancy, lambing can be induced with 20-25 mg of dexamethasone. Induction will take approximately 48 hours, which is too long for the severely affected ewe. In those cases, caesarian is the only remaining option.
Prevention: Studies show that late-pregnant ewes require about 50% more feed with a single lamb and about 75% more feed if carrying twins. An appropriate amount of protein and energy needs to be supplied without causing grain overload. A high-quality supply of forage should be supplemented with one pound of grain per ewe daily during the last four to six weeks of pregnancy. It is important to feed yearlings separately to minimize competition. Grain should be introduced gradually with ample space at the feeder.
By: Dr. Meredith Johns
Editors Comment: Ewes that are allowed to become fat in fall are more susceptible. Some work done in Israel showed banamine daily to be more effective than conventional treatment.
