Milk Fever in Sheep; Differences with Milk Fever in Cows
Also known as hypocalcaemia, milk fever in sheep is a preventable disease. Milk fever in ewes differ from milk fever in cows in that most cases occur before lambing (although it may occur from 4 weeks before, to 6 weeks after lambing). In cows most cases occur AFTER calving. There is another difference: In cows, a diet high in calcium during the dry period (before calving), has an inhibitory effect on calcium mobilisation from the bone, leading to a possible calcium deficiency shortly after calving. Sheep do not seem to share this problem with cows and a diet with sufficient calcium should be fed during the 6 weeks leading up to lambing to ensure that milk fever cases are controlled.
Cause
Milk fever in sheep occurs when the body is unable to mobilise sufficient calcium from the bones to maintain the calcium level in the bloodstream. During the 3 weeks leading up to calving, the skeleton of the unborn lamb(s) drains the ewes calcium reserves and it is especially during this time that a diet with the correct calcium : phosphorous ratio should be available. Consult a nutritionist for help with this. Ewes carrying twins are more susceptible to milk fever. The condition may also occur when oxalates bind the calcium in the blood, rendering the calcium unavailable for use by the ewe. This usually happens when the animals consume oxalate containing plants such as elephant`s ear or yellow sorrel.
Symptoms
Milk fever in sheep often occurs in flock outbreaks, though it is possible for only one or two ewes to be affected. Up to a third of the flock can be affected, though the average is usually nearer to 5%.
Symptoms include:
- Drowsiness
- Salivation
- Stiff gait
- Muscle tremors, although this symptom is more commonly seen in goats.
- Depression
- Stretched-out head with chin on the ground and legs stretched out or folded underneath the animal
- Rapid breathing with foaming at the mouth
Treatment
Administer calcium intravenously or inject a calcium solution subcutaneously. Animals may die if it is not treated as soon as possible. When detected early, oral supplementation with feed that is high in calcium should be sufficient. If the ewe is unable to eat, it is important to treat her with an injectable calcium solution. If the animal does not show signs of recovery within hours of calcium treatment, the ewe may have ketosis in addition to milk fever. Dextrose intravenously and/ or propylene glycol orally and possible glucocorticoid treatment will help for ketosis (energy deficiency)
Prevention
Provide feed with enough calcium during the last 6 weeks of gestation until 4 weeks after lambing. Low-calcium feeds include low-quality hay, grains, and straw. If sheep are penned out of sunlight for an extensive period, they may suffer from vitamin D deficiency. This, in turn, reduces the uptake of calcium in the gut. Supplementation with vitamin D, and with feed that contains sufficient calcium for the period 6 weeks before to 4 weeks after lambing will help prevent Milk fever.
Animals that are too fat, increases the risk of reduced dry-matter intake due to limited space in the abdominal cavity. This in turn leads to low levels of calcium and energy intake with the possible development of milk fever and / or ketosis (energy deficiency). Ewes carrying multiple lambs should receive more calcium. Older ewes struggle with calcium absorption. Monitor the flock and provide extra calcium to high-risk animals. Make sure ewes in late stages of pregnancy are never without feed for more than 12 hours.
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