Metabolic Disease around Lambing

There are two main causes of a down ewe prelamb, pregnancy toxaemia and hypocalcemia which can have similar clinical signs and can present in similar circumstances.

Pregnancy toxaemia (sleepy sickness, twin lamb disease) caused by a negative energy balance i.e., the ewe is unable to supply enough energy for her foetuses as well as meet her own demands. Affected ewes often become drowsy, stop eating, may separate themselves from the flock and if left to progress sit down and die within 2-7 days. A characteristic feature is ‘wool pull,’ where the wool plucks easily. General treatment includes providing energy either in the form of oral ketol or injectable glucalphos but often treatment can be unrewarding, and prognosis is much better if she is still eating.

Risk factors include multiple bearing ewes and severe weather events. Reduce the chance of pregnancy toxaemia by making sure adequate feed is on offer, especially for multiple bearing ewes in the last 6 weeks of pregnancy as they have the highest energy requirement. If pasture is tight, supplementary feed may be required, especially in bad weather. Minimise any time ewes are required to be off feed.

Hypocalcemia (milk fever) is a deficiency of calcium; clinical signs are usually more rapid onset than pregnancy toxaemia and once ewes are down, they usually die within 24 hours. When treated with injectable calcium, they have a rapid recovery. A response to calcium is diagnostic of the condition. Sheep in the last weeks of pregnancy and first few weeks of lambing are most at risk, especially older ewes, ewes held off feed or extreme weather reducing ewe’s feed intake.

Both pregnancy toxaemia and hypocalcemia are preventable and the key to prevention include adequate nutrition and minimal stress (e.g., yarding) in late pregnancy and early lactation.