Do you have high levels of twin bearing ewes? Is your farm a bit tight on feed this year? Then your flock might be at risk of sleepy sickness (AKA pregnancy toxaemia or twin lamb disease).
Sleepy sickness is a metabolic disorder of sheep seen in late pregnancy and is caused by a mismatch in the requirements of the ewe and the feed supply. On some farms it can be due to low levels of nutrition offered (especially in the last six weeks of pregnancy) but can also occur in multiple bearing ewes even with adequate feed levels. In these ewes the uterus fills the abdomen compressing the rumen, reducing the amount of feed that the ewe can eat, leading to reduced energy levels. Stressful events such as shearing or poor weather can also predispose to sleepy sickness.
Typically ewes are depressed, ‘off-feed’ and reluctant to move. Head pressing, apparent blindness and “wool pull” (where the wool plucks easily off the live animal) may also be present. In more advanced cases, the ewe may go down, stargaze, become comatose and die. Also, affected ewes will often abort dead lambs. It is common for many ewes to be affected by sleepy sickness in late pregnancy when a flock is put at risk.
Treatment is most successful in the early stages of the syndrome. Affected ewes should receive a single injection of 100 mL of Glucalphos subcutaneously. Additionally give 60-120 mL of Ketol orally for three to five days. Ensure water and feed are available at all times and provide oral electrolytes to combat dehydration (e.g. 2 L of Revive two to three times daily). If the ewe is recumbent with “wool pull” and not eating then the prognosis is poor. Even with treatment, recovered animals commonly have still-born lambs.
Prevention is by feeding pregnant ewes on a rising plane and surplus stock (dry ewes etc.) should be removed from the farm to increase the feed available. Multiple bearing ewes should be separated from singles and fed preferentially during late pregnancy (identify multiples with scanning). If there is still not enough feed available then supplementary feed should be provided (hay, grain or a crop). It is also important after a sudden fast to avoid further stress such as mustering and holding off feed for long periods.
Pregnancy toxaemia is a common condition, talk to your veterinarian about how to implement management changes on your slice of paradise to reduce the risk of your flock being affected.