PREGNANCY TOXAEMIA (SLEEPY SICKNESS)
Pregnancy toxaemia strikes ewes carrying twins or triplets, usually in the last few weeks before lambing. It is caused by negative energy balance, as the ewe is unable to supply enough energy to meet her own demands as well as those of the fast-growing foetuses. The incidence of the disease may typically occur in 10% or more of twin and triplet bearing ewes.
Energy requirements of a ewe in the end stages of pregnancy are double that of a non-pregnant ewe, while twin and triplet bearing ewes need 2.5 to 3 times that energy. If sufficient energy is not supplied (by pasture or supplements) the first consequence will be reduced birthweight of the lamb, then breakdown of the ewe’s body reserves. If this is accompanied by bad weather or other stressors, the ewe will go into energy deficit and suffer depression, then lie down and die within 2 to 7 days.
Treatment
Oral solutions for pregnancy toxemia. These contain propylene glycol and are administered like a high-volume drench. e.g. Vytrate 160 mL of undiluted concentrate every 4-6 hours. Injectable solutions are also available. Response to treatment is usually slow, particularly if the ewe’s condition is advanced. If ewes do not respond to treatment within 12 hours, they should be humanely euthanised.
Pregnancy toxaemia can be prevented by:
Checking ewe body condition in mid pregnancy and not allowing them to become ‘overfat’ i.e. try to keep average BCS below 4.
Ultrasound pregnancy testing all ewes and separating empties, singles and twin-bearing ewes.
Giving twin and triplet bearing, older ewes and early-lambing ewes preferential or supplementary feed, especially in the final six weeks prior to lambing.
Avoiding all management procedures that involve tipping sheep up (e.g. crutching, involve shearing, foot-paring) in the six weeks prior to lambing, and other procedures (drafting, drenching, vaccination) in the two weeks prior to lambing.
Avoiding all procedures (mustering, yarding etc.) that prevent ewes from feeding for more than 12 hours.