Pregnancy toxaemia (twin lamb disease)
Pregnancy toxaemia strikes ewes carrying twins or one large lamb, 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 range between 1-5% of single-bearing ewes and 10% or more of twin-bearing ewes.
Energy requirements of a ewe in the end stages of pregnancy are double that of a non-pregnant ewe, while twin-bearing ewes need 2.5 to 3 times the energy needed to prevent a non-pregnant ewe lose weight. 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. Offer good quality hay and oats to the affected ewe if she is able to eat. If ewes do not respond to treatment within 12 hours, they should be humanely euthanised.
Pregnancy toxaemia can be prevented by: