With the recent cold weather that reduced pasture growth ahead of winter lambing, producers are being warned to watch out for pregnancy toxaemia, or twin lamb disease, in sheep.
Agriculture Victoria Senior Veterinary Officer Dr Paul Beltz said with limited pasture in many areas and cooler conditions, there have been a number of instances of pregnancy toxaemia across the south west and the risk continues to be high for the disease.
“Ewes are most at risk in late pregnancy when their lambs double in size over the last trimester,” Dr Beltz said.
“Pregnancy toxaemia it is caused by ewes not getting enough energy from their diet for the demands of pregnancy.
“Ewes might be in good condition but an increased need for energy for the lambs’ growth, combined with a smaller rumen caused by multiple pregnancies, results in these demands not being met.”
Pregnancy toxaemia often happens in twin-bearing ewes and can follow a drop in nutrition. This commonly occurs when pastures have been eaten out and no supplementary feed is supplied.
“Late pregnant ewes can tolerate low levels of energy if undisturbed but being placed under stress increases nutritional demand,” Dr Beltz said.
Other conditions which may lead to the disease include:
- older ewes or ewes pregnant with twins or triplets
- ewes that have a previous history of pregnancy toxaemia
- cold, wet and windy weather
- extensive grazing situations where the last third of pregnancy coincides with a late break in the season, followed by cold weather leading to little pasture growth
- Short periods without feed such as yarding
- Stress, due to climatic conditions, handling, being chased or management procedures
- Heavy worm infestation
Dr Beltz said the disease progresses over a few days until death.
“Ewes first separate from the flock, and may appear blind; standing still when approached,” he said.
“In the later stages there is marked drowsiness and tremors and spasms of the head, face and neck with the head pulled back or sideways.
“Ewes with pregnancy toxaemia will respond to treatment if this is given at earliest signs. Energy solutions such as molasses or glucose or propylene glycol can be given by drench.”
For further information on pregnancy toxaemia please contact your private veterinarian or local Agriculture Victoria Veterinary Officer or Animal Health Officer.