Cause
Pregnancy Toxaemia in sheep is a metabolic disorder where the bodys energy requirements are not being met, resulting from a significant decline in the level of nutrition. In the final two months of pregnancy 70% of the lambs growth is taking place. It is therefore particularly important at this time to ensure the ewe has sufficient quality feed available. Whilst ewes carrying twins are more often affected, pregnancy toxaemia can also affect single-bearing ewes.
In Tasmania the period of highest risk is winter and early spring when pastures are short and often of poor quality, making it difficult for ewes to consume sufficient energy. Pregnancy Toxaemia can be triggered by stressful events including adverse weather conditions, parasite burdens, lameness, yarding or transport. Late pregnant ewes should not be held off feed for longer than 4 hours. Ewes that are fat (condition score 4/5 or 5/5) are at increased risk of developing pregnancy toxaemia.
Signs
Signs of pregnancy toxaemia include:
Separation from the flock
Standing still or remaining recumbent when approached
Drowsiness or apparent blindness
Standing in water lapping
Head pulled back or to the side
Discharge from the nose
- Tremors and spasms of the head, face and neck muscles
Treatment
Unless given in the early stages, treatment of pregnancy toxaemia is rarely successful. The prognosis for ewes showing obvious symptoms, who are no longer eating when feed is offered or are recumbent is poor and consideration must be given to humane euthanasia. Veterinary advice is recommended. Pregnancy toxaemia can be confused with hypocalcamia, low blood calcium levels, for which treatment is more frequently successful. For valuable ewes, caesarean section may be considered to remove the demand for glucose.
Treatments for individual ewes suffering pregnancy toxamia include:
Glycerol (Glycerine) given orally 100ml twice daily
Glucose, 100ml of sterile 6% solution given under the skin daily
Glucose Solution, 100 - 200ml given orally twice a day
In all cases continue treating the ewe until she recovers. If the ewe is not responding to treatment, she must be humanely destroyed.
Prevention
A single case of pregnancy toxaemia is a warning to review the mob and provide additional feed or remove risk factors where possible. Prevention of cases is far better than attempting treatment.
Ideally, ewes should maintain their bodyweight throughout pregnancy. Ewes carrying multiple lambs require a gradual increase in feed during the last six weeks of pregnancy. Consider pregnancy scanning so feed resources can be managed and prioritised for multiple-bearing ewes. Seek assistance from your vet or agronomist to develop a feeding strategy.
Monitor ewes in late pregnancy regularly and minimise the stress associated with mustering and yarding. Avoid extended periods off-feed and any sudden changes to feed rations.