Pregnancy Toxaemia (Twin Lamb Disease)

Cause

Pregnancy Toxaemia is a metabolic disorder where the body's energy requirements are not being met, resulting from a significant decline in the level of nutrition. In the final two months of a ewe's pregnancy, 70% of the lamb's growth is taking place. It is therefore particularly important at this time to make sure the ewe has enough good feed to keep her and her lamb going. Ewes carrying twins are more often affected, but ewes carrying single lambs can also get the disease. In Tasmania the crucial period is winter when pastures are short and often of poor quality making it difficult for the ewe to get sufficient energy intake. Stressful events like worms, feet problems, mouth problems, yarding and transport can bring on Pregnancy Toxaemia. Late pregnant ewes should not be without feed for longer than 4 hours.

Signs

Separation from the flock	Death 5 - 7 days after the first signs
Standing still when approached	Blundering into objects when moved
Drowsiness	Head pulled back or sideways
Standing in water lapping	Thick yellow discharge from the nose
Apparent blindness	Tremors and spasms of head, face and neck muscles

Treatment

For any treatment to be successful it must be given early. As a simple guide, place some grass in the ewes mouth. If she chews the grass she is worth treating, if not, treatment is unlikely to be successful and the animal must be humanely destroyed. Consult your veterinarian regarding the best options for diagnosis and treatment.

Once individual ewes need to be treated, remember the rest of the mob is in trouble and action needs to be taken now. It is far better to prevent Pregnancy Toxaemia than to treat or control it:

• 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, or if not responding to treatment, she must be humanely destroyed.

For valuable ewes, caesarean section may be considered to remove the demand for glucose.

Prevention

Ideally, ewes should maintain their bodyweight throughout pregnancy. Ewes carrying more than one lamb require a gradual increase in feed during the last six weeks of pregnancy. In some situations, consideration may be given to pregnancy testing all ewes to identify single-bearing and multiple-bearing ewes so that they can be differentially fed. Seek assistance from your vet or adviser in developing a feeding strategy.

Take special care when mustering and yarding ewes in late pregnancy so that they are not off their feed for too long. Also, don't suddenly change the type of feed because the rumen bacteria may not adapt to the new diet.