What is Pregnancy Toxaemia?

Preg Tox is basically due to lack of energy in late pregnant ewes when the lamb (often 2 or 3 lambs) take more energy than the ewe can provide. The lack of energy is caused by a combination of poor feed in late pregnancy, decreased rumen capacity due to the size of the lambs in the belly and a dramatic increase in energy requirements. The energy and protein requirement for a ewe with twin lambs in the last few weeks is roughly double maintenance.

To provide energy, the ewe starts to breakdown body reserve especially fat, however, the liver cannot cope with the increased fat levels. The blood sugar (glucose) levels fall dramatically and the ewe does not have enough energy to function normally – especially the brain, muscles and there is kidney damage.

Signs of pregnancy toxaemia?

  • The disease usually appears over several weeks in a percentage of the mob:
  • ewe is separated from the mob
  • ewe is drowsy or comatose
  • ewe is not eating
  • nervous system signs – tremors, blindness
  • lying on their side for 3–4 days
  • death 3–4 days later

A sudden reduction in feed due to rough weather, transport, yarding, other diseases and handling can tip ewes with a low grade disease showing no sign of a problem into a ewe with full signs of preg. tox. This means if you have a few cases of preg tox, it is an indication the whole mob may be underfed, even if only a few animals are showing signs.

Which sheep are most at risk of pregnancy toxaemia?

  • ewes in late pregnancy especially with twin lambs
  • early lambing flocks when there is a late break and stubbles/dry feed have deteriorated
  • ewes feeding on new green pasture high in water and low in dry matter and nutrients
  • ewes that stop eating during extreme weather.

How can a vet help?

Especially in the later stage, preg tox can look similar to other disease such as milk fever, severe mastitis etc, so getting a diagnosis is important. Early diagnosis of the disease and treatment are essential to prevent further progression. A vet can perform several tests on a live animal to diagnose pregnancy toxaemia or do a post mortem on a freshly dead ewe. A vet may consider inducing the pregnant ewe to birth or performing a caesarean section.

Treatment for pregnancy toxaemia

Unfortunately, if the ewe has progressed to the down/coma stage, treatment is unlikely to work. In the early stages, especially if the ewe is still standing, a product containing propylene glycol may be successful.

Prevention of pregnancy toxaemia

  • Good nutrition and
  • Careful management
  • Lambing ewes require feed on offer of more than 1500 kilo of dry matter per hectare during lambing.
  • If this is not available, provide a supplementary source of energy, such as good quality hay and grain. However, avoid making sudden changes to their feed or causing short sudden periods of starvation such as during yarding.
  • If extreme weather conditions cause ewes to stop eating or become stressed, provide supplementary feed. Take care to avoid grain poisoning by introducing grain slowly.
  • identify twin mothers using pregnancy scanning and then to separate and preferentially feed them to minimise the development of pregnancy toxaemia.