Pregnancy Toxaemia

Avoid Losing Stock To Pregnancy Toxaemia
Pregnancy toxaemia is a metabolic disorder in ruminants that is a result of a high carbohydrate or energy demand by the foetus exceeding what the mother can supply from her diet during the last trimester of pregnancy. The condition is amplified by multiple or large foetuses, poor quality feed that is low in energy, protein or high in poorly digestible fibre. Any health conditions that increase the energy demand or decrease the animal’s ability to take in nourishment (eg. Parastitic burdens, poor teeth or lameness) will further increase the rise of pregnancy toxaemia.

Pregnancy toxaemia or ketosis is caused by abnormal metabolism of carbohydrates and volatile fatty acids. It is a highly fatal disease of sheep, goats and cattle in late pregnancy and is characterised by fatty infiltration of the liver, ketone bodies in the blood and urine, hypoglycaemia and low liver glycogen. The disease is also known by names such as twin lamb disease, lambing sickness, acetonaemia, fat cow syndrome and fatty liver disease of cattle (Hungerford, 1990).

In cattle Pregnancy Toxaemia is also known as: Fat Cow Syndrome, fatty liver disease of cattle, acetonaemia of cattle and ketosis.

Pregnancy Toxaemia is a form of ketosis a disease that occurs when the breakdown products of fat called ketones build up in the brain and become toxic. Pregnant cows require a great deal of ready energy in the form of glucose to maintain their developing calves. Glucose is produced in the liver from the feed absorbed via the rumen. If there is a nutritional shortfall then fat deposits are mobilised and carried to the liver in the blood, for the liver to convert to glucose. A certain amount of glucose is needed by the liver to enable it to use the incoming fat. If the fat is arriving faster than the liver can make glucose the fat starts to build up in the liver. Consequently, the liver becomes enlarged, fatty, pale and chemicals are produced called ketones that build up to excessive levels in the blood. The excessive Ketones affect brain function and the animal stops eating and eventually will die.

The condition is most common in over-fat cows in the last two months of pregnancy. Pregnancy Toxaemia can affect pregnant cows of all ages as well as occasionally affecting cows that have recently calved. Cows that are carrying twins are particularly susceptible due to the greater energy requirement and at the same time they have internal space limitations that restrict feed intake. Cows that are suffering from excessive parasitic burdens, lameness and poor teeth are also highly susceptible. Stressors such as sudden cold, wet weather, yarding or travelling may also stimulate the disease.

Pregnancy Toxaemia is also known by these names in sheep: Twin Lamb Disease, Pregnancy Disease, Ketosis, acetonaemi or Lambing sickness.

The actual cause of the disease is a severe lack of glucose in the bloodstream due to a combined deficiency of food and the demands of pregnancy. Abnormal fat and carbohydrate metabolism results and leads to the presence of ketone bodies in the bloodstream. This results in brain damage and nervous derangement. It is associated with exhaustion of the carbohydrate reserve in the liver. As seen in the condition in cattle, fat is used as a major maternal energy source and ketones are produces as a consequence. As more fat is mobilised, the more ketones are produced. Over a prolonged period of severe lack of adequate nutrition, the level of ketones become toxic and leads to a further reduction of feed intake and eventually clinical signs of pregnancy toxaemia.

Females with a poor body condition score or those that are over-fat or carrying more than one foetus are most at risk of developing pregnancy toxaemia. Other predisposing causes of the disease are stress related such as: A rapid drop in the plane of nutrition caused by sudden starvation such as seen when yarding overnight, shearing, drought, transport, heavy droving and to a less extent rapid changes in weather condition. Other health factors such as old age, poor teeth, heavy parasitic burdens and conditions such as footrot will favour the onset of the disease.

Signs and Symptoms to look out for in Cattle

  • Pregnant
  • Reduced appetite or absent
  • Depression and lethargy
  • Isolate themselves from the herd
  • Nasal respiration
  • Sweet acetone-like odor detectable on their breath
  • Neurological signs (staggering, aggression, delirium)
  • Recumbent (downer cow) 2 days to 2 weeks before they die
  • Death

Signs and Symptoms to look out for in Sheep

  • Pregnant
  • Depression/drowsiness/dopiness
  • Reduced appetite or absent
  • Separation from the flock
  • Nasal discharge
  • Apparent blindness
  • Chewing, teeth grinding or vigorous licking movements may be observed
  • Neurological signs (staggering, wandering aimlessly, star gazing)
  • Sweet acetone-like odor detectable on their breath
  • Sternal recumbency (sitting on their sternum)
  • Head pulled back or sideways
  • Convulsions – Death

Prevention Strategies
The best prevention strategy is to ensure that pregnant animals receive an adequate plain of nutrition, especially during the last month of pregnancy. This means that all of their nutrient requirements are being met for energy, protein, fat, minerals and vitamins.

During the last few weeks of gestation the foetus will grow rapidly, which is followed by parturition and then lactation all of which have huge nutritional demands and can place the mother in a negative energy balance.

In most cases, supplementary feeding will be required (especially in the last 6 weeks of gestation) in the form of energy dense ingredients such as cereal grain or lupins. The energy dense feed helps to overcome the energy deficiency resulting from lower feed intake during the final trimester. In addition to meeting energy and protein requirements, it is essential that sufficent levels of macro and trace minerals are provided to help meet the greater requirements of pregnancy and later for lactation. There is also some evidince supporting the use of supplements including monensin or lasalocid to help improve energy metabolism.

Besides carefully managing and monitoring the diet it is important to avoid getting ewes and cows too fat (i.e. fat score greater than 3.5-4) or too thin (i.e. fat score less than 2-2.5) in late pregnancy.

In addition to managing nutrition an important prevention strategy is trying to avoid stressful management practices such as mustering, yarding, shearing etc., in heavily pregnant animals.

For further information on how AgSolutions can help you manage your pregnant stock please contact us
on 1800 81 57 57.

Casburn, G. (2016). Pregnancy toxaemia in breeding ewes. Wagga Wagga: Department of Primiary Industries NSW Government.

Cebra, C. (2019, May 22). Pregnancy Toxemia in Cows. Retrieved from MSD Veterinary Manual:

Hungerford, T. (1990). Diseases of Livestock (Vol. 9th Edition). Roseville, NSW, Australia: McGraw-Hill Book Company Australia Pty Ltd.

Menzies, P. (2019, May 22). Pregnancy Toxemia in Ewes and Does. Retrieved from Merck Veterinary Manual:

Merck Sharp & Dohme Corp. (2009-2015). The Merck Veterinary Manaual. Kenilworth: Merck and Co, Inc.

Sadjadian, R., Seifi, H. A., Mohri, M., Naserian, A. A., & Farzaneh, N. (2013). Effects of monensin on metabolism and production in dairy saanen goats in periparturient period. Asian-Australasian journal of animal sciences, 26(1), 82–89. doi:10.5713/ajas.2012.12347