How to differerentiate pregnancy toxaemia and milk fever

Over the last few weeks, plenty of farmers have been reporting deaths amongst their lambing ewes. Its a frustrating situation after carrying these ewes right through summer and autumn, only to lose them AND their lambs.
 
Many things can kill sheep at the break of the season so it’s important to narrow down the possibilities. There are a couple of common diseases that are likely causes: pregnancy toxaemia (twin lamb disease) and hypocalcaemia (milk fever).

Pregnancy toxaemia is a deficiency of energy that affects ewes even in good condition, during late pregnancy, as a result of declining nutrition. Twinning ewes are more susceptible and onset is also triggered by stresses such as yarding, transporting, shearing, etc. If there is very little green feed in your paddocks and the ewes are in the last three weeks of pregnancy, or just started lambing, the most likely cause is pregnancy toxaemia.

Hypocalcaemia is a calcium deficiency or an inability to mobilise calcium reserves.  Stresses such as moving, yarding, or holding off feed, can trigger the disease causing the animal to develop staggers and go down quickly. Ewes in late pregnancy are prone to hypocalcaemia when grazing young, rapidly growing cereal crops or if they have been on cereal grain for prolonged periods over summer without calcium supplements and have just begun to get some green pick after opening rains.

These two diseases are often confused as they both occur in late pregnancy, they can both be triggered by similar factors and they may even occur together. Treatment for one disease will not cause problems if it is the other disease. However, identification of the correct disease is the best way to deal with it.


How to differentiate:

Pregnancy Toxaemia (twin lamb disease) Hypocalcaemia
(milk fever)
Onset Slow with death after 3-7 days, progresses slowly through the mob Fast with death in 6-24 hours, often large numbers of ewes affected
Stage of pregnancy Occurs in late pregnancy, usually in twinning ewes
 Occurs in late pregnancy and early lactation, older ewes more prone
Type of feed Occurs when stock are on a declining plane of nutrition – simply not getting enough to meet their requirements Occurs on lush rapidly growing green feed ie cereals and sour sobs or when animals have been grain fed for prolonged periods without calcium supplements
Symptoms Appears to be blind, blunders into obstacles, stands still when approached, stands away from mob, goes down in natural resting position, dehydration
 Stilted and proppy gait, alert and struggling when approached, muscle tremors, staggers and goes down, often with legs stretched out behind the body
Treatment Drench daily with 120 to 180 ml of Glycerine mixed with equal volumes of lukewarm water. Ketol, Lectade, Ceton and Vytrate are also used. Feed the mob 0.5kg/head of oats or lupins per day for the last month of pregnancy
Injection of Calcium Borogluconate ie ‘Calcigol’ or ‘4 in 1’
Recovery Best to treat while sheep are still alert. If sheep are down recovery is poor Rapid response within 20 minutes
Prevention
 Planning for a decline in nutritional value of paddock feed, hand feeding with adequate energy Ewes should have grain feed supplemented with calcium over summer months prior to lambing

 

It is important to rule out other scenarios when considering stock deaths such as consumption of toxic weeds that they normally wouldn’t eat if they weren’t hungry and enterotoxaemia if sheep have not been fully vaccinated.

For further info contact Brian Ashton, Senior Livestock Consultant, Port Lincoln, 8688 3403.

AUTHOR: Emma McInerney, Research Officer – Grain & Graze, SARDI
CONTACT: Your local Rural Solutions SA Livestock Consultant,
Telephone: 1 300 364 322