Preventing and Managing Twin Lamb Disease in Sheep

By Bryn Hughes
2 Feb 2026
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Elevated energy demands placed on pregnant ewes in late gestation mean sheep can lose condition and suffer from twin lamb disease. Understanding what twin lamb disease is and recognising the signs of twin lamb disease early can make the difference between life and death for both ewe and lambs. This condition, known as twin lamb disease in sheep, produces ketones as fat reserves are used as an energy source instead of glucose in the bloodstream.

Appropriate and accurate nutrition for ewes in the last 8 weeks of pregnancy is crucial to reduce the incidence of twin lamb disease or pregnancy toxaemia. Regular body condition scoring (BCS) should be carried out by the same individual each time to identify any changes in ewe condition over this period. Farmers should feed ewes according to the number of foetuses carried, making scanning a worthwhile exercise to inform pre-lambing rationing.

What is twin lamb disease?

What is twin lamb disease? This metabolic condition represents one of the most serious threats to pregnant ewes carrying multiple lambs. What causes twin lamb disease is primarily an energy imbalance that occurs in late pregnancy when the demand for glucose increases exponentially due to rapid foetal growth. The foetuses outstrip the ability of the ewe to provide glucose, leading to a deficiency. Twin lamb disease in sheep is most common when twins or even triplets are present, though it can occasionally affect ewes carrying single lambs if they are in poor body condition.

Understanding what causes twin lamb disease helps farmers implement effective twin lamb disease prevention strategies. As the ewe breaks down her body fat reserves to meet energy demands, ketones are produced and enter the bloodstream. High levels of ketones in the blood have serious consequences and will cause the ewe to feel dull and unwell. As levels increase, she is likely to stop eating, which exacerbates the problem and accelerates the progression of twin lamb disease in sheep.

Recognising the Signs of Twin Lamb Disease

Early recognition of twin lamb disease symptoms can significantly improve treatment outcomes. The signs of twin lamb disease typically progress from subtle behavioral changes to severe neurological symptoms if left untreated.

Early Signs of Twin Lamb Disease

The early symptoms of twin lamb disease may be subtle but are critical to identify:

Reduced feed intake or reluctance to come forward at feeding time
Slight dullness or lethargy compared to flock mates
Appearing slightly twitchy or nervous behavior
Mild separation from the main flock
Slightly elevated breathing rate

These early twin lamb disease symptoms indicate increasing ketone levels in the blood and represent the window of opportunity for successful treatment. Farmers who regularly observe their flocks and understand the normal behavior patterns of their ewes are best positioned to spot these early warning signs of twin lamb disease.

Advanced Symptoms of Twin Lamb Disease

As the condition progresses, the clinical signs of twin lamb disease become more pronounced and severe:

Complete separation from the flock
Not grazing or refusing to eat entirely
Not retreating when approached by people or dogs
Apparent blindness or disorientation
Foamy discharge from the mouth and nostrils
Grinding teeth - often a sign of severe head pain
Facial twitching or whole body tremors
'Pear drop' breath - a distinctive sweet smell indicating high ketone presence
Severe depression and weakness
Inability to stand or coordinate movement

Ewes with advanced twin lamb disease are frequently very dull, unable to eat, and unable to stand. These severe symptoms of twin lamb disease indicate that the condition has reached a critical stage. As a result of the rapid breakdown of body fat, affected ewes will usually be very thin. At this stage, attempts to save the ewe and the foetuses are usually unrewarding. Understanding these twin lamb disease symptoms allows farmers to assess the severity and urgency of treatment needed.

Twin Lamb Disease in Sheep Treatment

Treating twin lamb disease requires prompt veterinary intervention, especially once symptoms become apparent. If cases are identified early, twin lamb disease in sheep is likely to be more successful. Early signs may include ewes having reduced feed intakes, appearing slightly dull, or being slightly twitchy and nervous—all signs of increasing ketone levels in the blood.

When treating twin lamb disease, veterinary protocols typically include:

Intravenous glucose solutions to rapidly restore blood glucose levels
Oral propylene glycol as a glucose precursor
Corticosteroids to stimulate appetite and mobilise energy reserves
Supportive care including shelter, warmth, and stress reduction
In severe cases, inducing early lambing may be necessary

It is sometimes necessary to induce an early lambing where dead lambs are likely to be born, but it may save the life of the ewe. The success rate of twin lamb disease in sheep treatment depends heavily on how quickly intervention begins after symptoms appear. You should always seek advice from your vet on the most effective course of twin lamb disease in sheep treatment for your specific situation.

How to Prevent Twin Lamb Disease

Understanding how to prevent twin lamb disease is far more effective and economical than treating the condition once it develops. The key to twin lamb disease prevention is good nutritional management of the pregnant ewe throughout gestation, with particular attention to the final eight weeks before lambing.

Body Condition Scoring for Twin Lamb Disease Prevention

It is crucial to regularly assess the body condition score (BCS) of pregnant ewes as part of a comprehensive twin lamb disease prevention strategy. It is usually very hard to see how much fat and muscle cover there is due to the fleece, but it can easily be assessed by feeling the transverse processes (often called the short ribs) with your hand.

Monitoring the BCS of ewes regularly will ensure that they are not getting too thin, or indeed too fat, at any stage. Target body condition scores for twin lamb disease prevention are:

At tupping: BCS 3.5
Mid-pregnancy: BCS 3.0-3.5
Late pregnancy: BCS 2.5-3.0
At lambing: BCS 2.5-3.0

Regular assessment every 2-3 weeks during pregnancy allows you to adjust feeding before problems develop. This proactive approach is essential for how to prevent twin lamb disease effectively.

Nutritional Management for Twin Lamb Disease Prevention

Pregnant ewes need to be fed according to the number of foetuses present as a critical component of twin lamb disease prevention. It is important to get ewes scanned to check first if they are pregnant, but equally important to get an estimation of the number of foetuses present. Ewes with singles, twins, and triplets then need to be managed as separate groups and fed differing amounts, especially during the later part of pregnancy.

If all ewes are simply fed the same, then those with multiple pregnancies may be at risk of becoming ill with pregnancy toxaemia. Specific feeding guidelines for twin lamb disease prevention include:

Single-bearing ewes: Maintain condition with quality forage and modest concentrate supplementation
Twin-bearing ewes: Increase energy intake by 40-50% in the final 6 weeks
Triplet-bearing ewes: May require up to double the energy intake of single-bearing ewes

This targeted nutritional approach is fundamental to preventing twin lamb disease in flocks with varying litter sizes.

What is the prognosis for twin lamb disease?

The prognosis for twin lamb disease is generally poor to guarded, with outcomes heavily dependent on how early the condition is detected and treated. If caught at the early stage when the ewe is just picking at food and seems lethargic, there's a very good prognosis, and good recovery rates are achievable with prompt diagnosis and treatment. However, clinically affected animals have a poor prognosis even with appropriate treatment, with survival chances dropping to less than 40% once a ewe shows symptoms. Recovery only occurs in about 30% of more severe or advanced cases, even with intravenous energy supplements. If the disease progresses to where the sheep can no longer stand, she has a very poor chance of survival, and without intervention, twin lamb disease can progress over two to four days to blindness, coma, and death. The prognosis for lambs is equally concerning, as only 12% of lambs from ewes with twin lamb disease are born alive, and there's a higher rate of difficult lambings, with 50% needing assistance. The stark difference in survival rates between early and late-stage disease underscores why prevention and early detection are absolutely critical, as the disease can progress rapidly, sometimes within just a day or two, making vigilant observation of pregnant ewes essential during the final weeks before lambing.

Stress Management and Twin Lamb Disease Prevention

Stress and movement can trigger cases of twin lamb disease, especially in very late pregnancy, and great care should be taken to avoid this as part of your twin lamb disease prevention strategy. A number of factors can cause a temporary reduction in feed intakes in pregnant ewes, and this drop in energy can push susceptible ewes over the edge into twin lamb disease.

Key stress factors to manage for twin lamb disease prevention include:

Poor weather: Rainy, cold conditions can reduce feed intake significantly
Housing transitions: Moving heavily pregnant sheep indoors just before lambing can present a significant risk
Handling stress: All handling of pregnant ewes should be calm, quiet, and stress-free
Feed disruptions: Severe weather, such as unexpected snow, can disrupt normal feeding operations and be very serious
Social stress: Seemingly straightforward operations such as moving and mixing ewes can have serious consequences in late pregnancy

The risk of twin lamb disease in sheep will always be much lower if ewes are in sufficient body condition and are being fed appropriately for the number of foetuses they have. Care should be taken to reduce stress and make any changes in good time before lambing starts.

Monitoring Blood Ketone Levels

It is possible to have a blood test taken from a group of pregnant ewes to look at their blood ketone levels. This proactive monitoring can be a valuable tool in twin lamb disease prevention. Blood ketone testing can be a useful indicator of how well the ewes are coping with their diet and whether any adjustments may be beneficial, as well as giving an indication of the risk of twin lamb disease in the group.

Testing should be conducted:

4-6 weeks before lambing
When body condition appears to be declining
After any significant stress event or feed disruption
When weather conditions have been challenging

This monitoring allows you to adjust feeding strategies before clinical symptoms of twin lamb disease appear.

Risk Factors for Twin Lamb Disease in Sheep

Understanding the risk factors helps target twin lamb disease prevention efforts:

Multiple pregnancies: Twins and triplets dramatically increase risk
Poor body condition: BCS below 2.5 at 6 weeks pre-lambing
Inadequate nutrition: Insufficient energy in late pregnancy diet
Sudden feed changes: Abrupt alterations in diet or feed quality
Weather stress: Cold, wet conditions increasing energy demands
Late pregnancy: Greatest risk in final 2-4 weeks before lambing
Previous history: Ewes that have had the condition before
Breed factors: Some breeds may be more susceptible

Conclusion: Prioritising Twin Lamb Disease Prevention

Understanding what is twin lamb disease, recognising the signs of twin lamb disease early, and knowing how to prevent twin lamb disease are essential skills for successful sheep farming. The symptoms of twin lamb disease can progress rapidly from subtle behavioral changes to life-threatening complications, making prevention the most effective strategy.

Implementing comprehensive twin lamb disease prevention through accurate body condition scoring, targeted nutritional management based on scanning results, stress reduction, and vigilant observation will significantly reduce losses. While treating twin lamb disease is possible with early intervention, the best approach remains prevention through proper management of pregnant ewes.

By understanding what causes twin lamb disease and maintaining appropriate body condition and nutrition throughout pregnancy, farmers can protect both ewe welfare and farm profitability. Remember that twin lamb disease in sheep treatment success depends on early recognition of twin lamb disease symptoms, so regular flock observation and body condition assessment should be non-negotiable practices in any sheep operation approaching lambing season.