Animal Health & Welfare

Dystocia is a contributory factor in the deaths of ewes and lambs at lambing time. Dystocia occurs when the ewe experiences a prolonged labour and/or has difficulty delivering her lamb(s) without assistance.

This may be because the lamb is incorrectly presented (about 10-15% of lambs may be incorrectly presented and most will need assistance to be delivered) or because of a mismatch between the size and shape of the lamb and the ewe’s pelvis.

Predisposing factors for dystocia are:

• Lamb presentation – the most common incorrect presentations occur when one leg or two legs are back and the lamb is head first ('hung')
• Lambs are heavy relative to the breed, and size and age of the ewe
• Single lambs experience more birth difficulty than other litters sizes: they are heavier and more likely to be incorrectly presented than twin lambs
• In some breeds male lambs have more dystocia
• Some breeds, or lines within breeds, have greater dystocia problems - it may be possible to select for ewes and rams that produce easily delivered lambs
• Labour is longer in first time mothers, although they do not necessarily have more birth difficulties if given sufficient time to progress
• Ewes which are too fat (overgrowth of foetal lamb) or too thin (ewe may become exhausted during delivery) can experience more problems
• Stress or disruption during labour causing the ewe to stop pushing can prolonged labour, increasing the chance of exhaustion or lamb hypoxia (lack of oxygen).

Assisting ewes with difficult deliveries:

• Do not attempt to assist a ewe too early before the cervix is fully open - this can cause shock, haemorrhage, injuries and infections
• Do not assist the ewe unless it appears that she will have lambing problems as any internal manipulation can increase the risk of infection
• Ensure that high standards of hygiene are adhered to - use lambing gloves or wash hands thoroughly before starting
• If lambs need to be manipulated use plenty of lubricant to avoid tearing tissues, causing haemorrhage and infections
• Lambs can be delivered either forwards (both forelegs extended, nose lying along the legs) or backwards - do not try to turn a lamb around
• For other presentations the lamb should be gently manipulated to achieve a normal delivery (breech to backwards; all others to forwards)
• Allow plenty of time to correct presentations; lambs should be returned to the uterus for manipulation, there is insufficient room in the birth canal for lamb presentations to be corrected.
• Inexperienced lambers should seek advice from a vet or experienced shepherd if they have any uncertainty about how to proceed - excessive manipulations and interventions can cause shock, injury and infection
• Excessively large lambs may need to be delivered by Caesarean section by a vet; prolonged attempts to deliver the lamb through the birth canal should be avoided.

After care

• Lambs born after difficult deliveries, particularly backwards, may need suction to clear fluid from the lungs
• Ewes that have been subject to internal examinations may develop infections and require antibiotic treatment
• Ewes that have had difficult deliveries may be less likely to express good maternal behaviour so require extra attention to ensure good ewe-lamb bonding
• Lambs born after difficult deliveries may be slower to stand and suck and may require extra attention to ensure adequate colostrum intake
• Lambs born after difficult deliveries may have more difficulty maintaining body temperature so will need attention to prevent chilling