Causes of perinatal death in lambs in Oppdal and Rennebu, Norway
© Dragset et al; licensee BioMed Central Ltd. 2007
Published: 12 December 2007
The frequency of stillbirths in flocks registered in the Norwegian Sheep Recording System (NSRS) is increasing. In 2001, 3.4% of born lambs were registered as stillborn, in 2006 the number had increased to 4,1%. Some farmers also report seeing more lambs that are weak at birth and die within a few hours. Post mortem examinations are not frequently carried out, unless there are large losses in the flock. The causes of stillbirths and death in weak lambs are thus to a large extent unknown in the "average flock". On this background, a study was carried out during the lambing season 2006, in order to identify causes of perinatal death in 9 herds in Oppdal and Rennebu in the county of Trøndelag.
Materials and methods
Characteristics of the nine study herds
No. of ewes
No. of born lambs per ewe (2006)
% stillbirths (2006)
No of lambs included in the study
Characteristics of the 74 lambs included in the study
Time from birth to death:
0–42 hours. Less than 1 hour in 46 lambs
Mean age of mother:
3,2 years (min 1, max 7)
Mean size of litter:
2,6 (min 1, max 4)
Mean birth weight:
4,02 kg (min 1.5, max 6.6)
The most common findings at the post mortem examinations were no detectable changes (n = 28) and trauma (n = 21). Unspecific changes (subcutaneous oedema and fluid in body cavities) were also common (n = 13). Other diagnosis were congenital malformations (n = 5), infections/enteritis (n = 5), drowning (n = 4) and torsion of the abomasum (n = 1). Two lambs were mumified and two lambs were cadaverous.
There was no difference in body weight between lambs with trauma and lambs with no detectable changes. Toxoplasma gondii was not found, and all lambs were negative for border disease virus.
Discussion and conclusion
Infections are not common as a cause of perinatal death in lambs in these herds. In many lambs no specific cause of death could be identified. This may indicate that the lambs died during birth, or died short time before birth due to impaired function of the placenta. The relatively low mean birth weights in the dead lambs also indicate that impaired function of the placenta can be a contributing factor. Analysis to differentiate between impaired function of the placenta and death during birth, were not carried out. However, this should be included in new studies.
Trauma can be caused by complications at delivery, as well as attempts of the mother to make the weak lambs stand up. The trauma (e.g. broken ribs) may thus not be the actual reason why these lambs died.
Further investigations are needed to gain more knowledge on causes and prevention of perinatal death in lambs.
This article is published under license to BioMed Central Ltd.