Factors associated with ewe and lamb survival, and subsequent reproductive performance of sheep undergoing emergency caesarean section.

Abstract

Clinical records of all 212 ewes undergoing emergency caesarean surgery at a veterinary teaching hospital between January 2008 and December 2019 were evaluated retrospectively. Their age ranged from 1 to 10years (median=4years), with German merino the predominant breed (48.1% of cases). The most frequently diagnosed indications were insufficient cervical dilatation (n=94, 44.3%), uterine torsion (n=50, 23.6%), foetopelvic disproportion (n=31, 14.6%) and vaginal prolapse intra partum (n=11, 5.2%). Fifty-four (25.5%) of the 212 ewes additionally suffered from one or more concurrent, pre-existing conditions. Overall ewe mortality until hospital discharge was 10.8% (23/212), and 3.8% (n=6) for the 158 ewes without a history of concurrent disorders. Mortality during hospitalization increased to 31.5% (17/54) for those with pre-existing conditions. Total lamb mortality was 49.1% (173/352) until hospital discharge. Pre-existing conditions (p=.001) and the presence of post-surgical complications (p=.025) were identified as significant factors influencing dam mortality, while delayed presentation for veterinary attention with an observed duration of labour of >12hr was identified as the most influential factor on total lamb mortality (p=.010). The presence of dead or emphysematous foetuses was not significant for ewe mortality. Follow-up information on further outcomes was available for 156 (82.5%) of the 189 discharged ewes. Eighty-nine animals (57.1%) were re-bred in the following season and achieved a 93.3% (83/89) pregnancy rate, while the remainder had either been slaughtered (n=56, 35.9%), sold (n=5, 3.2%) or had died of unknown causes (n=3, 1.9%). The subsequent incidence of dystocia was 15.6% (n=12) in the 77 ewes with available information on lambing ease. Adequate management of underlying conditions and timely intervention are important factors for best possible short-term outcomes. In the long term, the subsequent pregnancy rate was good and the incidence of subsequent dystocia was within the normal range.