The influence of anaesthesia drugs on puppy vitality after caesarean section: a systematic review

To review and systematically analyse the literature describing the effects of anaesthesia drugs on puppy vitality scores or survival in dogs undergoing caesarean section. Overall 13 randomized controlled trials (RCTs) involving 1978 puppies were included. A comprehensive search using PubMed, Embase and Scopus databases was performed from 1970 until September 2024 to obtain nonrandomized and RCTs examining the effects of anaesthetics on puppy survival rates or vitality scores after caesarean section in dogs. Only studies in English were screened. Search terms included: 'c-section' or 'caesarean section' and 'anaesthesia' and 'dog'. Two authors independently searched, classified and extracted the data. Studies were included if they evaluated the effects of anaesthesia drugs in dogs undergoing general anaesthesia and puppy survival or vitality scores. The level of evidence was scored according to the Oxford Centre for Evidence-based Medicine criteria, and a modified criterion score was used to assess the risk of bias based on the SYRCLE risk of bias tool and the SIGN checklists. Methodological characteristics varied considerably between studies, including drug doses, titration of anaesthetics, anaesthesia monitoring and puppy outcome scores. Ten studies assessed puppy vitality by using a modified Apgar score (AS). A high risk of bias was identified in six studies, whereas three had a low risk of bias. The scarcity of methodologically consistent studies and the quality of data limit identification of an optimal anaesthetic regimen to improve puppy survival. Low doses of morphine, methadone, dexmedetomidine or meloxicam preoperatively did not produce a significant impact on puppy vitality. Ketamine-midazolam, etomidate or thiopental appear to worsen immediate neonatal outcomes. No difference in neonatal survival was found between alfaxalone and propofol, but AS were higher with alfaxalone than with propofol immediately after birth. The use of injectable anaesthetics for maintenance of anaesthesia led to lower puppy vitality.