Development of a surgical technique for long-term catheterisation of bovine fetuses

The aim of this study was to further develop and extensively describe a surgical technique in order to realise long-term fetal blood sampling in the bovine species. Eleven Holstein-Friesian 6- to 8-month pregnant cows (4-10 years old) were used for this study. Gestational age on the day of surgery varied from approximately 180 days (n = 1) to 240 days (minimum: 232 days, maximum 252 days; n = 10). The fetal medial tarsal artery was catheterised in pregnant cows with a polyvinyl catheter in dorsal recumbency under general anaesthesia. Although 5 out of 11 operations (45.5%) performed between 232 and 252 days of gestation were lost due to different causes mainly associated with peritonitis and septicaemia, the mean interval between operations and calvings was 42.5 days (between 27 and 95 days). It is important to emphasise that a well-trained surgical team is needed for bovine fetal cannulation in order to be able to decrease the risk factors during the operations. Due to the fact that after 5 unsuccessful cases none of the pregnancies were lost, this skill can be reached, and our technique can enable bovine fetal blood sampling for long-term endocrinological and physiological investigations before and during parturition.