Antimicrobial prophylaxis post-amniocentesis procedures in cattle: A randomized controlled equivalence study

Amniocentesis is a routine procedure utilized on several species including human, equine, and bovine patients. Early assessment and discovery of new genetic traits in the cattle industry are highly desirable in order to accelerate genetic gain by shortening generational intervals. One of the main concerns from this procedure is the introduction of pathogenic bacterial contamination into the amniotic cavity thereby increasing the risks of spontaneous pregnancy losses post procedure. In this randomized controlled equivalence study, we have tested the effect of antimicrobial prophylaxis on the incidence of spontaneous abortions and contrasted it to untreated individuals post amniocentesis. On the treated group (n = 67) all heifers remained pregnant whereas 1 of the untreated group (n = 65) resulted in a spontaneous abortion during the study period. The latter represents 1.54% of pregnancy losses attributed to the risk associated to the amniocentesis procedure. However, the probability of inducing spontaneous abortion from the technique itself is not different to that of the contemporaneous population (n = 694) not undergoing amniocentesis viz., 1.59%. Following a two-tailed distribution, statistical analyses showed no significant differences across treatments (Fisher's exact test P = 0.49). The current prospective study indicates that performing amniocenteses on cattle have resulted in similar spontaneous pregnancy losses comparable to those of pregnant heifers without undergoing amniocentesis and regardless of antimicrobial use. In conclusion, prophylactic antimicrobials may not be applicable within the cattle amniocentesis framework.