Effect of Daily Serial Phlebotomy in a Rhesus Macaque (Macaca mulatta) Model of Flavivirus Vaccine

Blood collection and analysis in research animals is a necessary component of experimental studies, data analysis, and health monitoring. Current maximum volume recommendations for one time blood collections are dependent on species, weight, and rest period between biosamples. However, volume recommendations for daily phlebotomies are lacking. We examined the effect of daily blood draws in the rhesus macaque over a 15-day period to determine whether serial blood draws under the conditions of a concurrent flavivirus study could be performed safely without impacting their health or well-being. To do this we examined the change in packed cell volume from day 1 to day 15 from a centrifuged tail prick blood sample to determine whether or not the animals became anemic and the degree of anemia. We performed a retrospective comparison of the packed cell volume and complete blood count hematocrit. Finally, we evaluated weight change during the serial blood draws and examined our blood collection methods to identify areas to refine future studies incorporating serial phlebotomy in the experimental design. Although the number of macaques outside of the hematocrit reference range was statistically significant, the anemia was mild. Based on the degree of anemia, absolute change in PCV, clinical signs, and recovery displayed by day 28, we determined that daily blood collection was safe for the macaques’ health and welfare while warranting increased monitoring in studies that require daily phlebotomy. In addition, PCV and HCT were significantly different with a positive correlation, a clinically inapparent but statistically significant weight loss was identified, and total blood volume collected was higher than targeted volume.