Abstract

The hemodilution effect of manually pre-heparinized syringes was determined by evaluation of packed cell volume (PCV) and total solids (TS) from blood samples collected from 50 American alligators (Alligator mississippiensis). A volume of 0.2 ml of blood was drawn into each of three 1-ml syringes: control with no heparin, heparin drawn to 0.1 ml then expelled, and heparin drawn to 0.2 ml then expelled. The order of blood collection into each syringe was randomized and the investigators were blinded to the heparin content of each syringe. PCV and TS values were determined from each syringe immediately after collection. Mean PCV and TS were compared between the control and heparin groups using linear mixed modeling. The syringes coated with heparin resulted in a significantly lower mean PCV and TS compared to controls, with no significant difference between the heparin groups (p<0.001). This dilution effect was also found to be inconsistent and not accurate from one syringe to another. An adjunct method of collecting 0.5 ml of blood into 1-ml syringes coated with heparin drawn to 0.2 ml then expelled also showed a significant decrease in PCV and TS when compared to the control samples, although to a lesser extent (p<0.001). As a result, it cannot be recommended to manually heparinize syringes prior to collection of small blood samples from reptiles because significant and unpredictable hemodilution is likely to occur.