Safety and blood sample volume and quality of a refined retro-orbital bleeding technique in rats using a lateral approach.

The collection of blood samples from laboratory rats requires the use of bleeding techniques that provide quality samples of sufficient volume for analysis without injury to the animal. Retro-orbital bleeding (ROB) is a phlebotomy technique that can yield high-quality samples of adequate volume, but it has been criticized for its potential to cause injury. To evaluate the injury-causing potential of their refined ROB method using a lateral approach, the authors retrospectively reviewed ROB procedures carried out in their colony during an 18-month period and found that 0.6% of these procedures were associated with ocular injury. The authors also compared the quality of blood samples collected by ROB and by saphenous phlebotomy and found that ROB yielded samples of better quality. The authors conclude that, when done using a lateral approach and by an experienced technician, ROB is humane and safe and provides blood samples of adequate volume and quality for analysis.