Physiological and pathological impact of blood sampling by retro-bulbar sinus puncture and facial vein phlebotomy in laboratory mice.

Retro-bulbar sinus puncture and facial vein phlebotomy are two widely used methods for blood sampling in laboratory mice. However, the animal welfare implications associated with these techniques are currently debated, and the possible physiological and pathological implications of blood sampling using these methods have been sparsely investigated. Therefore, this study was conducted to assess and compare the impacts of blood sampling by retro-bulbar sinus puncture and facial vein phlebotomy. Blood was obtained from either the retro-bulbar sinus or the facial vein from male C57BL/6J mice at two time points, and the samples were analyzed for plasma corticosterone. Body weights were measured at the day of blood sampling and the day after blood sampling, and the food consumption was recorded automatically during the 24 hours post-procedure. At the end of study, cheeks and orbital regions were collected for histopathological analysis to assess the degree of tissue trauma. Mice subjected to facial vein phlebotomy had significantly elevated plasma corticosterone levels at both time points in contrast to mice subjected to retro-bulbar sinus puncture, which did not. Both groups of sampled mice lost weight following blood sampling, but the body weight loss was higher in mice subjected to facial vein phlebotomy. The food consumption was not significantly different between the two groups. At gross necropsy, subcutaneous hematomas were found in both groups and the histopathological analyses revealed extensive tissue trauma after both facial vein phlebotomy and retro-bulbar sinus puncture. This study demonstrates that both blood sampling methods have a considerable impact on the animals' physiological condition, which should be considered whenever blood samples are obtained.

Comparison of silicone and polyurethane catheters for the catheterization of small vessels in mice.

Vascular catheterization is increasingly carried out in laboratory mice, but the long-term patency of catheters implanted in mice is limited owing to their small size. The authors compared mice that were catheterized in their right common carotid artery either with a silicone catheter with a polyurethane tip or with a 100% polyurethane catheter to determine which catheter type was better suited for long-term studies in mice. The catheters were inspected daily and were flushed if blood was visible in the catheters; if no blood was visible, they were flushed every 3 d. Silicone catheters were patent for a shorter period of time than polyurethane catheters, which were patent for a median of 6 d and up to 25 d. The authors identify the principal causes of catheter failure and discuss how they can be prevented.