Filliettaz, C., Maxwell, L., Dragon, M. et al. 2020. Novel bleeding techniques in hamsters. Laboratory Animal Science Professional 8(1) (January/February), 44-46.

Hamsters have historically been used in our pharmacokinetic (PK) studies using the retro-orbital (RO) bleeding technique to collect blood samples. If performed incorrectly, this technique has the potential for animal welfare complications not usually seen with other phlebotomy methods. Our Institutional Animal Care and Use Committee does not approve RO blood collection as a routine procedure given the potential for permanent, irreversible damage caused by repetitive sampling, and limits RO collection to one per eye over the life of the animal. Because of this limitation, more animals were used, and the blood samples were composite samples from multiple animals. To refine hamster PK studies, we identified a method that allowed for serial blood collection over multiple time points from the same animal with minimal tissue damage. The objective was to reduce the number of animals needed for a PK study and increase data quality as a result of using the same animal throughout the study. In this study, we explored the possibility of collecting blood from the tail of the hamster via tail nick as compared to blood collection from jugular vein, saphenous vein, and RO methods. While jugular and saphenous vein techniques have been described in hamsters, tail nick is an innovative, unpublished technique we developed and refined. Forty purpose-bred male Syrian Hamsters were used to collect blood and divided into 4 groups: jugular vein, saphenous vein, tail nick, and RO groups. Based on this study, the tail nick blood collection method appeared to be a viable alternative to the commonly used RO blood collection technique for PK studies in hamster and was superior to jugular vein and saphenous vein methods. The novel tail nick blood collection method was the only alternative method to RO, which provided the required 7 samples consistently without any impact on animals. Blood collection via the saphenous vein was the least successful and resulted in more local tissue trauma. Benefits of this technique included data quality improvements by decreasing the variability associated with composite samples, a significant reduction in the number of animals used, and refinement of a technique not associated with any serious animal welfare concerns.