Automated registration of tail bleeding in rats

Summary

An automated system for registration of tail bleeding in rats using a camera and a user-designed PC-based software program has been developed. The live and processed images are displayed on the screen and are exported together with a text file for later statistical processing of the data allowing calculation of e.g. number of bleeding episodes, bleeding times and bleeding areas. Proof-of-principle was achieved when the camera captured the blood stream after infusion of rat whole blood into saline. Suitability was assessed by recording of bleeding profiles in heparintreated rats, demonstrating that the system was able to capture on/off bleedings and that the data transfer and analysis were conducted successfully. Then, bleeding profiles were visually recorded by two independent observers simultaneously with the automated recordings after tail transection in untreated rats. Linear relationships were found in the number of bleedings, demonstrating, however, a statistically significant difference in the recording of bleeding episodes between observers. Also, the bleeding time was longer for visual compared to automated recording. No correlation was found between blood loss and bleeding time in untreated rats, but in heparinized rats a correlation was suggested. Finally, the blood loss correlated with the automated recording of bleeding area. In conclusion, the automated system has proven suitable for replacing visual recordings of tail bleedings in rats. Inter-observer differences can be eliminated, monotonous repetitive work avoided, and a higher through-put of animals in less time achieved. The automated system will lead to an increased understanding of the nature of bleeding following tail transection in different rodent models.

Keywords

Bleeding time - tail transection - animal model - instrumentation - rats

• References

• 1 Tranholm M, Kristensen K, Kristensen AT. et al. Improved hemostasis with superactive analogs of factor VIIa in a mouse model of hemophilia A. Blood 2003; 102: 3615-3620.
• 2 Dejana E, Callioni A, Quintana A. et al. Bleeding time in laboratory animals. II – A comparison of different assay conditions in rats. Thromb Res 1979; 15: 191-197.
• 3 Stella L, Donati MB, de Gaetano G. Bleeding time in laboratory animals I. Aspirin does not prolong bleeding time in rats. Thromb Res 1975; 7: 709-716.
• 4 Lavelle SM, MacIomhair M. Bleeding times and the antithrombotic effects of high-dose aspirin, hirudin and heparins in the rat. Ir J Med Sci 1998; 167: 216-220.
• 5 Pawlinski R, Pedersen B, Erlich J. et al. Role of tissue factor in haemostasis, thrombosis, angiogenesis and inflammation: lessons from low tissue factor mice. Thromb Haemost 2004; 92: 444-450.
• 6 Dejana E, Villa S, de Gaetano G. Bleeding time in rats: a comparison of different experimental conditions. Thromb Haemost 1982; 48: 108-111.
• 7 Elg M, Carlsson S, Gustafsson D. Effects of agents, used to treat bleeding disorders, on bleeding time prolonged by a very high dose of a direct thrombin inhibitor in anesthesized rats and rabbits. Thromb Res 2001; 101: 159-170.
• 8 Tamai Y, Takami H, Nakahata R. et al. Development and practical use of the new quantitative bleeding time test apparatus. Thromb Haemost 1998; 80: 181-185.