Subaqueous tail bleeding time in rodents

The damage of a blood vessel results in the formation of a hemostatic plug, which is achieved by several differ-entmechanisms including vascular spasm, formation of a platelet plug, blood coagulation, and growth of fibrous tissue into the blood clot. 

A diagnostic parameter for specific defects of the hemostatic system and for the influence of drugs affecting hemostasis is the length of time that it takes for bleeding to stop from a standard incision, the so-called bleeding time. 

Bleeding-time measurements in animals are used to evaluate the hemorrhagic properties of antithrombotic drugs. The transection of the tail of a rodent was first established by Dottl and Ripke (1936) and is commonly used in experimental pharmacology. 

Anaesthetized rats are fixed in supine position on a temperature-controlled (37 °C) heating-table. Following catheterization of a carotid artery (for measurement of blood pressure) and a jugular vein, the test compound is administered. After a defined latency period, the tail of the rat is transected with a razor-blade mounted on a self-constructed device at a distance of 4 mm from the tip of the tail. Immediately after transection, the tail is immersed into a bath filled with isotonic saline solution (37 °C). 

The time until bleeding stops is determined within a maximum observation time of 600 s. 

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