Dog's Isolated Hind Limb Preparation as a Suitable Method for the Study of Hemostasis

¹ From the Laboratory of Haematology, Instituto Oswaldo Cruz, Rio de Janeiro, Brasil

A method of studying hemostasis in vivo, employing the well-known dog's hind limb preparation, used by physiologists for the study of the vasomotor properties of the circulatory system of this region, is presented here in detail. Using noncoagulable blood and controlling the flow of blood through the preparation, normal hemostasis of 8.5 minutes on the average is obtained, if certain conditions are observed. The importance of innervation for the maintenance of normal hemostasis is confirmed, since cutting of the femoral nerve or death of the animal causes the blood to become nonhemostatic. Under certain conditions this preparation may function for 6 hours or more, although some blood samples lose hemostatic power spontaneously after 2 hours. The resistance of the hemostatic property of blood samples to violent centrifugation and later resuspension diminishes in the course of time when it remains at laboratory temperature. The coagulation function in the bleeding time of small blood vessels and capillaries seems to be limited to a mere accelerating effect (bleeding time 40% less than that obtained with noncoagulable blood). When the preparation is irrigated by a blood sample without hemostatic power indicated by a bleeding time greater than 30 minutes, it almost always loses its usefulness as a method of indicating hemostatic capacity, since any hemostatic sample (normal arterial blood) is met within blood vessels and capillaries incapable of demonstrating it.