Acute cortisol responses and wound healing in lambs after ring castration plus docking with or without application of a castration clamp to the scrotum.
Sutherland MA, Stafford KJ, Mellor DJ, Gregory NG, Bruce RA, Ward RN, Aust Vet J, 2000 Jun - link

Acute cortisol responses of lambs to ring castration and docking after the injection of lignocaine into the scrotal neck or testes at the time of ring application.
Sutherland MA, Mellor DJ, Stafford KJ, Gregory NG, Bruce RA, Ward RN, Todd SE, Aust Vet J, 1999 Nov - link