Using the Artificial Vagina.
It is necessary to apply pressure to the spiraled glans penis so that it locks at complete erection as in the cervical folds of the sow. This can be achieved with a heavy rubber casing 4.5 cm in diameter and 12.5 cm long with a rubber liner and a small piece of sponge rubber between it and the casing where warm water at 45 to 50 degrees Celsius is placed to warm the artificial vagina. The sponge rubber causes increased pressure on the glans penis.
Larsen RE (1981)