Erection - in Non-human Animals

In Non-human Animals

At the time of penetration, the canine penis is not erect, and only able to penetrate the female because it includes a narrow bone called the baculum, a feature of most placental mammals. After the male achieves penetration, he will often hold the female tighter and thrust faster, and it is during this time that the male's penis expands. Unlike human sexual intercourse, where the male penis commonly becomes erect before entering the female, canine copulation involves the male first penetrating the female, after which swelling of the penis to erection occurs.

An elephant's penis is S-shaped when fully erect and has a Y-shaped orifice.

Given the small amount of erectile tissue in a bull's penis, there is little enlargement after erection. The penis is quite rigid when non-erect, and becomes even more rigid during erection. Protrusion is not affected much by erection, but more by relaxation of the retractor penis muscle and straightening of the sigmoid flexure.

A male fossa's penis reaches to between his forelegs when erect.

When not erect, a horse's penis is housed within the prepuce, 50 centimetres (20 in) long and 2.5 to 6 centimetres (0.98 to 2.4 in) in diameter with the distal end 15 to 20 centimetres (5.9 to 7.9 in). The retractor muscle contracts to retract the penis into the sheath and relaxes to allow the penis to extend from the sheath. When erect, the penis doubles in length and thickness and the glans increases by 3 to 4 times. Erection and protrusion take place gradually, by the increasing tumescence of the erectile vascular tissue in the corpus cavernosum penis. Most stallions achieve erection within 2 minutes of contact with an estrus mare, and mount the estrus mare 5-10 seconds afterward.