When the penis is relaxed and inside the sheath, there are many folds of skin along the interior where dirt and smegma collect straw or plant material may collect, too. A stallion has an erection often several times a day even without the stimulation of a mare, year round. When this happens, all the folds in the interior of the sheath are pulled tight, dislodging any trapped material. A gelding is a different story. Most never have erections or fully extrude their penis and the smegma collects inside the sheath.
Is it really necessary? Maybe not. The goal of cleaning is to lower any risk of irritation and infection by removing the waxy secretions, called smegma, that collect in this sensitive region. But frequent cleaning, it turns out, actually fosters an increase in bacteria and gunky secretions in the sheath.
Condom , contraceptive and prophylactic device consisting of a sheath that fits over the penis or inside the vagina and that is intended to prevent the entry of semen into the vagina and to protect against the exchange of sexually transmitted diseases acquired through various means of sexual contact. It is made of very thin, flexible rubber or a rubberlike plastic latex. The condom has long been used as protection against venereal infections and other sexually transmitted diseases, and by the 17th century it was utilized as a contraceptive as well. Early condoms were generally made of animal gut or fish membrane and were often inefficient. Legend is confused on the origin of the term condom —one story tells of a man named Condom devising such a contraceptive for Charles II of England.