Menstruation (mammal)
Menstruation in mammals is the shedding of the uterine lining (endometrium). It occurs on a regular basis in uninseminated sexually reproductive-age females of certain mammal species.
Animal sexual behaviour
There is nothing in female mammals' anatomy or physiology that contradicts that stimulation of the sexual organs and mating is able to be a positive experience. For instance, the clitoris acts in the same way as with women, and scientific studies have shown that the success of reproduction is improved by stimulation of clitoris on (among other species) cows and mares in connection with insemination, because it improves the transportation of the sperm due to contractions of the inner genitalia. This probably also applies to female animals of other animal species, and contractions in the inner genitals are seen e.g. also during orgasm for women. It is therefore reasonable to assume that sexual intercourse may be linked with a positive experience for female animals.
Koinophilia is the love of the "normal" or phenotypically common (from the Greek, "koinos", meaning "the usual" or "common"). The term was introduced to scientific literature in 1990, and refers to the tendency of animals seeking a mate to prefer that mate not to have any unusual, peculiar or deviant features. Similarly, animals preferentially choose mates with low fluctuating asymmetry.