Reproductive physiology of the female cat

Abstract: The cat is one of our most common pets. Understanding the reproductive physiology of the queen is important, not only for the knowledge of our domestic cats but also for wild undomesticated feline species, many of which have been reported endangered. Understanding the mechanisms behind the estrous cycle, ovulation and pregnancy is also important for handling the feral cat populations that are a problem in several countries. The purpose of this literature study is to look into the hormonal patterns of the reproductive physiology of the female cat, with focus on ovulation, pregnancy and pseudo-pregnancy, and from this information determine in which fields more research would be needed. The female cat is seasonally polyestrous in Sweden, meaning that she can have several estrous cycles during the breeding season but goes through a long period of reproductive dormancy during the darker months of the year. The queen is considered an induced ovulator, with copulation triggering the release of luteinizing hormone (LH) from the pituitary gland needed for ovulation. However, it has been seen that many queens are capable of spontaneous ovulation in the presence of a tomcat or other female cats in estrus. The estrous cycle in the cat consists of several behavioral phases, defined differently by different authors. In this study, the estrous cycle will be described as consisting of five phases: proestrus, estrus, interestrus, diestrus and anestrus. The induced ovulation in the queen has been shown to be dependent on several factors: the number of matings and the intervals between them, the day of estrus she was mated and individual differences in the LH peak she was able to produce. If the queen ovulates but do not conceive, she will enter into a pseudo-pregnant phase that is similar to pregnancy for the first 40 days. After 40 days, the plasma levels of progesterone produced by the corpora lutea will be back at almost basal level in the pseudo-pregnant cat, due to luteal regression. If the queen is mated and become pregnant, she will go through a longer progesterone dominated phase than during pseudo-pregnancy. Whether the placenta in the cat is responsible for producing the progesterone that maintains pregnancy after the luteal regression has begun is still unclear. It can be concluded that the reproductive processes of the female cat are not completely mapped out. More research is needed on some subjects, such as the mechanisms of the induced ovulation and the hormonal role of the placenta during pregnancy, for a more complete understanding of the reproductive physiology of the queen.