Ovarian Follicular Cysts in Dairy Cows

Abstract

Ovarian follicular cysts are anovulatory follicular structures that occur in 10 to 13% of dairy cows. This review focuses upon the dynamics of cyst growth, development, and persistence as well as on associated endocrine and cellular mechanisms. During the estrous cycle of cows, two to four waves of follicular growth occur. From a cohort of recruited follicles, one is selected for continued growth and dominance while the other undergo atresia and regress. In contrast, cysts have long been thought to be static structures that persist for extended periods. Although cysts can persist for extended periods, most regress over time and are replaced during subsequent follicular waves. The next dominant follicle either ovulates or develops into a new cyst. The recruitment of a cohort of follicles from which a cyst develops and the growth rate of cysts to ovulatory size are similar to ovulatory follicular waves, but the cyst continues to grow for a longer period. The interval between waves of follicular growth is longer for cows with cysts than for cows with normal estrous cycles. Each wave is preceded by a transient increase in circulating FSH. Near the time of cyst development and persistence, the concentration of FSH is not different from that during normal estrous cycles. Serum concentrations of LH and estradiol-17 beta are higher in cows that develop cysts than in cows that do not. Conversely, hypothalamic content of GnRH is lower in cows with cysts. Thus, cysts are dynamic structures, and their development and lifespan are likely associated with altered hypothalamic-hypophysial-ovarian function.

Risk factors associated with detailed reproductive phenotypes in dairy and beef cows

“…The increase in the prevalence of cystic structures may be related to the increased milk production observed over the same period (Horan et al, 2006). The occurrence of follicular cysts has been previously identified to have greater incidences and occur earlier postpartum compared with luteal cysts (Garverick, 1997). The presence of cystic structure in early lactation that persisted throughout the remainder of the lactation may be related to the combination of both types of cystic structures into one trait in the present study.…”

“…This is consistent with results in the present study where cows in beef herds in the present study were less likely to be cycling at the time of examination. The occurrence of cystic structures has been most commonly identified in dairy cows (Garverick, 1997;Peter, 2004), with lower incidences reported in beef cows (Peter, 2004). The lower incidence of cystic structures in cows from beef herds may relate to their lower milk production compared with cows in dairy herds The improved uterine score in beef cows is likely related to superior postpartum energy status compared with dairy cows; differences are also likely attributable to differing breeding policies (i.e., selection for increased milk production in dairy cows and increased carcass yield in beef).…”

Post-treatment sequential ultrasound imaging of follicular cyst in a crossbred dairy cow

“…Different responses of follicular cysts to the treatment have been reported including partial or complete luteinization, regression, and ovulation [4,7]. In this case, after hCG treatment the follicular cyst showed a consistent regression to a very small anechoic area on day 7 (Figs.…”

“…The condition has a huge negative impact on fertility and overall productivity, owing to its effects on reproductive parameters such as calving to conception interval, number of services per conception, and pregnancy rate [2,3]. Incidence has been reported to vary from 5.6 to 18.8 % [4], although the actual figure may be higher because of the fact that 60 % of cows that develop cystic ovarian degeneration before the first postpartum ovulation recover spontaneously and may go undetected [5]. Diagnosis is generally made on the basis of behavioral abnormalities, transrectal examination, ultrasonography (USG), and plasma or milk progesterone assays.…”

Follicle-stimulating hormone isoforms and plasma concentrations of estradiol and inhibin A in dairy cows with ovulatory and non-ovulatory follicles during the first postpartum follicle wave

“…The first postpartum dominant follicle ovulates, becomes atretic, or develops into a cyst, with approximate 25 frequencies of 40, 40 and 20%, respectively (2). This has a major impact on the duration of postpartum anestrus, as atretic and cystic follicles are likely to be replaced by follicles with similar fates (2,3). A prompt resumption of ovulatory activity following parturition is desirable; cows that have an early commencement of luteal activity have an improved likelihood of conception after breeding (4).…”