Fate and turnover rate of ovarian follicular cysts in dairy cattle

Abstract

Non-lactating, multiparous dairy cows diagnosed as having cysts by palpation per rectum were used. Cysts were induced with oestradiol-17 beta (15 mg) and progesterone (37.5 mg) dissolved in ethanol and injected s.c. twice daily for 7 days. Following initial diagnosis of cysts, ovaries were exposed by midventral laparotomy, and the perimeter of the base of each cyst was marked with subepithelial injections of charcoal. Ovaries were removed from cows by transvaginal incision at 10 days (Group 1; N = 8), 20 days (Group 2; N = 8), or 40 days (Group 3; N = 7) after marking of cysts. Ovaries were examined for structures present and their relationship to the marked site. Corpora lutea with ovulation papilla were present in 7/23 cows (1/8, 4/8 and 2/7, for Groups 1, 2 and 3, respectively). In these 7 cows, corpora lutea were at a site different from the original structure that was marked. Marked structures persisted for the duration of the experimental period in 1 and 2 cows, in Groups 1 and 3, respectively. In the remaining 13 cows, new large follicular structures (cysts) were present at a site other than that marked with charcoal. These structures developed on the ovary contralateral to the one originally marked in 9 of 13 cows. Cysts are therefore dynamic in nature and may persist or may be replaced by others.

Follicular cysts occur after a normal estradiol-induced GnRH/LH surge if the corpus hemorrhagicum is removed

“…Numerous previous studies have hormonally induced cows to have follicular cysts, using large doses of exogenous E 2 . About 50% of cows became anovular following these treatments (Cook et al 1990, Hamilton et al 1995, Calder et al 1999. Cows with induced follicular cysts appear to be in a physiological state in which high circulating E 2 either produces a delayed However, this is the first study, to our knowledge, that has shown that this lack of hypothalamic responsiveness to E 2 and follicular cysts can be induced by the normal increase in E 2 simply by preventing the post-ovulatory rise in circulating P 4 .…”

“…Development of an appropriate model is essential for studies on the underlying physiology of follicular cysts. Several different methods have been used to induce animals into an anovular condition resembling follicular cysts including estradiol (E 2 ) treatment during diestrus (Wiltbank et al 1961, Nadaraja & Hansel 1976, multiple treatments with high doses of progesterone (P 4 ) and E 2 (Erb et al 1973, Cook et al 1990, Hamilton et al 1995, Calder et al 1999 and prolonged E 2 exposure (Dobson et al 1996(Dobson et al , Ö zturk et al 1998. Follicular cysts can also be induced with a single E 2 injection if E 2 is given at a time when the gonadotropin-releasing hormone (GnRH)/luteinizing hormone (LH) surge will occur in the absence of a potentially ovulatory follicle .…”

Treatment of cystic ovarian disease in dairy cows with gonadotrophin‐releasing hormone: A field study

“…Interval between 1st treatment and 1st insemination. 3. Interval between 1st insemination after the 1st treatment and conception.…”

“…Roberts (20) defined COD as the persistence of an anovulatory follicular structure (> 2.5 cm) in the absence of luteal tissue, and Cook et al (3) defined COD as the presence of non-ovulatory follicles larger than 2.0 cm for at least 10 days without development of a corpus luteum. However, Farin (10) noted that cysts sometimes occur simultaneously with a corpus luteum.…”

Changes of Ovarian Structures, Plasma LH, FSH, Progesterone and Estradiol-17.BETA. in a Cow with Ovarian Cysts Showing Spontaneous Recovery and Relapse.

“…This ovarian disorder is one of the most important causes of infertility in cattle, and is attended with considerable economic loss because of its high incidence [11]. Cook et al [4] reported that steroid-induced follicular cysts in cattle were not static structures, but regressed to be replaced with other cystic structures. Furthermore, previous investigations [7,17] showed that spontaneously occurring ovarian cysts also exhibit a turnover of cysts, and suggested that the absence of a preovulatory surge of luteinizing hormone (LH) causes ovarian cysts [3,7,17].…”