cloprostenol and deslorelin

This study investigated the reproductive effects in Holstein-Friesian cows of once or twice weekly intramuscular injection for 6 weeks of 100 microg of the GnRH agonist deslorelin at intervals. Oestrus was synchronized in non-lactating Holstein-Friesian cows before they were allocated randomly to receive either 100 microg deslorelin once weekly (D1; N=10) or twice weekly (D2; N=8) or acted as untreated controls (CON; N=8). The first injection was given on day 6 post-oestrus and the last injection on day 48 post-oestrus. Blood samples were collected twice weekly from each cow until day 76 after the synchronized oestrus to profile plasma P4. A single injection of prostaglandin was administered to all cows on day 20 post-oestrus to ensure luteolysis occurred. Ovaries were examined twice weekly by transrectal ultrasonography and then subsequently at weekly intervals to monitor ovarian structures. Progesterone profiles observed over two complete cycles for CON cows were typical of those expected for cows displaying regular oestrous cycles. Injection of deslorelin on day 6 post-oestrus induced ovulation in 100% (18/18; D1 and D2) of deslorelin-treated cows. Three categories of responses based on plasma P4 profiles were defined amongst the deslorelin-treated cows. Complete anoestrus was observed in 20% (2/10) of D1 and 63% (5/8) of D2 cows. A partial response characterised by intermittently low concentrations of P4 was observed in 50% (5/10) of D1 and 25% (2/8) of D2. A complete lack of response to deslorelin, with P4 profiles indistinguishable from CON cows, was seen in 30% (3/10) of D1 and 13% (1/8) of D2 cows. When results from D1 and D2 were pooled, a greater proportion of deslorelin-treated cows had abnormal ovarian cycles during the treatment period (56% versus 0%; D1 and D2 versus CON, P <0.001). In conclusion, the repeated injection of deslorelin either once or twice weekly for 6 weeks significantly altered the ovarian cycles of some cows; individual cow responses observed varied widely and ranged from complete anoestrus to a cycle indistinguishable from normal.

Topics: Animals; Cattle; Cloprostenol; Estrous Cycle; Estrus; Estrus Synchronization; Female; Injections, Intramuscular; Ovulation Induction; Progesterone; Reproduction; Time Factors; Triptorelin Pamoate

Follicular diameter is used as a guiding tool to predict ovulation in the mare. However, the great range in preovulatory follicular diameter makes prediction of optimal breeding time based on follicular diameter unreliable. Uterine edema pattern is also useful to determine the best time to breed, since intensity of edema tends to dissipate as ovulation approaches, however, not every mare follows this pattern. The aims of this study were to assess the repeatability of preovulatory follicular diameter and uterine edema pattern in two consecutive spontaneous cycles and to determine how induction treatments (hCG, PGF(2)alpha and GnRH analogues) influence them. Fifty-three mares were followed during two consecutive cycles and scanned three times a day from 2 to 3 days before ovulation. During the first cycle, mares had a spontaneous ovulation and in the consecutive cycle mares received either: (a) no hormonal treatment; (b) 1500 IU hCG; (c) 125-250 microg Cloprostenol or (d) 2.1 mg Deslorelin implant. Mares ovulated consistently from similar follicular diameters in two consecutive spontaneous cycles (r=0.89; P<0.000). All three induction treatments had a significant effect on reducing the preovulatory follicular diameter (P<0.005). Mares showed fair correlation in uterine edema patterns in both consecutive non-induced cycles (r=0.71; P<0.005). In conclusion mares in consecutive cycles ovulated from consistent follicular diameters. Follicular diameters recorded from previous ovulations can be relied on to predict the optimal breeding time in successive cycles especially in mares that ovulate from unusually small follicles.

Topics: Animals; Chorionic Gonadotropin; Cloprostenol; Estrous Cycle; Female; Horses; Ovarian Follicle; Ovulation Induction; Triptorelin Pamoate; Ultrasonography; Uterus

Practical estrus synchronization schemes are needed for mares. The Ovsynch synchronization protocol for cattle involves the administration of gonadotropin-releasing hormone (GnRH) to induce ovulation or luteinization of dominant follicles during the luteal phase and prostaglandin 7 days later to cause regression of any luteal tissue and development of a preovulatory follicle. An Ovsynch-type synchronization program potentially could be developed for horses if luteinization or ovulation of diestrous follicles occurred in response to GnRH treatment. The objective of this study was to determine if administration of the GnRH agonist, deslorelin acetate, on Day 8 or 12 postovulation would induce luteinization or ovulation of diestrous follicles in the mare. The model used was cycling mares maintained in an artificial luteal phase by administration of a synthetic progestin following prostaglandin-induced luteal regression. On the day of ovulation, 21 light horse mares were randomly assigned to one of three groups: (1) no GnRH, altrenogest from Days 5 to 15 postovulation with prostaglandin on Day 15; (2) GnRH on Day 8, altrenogest from Days 5 to 15 with prostaglandin given on Day 6 to induce luteolysis of the primary corpus luteum, an implant containing 2.1mg of deslorelin acetate inserted on Day 8 and removed on Day 10, with a second prostaglandin treatment on Day 15; (3) GnRH on Day 12, altrenogest from Days 9 to 19, prostaglandin on Day 10, a deslorelin acetate implant injected on Day 12 (subsequently removed on Day 14), and a second dose of prostaglandin administered on Day 19. Follicular development was monitored every other day from Day 5 until a 30-mm sized follicle was observed, and then daily to detection of ovulation. Serum progesterone concentrations were determined daily for 12 consecutive days. Progesterone concentrations in Group 1 remained elevated until approximately Day 12 postovulation. Prostaglandin administration on Day 15 resulted in complete luteolysis in all seven mares. In Group 2, progesterone concentrations in six of seven mares declined to baseline after prostaglandin treatment. No increase in serum progesterone was noted in any of the six mares that were given GnRH on Day 8, including three mares that had diestrous follicles > or =30mm in diameter at the time of treatment. Similarly, progesterone concentrations in six of seven mares in Group 3 declined to baseline after prostaglandin and there was no increase in progesterone after adm

Topics: Animals; Cloprostenol; Diestrus; Drug Implants; Estrus Synchronization; Female; Gonadotropin-Releasing Hormone; Horses; Luteinization; Luteolysis; Ovarian Follicle; Ovulation; Progesterone; Trenbolone Acetate; Triptorelin Pamoate

Deslorelin implants, approved for use in inducing ovulation in mares, have been associated with prolonged interovulatory intervals in some mares. Administration of prostaglandins in the diestrous period, following a deslorelin-induced ovulation, has been reported to increase the incidence of delayed ovulations. The goals of the present study were: (1) to determine the percentage of mares given deslorelin that experience delayed ovulations with or without subsequent prostaglandin treatment, and (2) to determine if removal of the implant 48 h after administration would effect the interval to subsequent ovulation. We considered interovulatory intervals to be prolonged if they were greater than the mean +/- 2 standard deviation (S.D.) of the control group in study 1 and the hCG group in study 2. In study 1, we retrospectively reviewed reproduction records for 278 mares. We either allowed the mare to ovulate spontaneously or induced ovulation using deslorelin acetate implants or hCG. We administered prostaglandin intramuscularly, 5-9 days after ovulation in selected mares in each group. A higher percentage of mares which were induced to ovulate with deslorelin and given prostaglandins had a prolonged interovulatory interval (23.5%; n = 16), as compared to deslorelin-treated mares that did not receive prostaglandins (11.1%; n = 5). In study 2, we induced ovulation in mares with hCG (n = 47), a subcutaneous deslorelin implant via an implanting device provided by the manufacturer (n = 28), or a deslorelin implant via an incision in the neck (n = 43) and we removed the implant 48 h after administration. We administered prostaglandin to all mares 5-9 days after ovulation. In study 2, mares from which the implant was removed had a normal ovulation rate and none had a prolonged interval to ovulation. Administration of prostaglandin after deslorelin treatment was associated with a longer interval from luteolysis to ovulation than that found in mares not treated with deslorelin. Prostaglandin administration during diestrus may have exacerbated the increased interval to ovulation in deslorelin-treated mares. We hypothesize that prolonged secretion of deslorelin from the implant was responsible for the extended interovulatory intervals.

Topics: Animals; Chorionic Gonadotropin; Cloprostenol; Drug Implants; Female; Gonadotropin-Releasing Hormone; Horses; Humans; Ovulation; Ovulation Induction; Retrospective Studies; Time Factors; Triptorelin Pamoate