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Catherine A Herbert - One of the best experts on this subject based on the ideXlab platform.
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effects of Deslorelin implants on reproduction and feeding behavior in tasmanian devils sarcophilus harrisii housed in free range enclosures
Theriogenology, 2018Co-Authors: Holly R Cope, Carolyn J Hogg, Karen Fagg, Olivia Barnard, Peter White, Catherine A HerbertAbstract:Abstract In captive breeding programs, it is becoming increasingly important to maximize the retention of genetic diversity by managing the reproductive contribution of each individual, which can be facilitated through the use of selective contraception. This becomes critical when captive populations are held for several generations, and managers must prevent the confines of housing space and financial support from compromising genetic integrity. For example, the Tasmanian devil insurance population, established in 2006, is strategically managed to equalize founder representation. This becomes difficult when devils are housed in large groups in free-range enclosures (FREs). This study examined the efficacy, duration and potential side effects of Suprelorin® contraceptive implants (containing 4.7 mg of Deslorelin) on Tasmanian devils housed in FREs. Females were monitored to assess post-treatment reproductive rates, feeding behavior and weight changes. Suprelorin® successfully prevented reproduction in all treated females (P 0.05) and there was no effect of contraception on order of arrival at food (P = 0.632), suggesting no alterations to social structure. Devils with pouch young spent more time feeding than those without (P
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effects of Deslorelin implants on reproduction in the common brushtail possum trichosurus vulpecula
Reproduction Fertility and Development, 2007Co-Authors: Jutta Eymann, Catherine A Herbert, D. W. Cooper, T E Trigg, Douglas C Eckery, Brian P ThomsonAbstract:The present study investigated the effects of slow-release implants containing the gonadotrophin-releasing hormone (GnRH) agonist Deslorelin on reproduction in the common brushtail possum (Trichosurus vulpecula). Captive female brushtail possums were assigned to control (placebo implant), low dose (4.7 mg Deslorelin) or high dose (9.4 mg Deslorelin) groups; males were assigned to control or high dose (9.4 mg Deslorelin) groups. The acute effects of Deslorelin treatment at the level of the pituitary gland were similar between the two sexes, where a transient rise in luteinising hormone concentration was induced over the first 24 h. In females, this was associated with the disruption of the normal oestrous cycle and mating within 2-10 days in some treated individuals, but no young were subsequently detected. By 3 weeks after treatment, treated females became anoestrus and remained infertile for at least one breeding season. The effects of treatment were reversible in a subset of females that had their implants removed, although the time taken to produce offspring was variable. Paradoxically, male brushtail possums remained fertile during chronic Deslorelin exposure. Despite significant declines in basal follicle-stimulating hormone and testosterone concentrations, as well as an inability to respond to a GnRH challenge, treated males sired as many offspring as control males and there was no evidence of testicular regression. In conclusion, there is potential to control reproduction in female brushtail possums by using chronic GnRH agonist treatment.
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fertility control in female eastern grey kangaroos using the gnrh agonist Deslorelin 2 effects on behaviour
Wildlife Research, 2006Co-Authors: R Woodward, Marie E Herberstein, Catherine A HerbertAbstract:In recent years fertility control has been proposed as an ethically acceptable alternative to lethal control techniques when managing overabundant kangaroo populations. A promising non-steroidal, non-immunological approach to contraception in female kangaroos involves the use of slow-release implants containing the gonadotrophin-releasing hormone (GnRH) agonist Deslorelin. The practicality of using Deslorelin implants as a management option is dependant on its effective inhibition of reproduction without negative physical or behavioural side-effects. This study investigated the behavioural effects of Deslorelin implants in female eastern grey kangaroos. Treatment had no detectable effects on crepuscular activity. Alterations in the frequency of sexual interactions were observed in Deslorelin-treated females, with a behavioural oestrus induced ~3 days after combined removal of pouch young and Deslorelin administration. Copulation was observed during this early oestrous period, but conception was not achieved and pouch young were not observed in any treated females. Control females gave birth within 69.6 ± 10.4 days (mean ± s.e.m., n = 9) of placebo implant administration. The first births observed in treated animals were on Days 510, 637 and 643 after treatment. The remaining seven treated animals had not bred by the end of the study, a period of 647 days.
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fertility control in female eastern grey kangaroos using the gnrh agonist Deslorelin 2 effects on behaviour
Wildlife Research, 2006Co-Authors: R Woodward, Marie E Herberstein, Catherine A HerbertAbstract:Eastern grey kangaroos are widespread on the east coast of Australia and frequently reach high densities in reserves and parkland near urban areas. Management of these populations is highly contentious and non-lethal fertility-control technologies are sought as an alternative option to manage population size. This study evaluated the potential of slow-release gonadotrophin-releasing hormone agonist (Deslorelin) implants to inhibit reproduction in female kangaroos. Deslorelin treatment effectively inhibited reproduction in adult females for periods of 559 ± 111 days (n = 6) and 651 ± 21 days (n = 5) after administration of one or two 10-mg implants respectively. Animals treated with the lower dosage tended to resume breeding earlier than those that received a total of 20 mg of Deslorelin (minimum duration of 18 months). Deslorelin treatment had no effect on blastocyst reactivation in a single treated female and repeat treatment had no negative side-effects. This study has demonstrated that slow-release Deslorelin implants can successfully inhibit reproduction for extended periods in the female eastern grey kangaroos. This approach may have potential application in reproductive management of problem kangaroo populations.
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long term effects of Deslorelin implants on reproduction in the female tammar wallaby macropus eugenii
Reproduction, 2005Co-Authors: Catherine A Herbert, Geoff Shaw, T E Trigg, Douglas C Eckery, D. W. CooperAbstract:The contraceptive and endocrine effects of long-term treatment with implants containing the GnRH agonist Deslorelin were investigated in female tammar wallabies (Macropus eugenii). Fertility was successfully inhibited for 515 +/- 87 days after treatment with a 5 mg Deslorelin implant (n = 7), while control animals gave birth to their first young 159 +/- 47 days after placebo implant administration (n = 8). The duration of contraception was highly variable, ranging from 344 to 761 days. The strict reproductive seasonality in the tammar wallaby was maintained once the implant had expired. This inhibition of reproduction was associated with a significant reduction in basal LH concentrations and a cessation of oestrous cycles, as evidenced by low progesterone concentrations. There was evidence to suggest that some aspect of either blastocyst survival, luteal reactivation, pregnancy or birth may be affected by Deslorelin treatment in some animals. These results show that long-term inhibition of fertility in the female tammar wallaby is possible using slow-release Deslorelin implants. The effects of Deslorelin treatment were fully reversible and there was no evidence of negative side effects. Slow-release GnRH agonist implants may represent a practicable method for reproductive management of captive and semi-wild populations of marsupials.
D. W. Cooper - One of the best experts on this subject based on the ideXlab platform.
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effects of Deslorelin implants on reproduction in the common brushtail possum trichosurus vulpecula
Reproduction Fertility and Development, 2007Co-Authors: Jutta Eymann, Catherine A Herbert, D. W. Cooper, T E Trigg, Douglas C Eckery, Brian P ThomsonAbstract:The present study investigated the effects of slow-release implants containing the gonadotrophin-releasing hormone (GnRH) agonist Deslorelin on reproduction in the common brushtail possum (Trichosurus vulpecula). Captive female brushtail possums were assigned to control (placebo implant), low dose (4.7 mg Deslorelin) or high dose (9.4 mg Deslorelin) groups; males were assigned to control or high dose (9.4 mg Deslorelin) groups. The acute effects of Deslorelin treatment at the level of the pituitary gland were similar between the two sexes, where a transient rise in luteinising hormone concentration was induced over the first 24 h. In females, this was associated with the disruption of the normal oestrous cycle and mating within 2-10 days in some treated individuals, but no young were subsequently detected. By 3 weeks after treatment, treated females became anoestrus and remained infertile for at least one breeding season. The effects of treatment were reversible in a subset of females that had their implants removed, although the time taken to produce offspring was variable. Paradoxically, male brushtail possums remained fertile during chronic Deslorelin exposure. Despite significant declines in basal follicle-stimulating hormone and testosterone concentrations, as well as an inability to respond to a GnRH challenge, treated males sired as many offspring as control males and there was no evidence of testicular regression. In conclusion, there is potential to control reproduction in female brushtail possums by using chronic GnRH agonist treatment.
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long term effects of Deslorelin implants on reproduction in the female tammar wallaby macropus eugenii
Reproduction, 2005Co-Authors: Catherine A Herbert, Geoff Shaw, T E Trigg, Douglas C Eckery, D. W. CooperAbstract:The contraceptive and endocrine effects of long-term treatment with implants containing the GnRH agonist Deslorelin were investigated in female tammar wallabies (Macropus eugenii). Fertility was successfully inhibited for 515 +/- 87 days after treatment with a 5 mg Deslorelin implant (n = 7), while control animals gave birth to their first young 159 +/- 47 days after placebo implant administration (n = 8). The duration of contraception was highly variable, ranging from 344 to 761 days. The strict reproductive seasonality in the tammar wallaby was maintained once the implant had expired. This inhibition of reproduction was associated with a significant reduction in basal LH concentrations and a cessation of oestrous cycles, as evidenced by low progesterone concentrations. There was evidence to suggest that some aspect of either blastocyst survival, luteal reactivation, pregnancy or birth may be affected by Deslorelin treatment in some animals. These results show that long-term inhibition of fertility in the female tammar wallaby is possible using slow-release Deslorelin implants. The effects of Deslorelin treatment were fully reversible and there was no evidence of negative side effects. Slow-release GnRH agonist implants may represent a practicable method for reproductive management of captive and semi-wild populations of marsupials.
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effects of a gonadotropin releasing hormone agonist implant on reproduction in a male marsupial macropus eugenii
Biology of Reproduction, 2004Co-Authors: Catherine A Herbert, Geoff Shaw, T E Trigg, Douglas C Eckery, Marilyn B Renfree, D. W. CooperAbstract:This study evaluated the potential of slow-release GnRH agonist (Deslorelin) implants to inhibit reproductive function in the male tammar wallaby. The specific aim was to measure the effects of graded dosages of Deslorelin on testes size and plasma LH and testosterone concentrations. Adult male tammar wallabies were assigned to four groups (n = 6 per group) and received the following treatment: control, placebo implant; low dose, 5 mg Deslorelin; medium dose, 10 mg; high dose, 20 mg. All dosages of Deslorelin induced acute increases (P 0.05). These results suggest that the male tammar wallaby is resistant to the contraceptive effects of chronic GnRH agonist treatment. Despite the maintenance of testosterone secretion, the majority of male tammars (10 of 17) failed to respond to a GnRH challenge with a release of LH between Days 186 and 197 of treatment. The failure of animals to respond to exogenous GnRH suggests a direct effect of Deslorelin on the pituitary, resulting in a level of desensitization that was sufficient to inhibit a LH surge but insufficient to inhibit basal LH secretion. The variation between animals is believed to result from earlier recovery of some individuals, in particular those that received a lower dose, or individual resistance to the desensitization process.
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effects of a gonadotropin releasing hormone agonist implant on reproduction in a male marsupial macropus eugenii
Biology of Reproduction, 2004Co-Authors: Catherine A Herbert, Geoff Shaw, T E Trigg, Douglas C Eckery, Marilyn B Renfree, D. W. CooperAbstract:This study evaluated the potential of slow-release GnRH agonist (Deslorelin) implants to inhibit reproductive function in the male tammar wallaby. The specific aim was to measure the effects of graded dosages of Deslorelin on testes size and plasma LH and testosterone concentrations. Adult male tammar wallabies were assigned to four groups (n 5 6 per group) and received the following treatment: control, placebo implant; low dose, 5 mg Deslorelin; medium dose, 10 mg; high dose, 20 mg. All dosages of Deslorelin induced acute increases (P , 0.001) in plasma LH and testosterone concentrations within 2 h, with concentrations remaining elevated during the first 24 h but returning to pretreatment levels by Day 7. Thereafter, there was no evidence of a treatment-induced decline in plasma testosterone concentrations. There was no detectable difference in basal LH concentrations between treated and control animals, nor was there a significant change in testes width or length (P . 0.05). These results suggest that the male tammar wallaby is resistant to the contraceptive effects of chronic GnRH agonist treatment. Despite the maintenance of testosterone secretion, the majority of male tammars (10 of 17) failed to respond to a GnRH challenge with a release of LH between Days 186 and 197 of treatment. The failure of animals to respond to exogenous GnRH suggests a direct effect of Deslorelin on the pituitary, resulting in a level of desensitization that was sufficient to inhibit a LH surge but insufficient to inhibit basal LH secretion. The variation between animals is believed to result from earlier recovery of some individuals, in particular those that received a lower dose, or individual resistance to the desensitization process.
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effect of Deslorelin implants on follicular development parturition and post partum oestrus in the tammar wallaby macropus eugenii
Reproduction, 2004Co-Authors: Catherine A Herbert, T E Trigg, D. W. CooperAbstract:The effect of treatment with slow release implants containing the GnRH agonist, Deslorelin, was investigated in female tammar wallabies. Pouch young were removed from 16 wallabies presumed to be carrying quiescent blastocysts. Eight received a 5 mg Deslorelin implant and eight received a placebo implant. Animals were caught daily from day 25 to day 30 and their pouches inspected for newborn young and their urogenital sinus checked for a copulatory plug. Treatment with Deslorelin did not affect reactivation of a dormant blastocyst and subsequent birth in 4/8 animals, but post-partum mating was inhibited in these animals. Five control and five treated animals were killed within 0-48 h post partum and their reproductive tracts analysed. At autopsy, all five control animals had large preovulatory follicles but only one Deslorelin-treated animal showed signs of follicular development. These differences were also reflected in the weights of the lateral vaginae, with treated animals showing no evidence of oestrogenic stimulation. The remaining three control and three treated animals were monitored for approximately 2 years. The long-term contraceptive effects of a single 5 mg Deslorelin implant lasted for just under one year. These results indicate that slow release Deslorelin implants inhibit follicular development in the female tammar wallaby for extended periods of time and may have potential application in reproductive management of captive marsupials in the kangaroo family.
Douglas C Eckery - One of the best experts on this subject based on the ideXlab platform.
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effects of Deslorelin implants on reproduction in the common brushtail possum trichosurus vulpecula
Reproduction Fertility and Development, 2007Co-Authors: Jutta Eymann, Catherine A Herbert, D. W. Cooper, T E Trigg, Douglas C Eckery, Brian P ThomsonAbstract:The present study investigated the effects of slow-release implants containing the gonadotrophin-releasing hormone (GnRH) agonist Deslorelin on reproduction in the common brushtail possum (Trichosurus vulpecula). Captive female brushtail possums were assigned to control (placebo implant), low dose (4.7 mg Deslorelin) or high dose (9.4 mg Deslorelin) groups; males were assigned to control or high dose (9.4 mg Deslorelin) groups. The acute effects of Deslorelin treatment at the level of the pituitary gland were similar between the two sexes, where a transient rise in luteinising hormone concentration was induced over the first 24 h. In females, this was associated with the disruption of the normal oestrous cycle and mating within 2-10 days in some treated individuals, but no young were subsequently detected. By 3 weeks after treatment, treated females became anoestrus and remained infertile for at least one breeding season. The effects of treatment were reversible in a subset of females that had their implants removed, although the time taken to produce offspring was variable. Paradoxically, male brushtail possums remained fertile during chronic Deslorelin exposure. Despite significant declines in basal follicle-stimulating hormone and testosterone concentrations, as well as an inability to respond to a GnRH challenge, treated males sired as many offspring as control males and there was no evidence of testicular regression. In conclusion, there is potential to control reproduction in female brushtail possums by using chronic GnRH agonist treatment.
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long term effects of Deslorelin implants on reproduction in the female tammar wallaby macropus eugenii
Reproduction, 2005Co-Authors: Catherine A Herbert, Geoff Shaw, T E Trigg, Douglas C Eckery, D. W. CooperAbstract:The contraceptive and endocrine effects of long-term treatment with implants containing the GnRH agonist Deslorelin were investigated in female tammar wallabies (Macropus eugenii). Fertility was successfully inhibited for 515 +/- 87 days after treatment with a 5 mg Deslorelin implant (n = 7), while control animals gave birth to their first young 159 +/- 47 days after placebo implant administration (n = 8). The duration of contraception was highly variable, ranging from 344 to 761 days. The strict reproductive seasonality in the tammar wallaby was maintained once the implant had expired. This inhibition of reproduction was associated with a significant reduction in basal LH concentrations and a cessation of oestrous cycles, as evidenced by low progesterone concentrations. There was evidence to suggest that some aspect of either blastocyst survival, luteal reactivation, pregnancy or birth may be affected by Deslorelin treatment in some animals. These results show that long-term inhibition of fertility in the female tammar wallaby is possible using slow-release Deslorelin implants. The effects of Deslorelin treatment were fully reversible and there was no evidence of negative side effects. Slow-release GnRH agonist implants may represent a practicable method for reproductive management of captive and semi-wild populations of marsupials.
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effects of a gonadotropin releasing hormone agonist implant on reproduction in a male marsupial macropus eugenii
Biology of Reproduction, 2004Co-Authors: Catherine A Herbert, Geoff Shaw, T E Trigg, Douglas C Eckery, Marilyn B Renfree, D. W. CooperAbstract:This study evaluated the potential of slow-release GnRH agonist (Deslorelin) implants to inhibit reproductive function in the male tammar wallaby. The specific aim was to measure the effects of graded dosages of Deslorelin on testes size and plasma LH and testosterone concentrations. Adult male tammar wallabies were assigned to four groups (n = 6 per group) and received the following treatment: control, placebo implant; low dose, 5 mg Deslorelin; medium dose, 10 mg; high dose, 20 mg. All dosages of Deslorelin induced acute increases (P 0.05). These results suggest that the male tammar wallaby is resistant to the contraceptive effects of chronic GnRH agonist treatment. Despite the maintenance of testosterone secretion, the majority of male tammars (10 of 17) failed to respond to a GnRH challenge with a release of LH between Days 186 and 197 of treatment. The failure of animals to respond to exogenous GnRH suggests a direct effect of Deslorelin on the pituitary, resulting in a level of desensitization that was sufficient to inhibit a LH surge but insufficient to inhibit basal LH secretion. The variation between animals is believed to result from earlier recovery of some individuals, in particular those that received a lower dose, or individual resistance to the desensitization process.
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effects of a gonadotropin releasing hormone agonist implant on reproduction in a male marsupial macropus eugenii
Biology of Reproduction, 2004Co-Authors: Catherine A Herbert, Geoff Shaw, T E Trigg, Douglas C Eckery, Marilyn B Renfree, D. W. CooperAbstract:This study evaluated the potential of slow-release GnRH agonist (Deslorelin) implants to inhibit reproductive function in the male tammar wallaby. The specific aim was to measure the effects of graded dosages of Deslorelin on testes size and plasma LH and testosterone concentrations. Adult male tammar wallabies were assigned to four groups (n 5 6 per group) and received the following treatment: control, placebo implant; low dose, 5 mg Deslorelin; medium dose, 10 mg; high dose, 20 mg. All dosages of Deslorelin induced acute increases (P , 0.001) in plasma LH and testosterone concentrations within 2 h, with concentrations remaining elevated during the first 24 h but returning to pretreatment levels by Day 7. Thereafter, there was no evidence of a treatment-induced decline in plasma testosterone concentrations. There was no detectable difference in basal LH concentrations between treated and control animals, nor was there a significant change in testes width or length (P . 0.05). These results suggest that the male tammar wallaby is resistant to the contraceptive effects of chronic GnRH agonist treatment. Despite the maintenance of testosterone secretion, the majority of male tammars (10 of 17) failed to respond to a GnRH challenge with a release of LH between Days 186 and 197 of treatment. The failure of animals to respond to exogenous GnRH suggests a direct effect of Deslorelin on the pituitary, resulting in a level of desensitization that was sufficient to inhibit a LH surge but insufficient to inhibit basal LH secretion. The variation between animals is believed to result from earlier recovery of some individuals, in particular those that received a lower dose, or individual resistance to the desensitization process.
T E Trigg - One of the best experts on this subject based on the ideXlab platform.
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morphological study of the effects of the gnrh superagonist Deslorelin on the canine testis and prostate gland
Reproduction in Domestic Animals, 2009Co-Authors: Aris Junaidi, T E Trigg, P Williamson, James M Cummins, Graeme MartinAbstract:The present study is part of a programme of research designed to evaluate the efficacy of the GnRH superagonist,Deslorelin (D-Trp6-Pro9-des-Gly10-LHRH ethylamide), as a contraceptive for male dogs. Adult dogs were assigned to a completely randomized design comprising six groups of four animals. Each dog in the control group received a blank implant (placebo) and each dog in the other five groups received a 6 mg Deslorelin implant. One group of Deslorelin treated dogs was sacrificed on each of days 16, 26, 41, 101 and 620, and testicular and prostate tissues were collected for study by light and electron microscopy. On days 16 and 26 after implantation, we observed partial disruption of the seminiferous tubules, with early spermatids shed into the lumen. On days 41 and 101 after implantation, 90–100% of the seminiferous tubules were atrophic and aspermatogenic.On day 101 after implantation, 99% of all sections showed atrophy of the epithelium and shrinkage of epithelial height in the ductus epididymides. On days 41 and 101 after implantation, prostate tissue showed complete atrophy of the glandular epithelium (100% of sections) and an apparent increase in the relative proportion of connective tissue. At the electron microscopic level, in dogs treated with Deslorelin for 41 and 101 days, the Sertoli cells were smaller and their nucleoli appeared smaller than in the control dogs. The nucleoli of the Leydig cells were atrophied and prostate glandular epithelium showed reduced epithelial height, a trophy of the nucleolus and an absence of secretory granules.Tissues collected during the recovery phase revealed a complete recovery of spermatogenesis. In conclusion, slow release implants containing Deslorelin induce a striking a trophy of the testes and prostate gland by 26 days after implantation, explaining the previously reported loss of ejaculate and arrest of sperm output. At histological level,the entire process appears to be completely reversible, in accordance with data on endocrine variables and semen production.
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dose response studies for pituitary and testicular function in male dogs treated with the gnrh superagonist Deslorelin
Reproduction in Domestic Animals, 2009Co-Authors: Graeme Martin, Margaret Blackberry, Aris Junaidi, P Williamson, James M Cummins, T E TriggAbstract:We tested the effect of dose of GnRH superagonist on pituitary and testicular function in a study with four groups of four male dogs. The Controls received blank implants and the other three groups received implants containing 3, 6 or 12 mg Deslorelin (d-Trp 6-Pro 9-des-Gly 10-GnRH ethylamide). In all Deslorelin-treated groups, there was initially an acute increase in plasma concentrations of LH and testosterone, followed by declines such that both hormones became undetectable after approximately 12 days. There was a dose-response in some of these early aspects of the hormone profiles. With respect to long-term effects of treatment, the 12-mg dose had significantly greater effects than the smaller doses for the duration of minimum testicular volume [366 ± 77, mean ± SEM (3 mg), 472 ± 74 (6 mg), and 634 ± 59 (12 mg) days], absence of ejaculate [416 ± 88 (3 mg), 476 ± 83 (6 mg), and 644 ± 67 (12 mg) days], undetectable plasma concentrations of LH and testosterone [367 ± 64 (3 mg), 419 ± 72 (6 mg), and 607 ± 69 (12 mg) days], the delay until complete recovery of LH and testosterone secretion [394 ± 65 (3 mg), 484 ± 72 (6 mg) and 668 ± 47 (12 mg) days], and the delay until testes had regrown to normal volume [408 ± 77 (3 mg), 514 ± 74 (6 mg), 676 ± 59 (12 mg) days]. The time taken to restore full ejaculates was also longest for the 12-mg dose: 716 ± 67 (12 mg) days vs 440 ± 66 (3 mg) and 538 ± 83 (6 mg) days after implantation. There was no correlation between delay to recovery of normal ejaculate quality and body mass. We conclude that the dose-response relationship with Deslorelin implants is not expressed with respect to the degree of suppression of reproduction, but on the maximum duration of suppression and thus to delay until recovery.
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use of a gonadotropin releasing hormone agonist implant as an alternative for surgical castration in male ferrets mustela putorius furo
Theriogenology, 2008Co-Authors: Nico J. Schoemaker, T E Trigg, Andrea Kuijten, R Van Deijk, B Muijlaert, Marja Kik, F H De Jong, C L J J Kruitwagen, J A MolAbstract:Surgical castration in ferrets has been implicated as an etiological factor in the development of hyperadrenocorticism in this species due to a castration-related increase in plasma gonadotropins. In search for a suitable alternative, the effect of treatment with the depot GnRH-agonist implant, Deslorelin, on plasma testosterone concentrations and concurrent testes size, spermatogenesis, and the typical musky odor of intact male ferrets was investigated. Twenty-one male ferrets, equally divided into three groups, were either surgically castrated, received a slow release Deslorelin implant or received a placebo implant. Plasma FSH and testosterone concentrations, testis size and spermatogenesis were all suppressed after the use of the Deslorelin implant. The musky odor in the ferrets which had received a Deslorelin implant was less compared to the ferrets which were either surgically castrated or had received a placebo implant. These results indicate that the Deslorelin implant effectively prevents reproduction and the musky odor of intact male ferrets and is therefore considered a suitable alternative for surgical castration in these animals.
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effects of Deslorelin implants on reproduction in the common brushtail possum trichosurus vulpecula
Reproduction Fertility and Development, 2007Co-Authors: Jutta Eymann, Catherine A Herbert, D. W. Cooper, T E Trigg, Douglas C Eckery, Brian P ThomsonAbstract:The present study investigated the effects of slow-release implants containing the gonadotrophin-releasing hormone (GnRH) agonist Deslorelin on reproduction in the common brushtail possum (Trichosurus vulpecula). Captive female brushtail possums were assigned to control (placebo implant), low dose (4.7 mg Deslorelin) or high dose (9.4 mg Deslorelin) groups; males were assigned to control or high dose (9.4 mg Deslorelin) groups. The acute effects of Deslorelin treatment at the level of the pituitary gland were similar between the two sexes, where a transient rise in luteinising hormone concentration was induced over the first 24 h. In females, this was associated with the disruption of the normal oestrous cycle and mating within 2-10 days in some treated individuals, but no young were subsequently detected. By 3 weeks after treatment, treated females became anoestrus and remained infertile for at least one breeding season. The effects of treatment were reversible in a subset of females that had their implants removed, although the time taken to produce offspring was variable. Paradoxically, male brushtail possums remained fertile during chronic Deslorelin exposure. Despite significant declines in basal follicle-stimulating hormone and testosterone concentrations, as well as an inability to respond to a GnRH challenge, treated males sired as many offspring as control males and there was no evidence of testicular regression. In conclusion, there is potential to control reproduction in female brushtail possums by using chronic GnRH agonist treatment.
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a review of advances in the use of the gnrh agonist Deslorelin in control of reproduction
Theriogenology, 2006Co-Authors: T E Trigg, A G Doyle, J Walsh, T SwangchanuthaiAbstract:The prevention of breeding in animals using GnRH analogues has been the object of research over many years. Recently, a new drug delivery formulation was developed which enabled the development of products that could be commercialised for veterinary use. The formulation has now been approved in certain countries for use in male dogs, and applications are being expanded to cover repeat usage, extended duration, use in females, other indications and other animal species. With respect to repeat usage, dogs have been re-implanted for four consecutive doses and monitored until they returned to normal steroidogenesis. All dogs returned to normal steroidogenesis following cessation of treatment. In females, it was previously shown that implanted bitches with progesterone <5 ng/mL at the time of implantation had an induced estrus. In a new study at Chulalongkorn University, implanting female pups at around 4 mo prevented this occurrence, whereas implantation at 7 mo did not.
Geoff Shaw - One of the best experts on this subject based on the ideXlab platform.
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Deslorelin implants in free ranging female eastern grey kangaroos macropus giganteus mechanism of action and contraceptive efficacy
Wildlife Research, 2013Co-Authors: Michelle E Wilson, Geoff Shaw, Graeme Coulson, Marilyn B RenfreeAbstract:Context. Fertility control offers a non-lethal management technique for iconic yet overabundant wildlife. Slow-release hormonal implants containing Deslorelin show promise for managing free-ranging populations, particularly in peri-urban reserves, but most studies have been limited to captivity. Aims.We investigated the efficacy and mechanism of Deslorelin implants in free-ranging female eastern grey kangaroos (Macropus giganteus) under realistic management conditions. Methods. We assigned females to a Deslorelin (9.4mg, n=53) or placebo (n=56) group at three peri-urban sites in Victoria, Australia, and monitored reproductive success for 3 years by observing young in the pouch. We tested the plasma LH response of control and treated females to exogenous GnRH, and compared the size of ovarian follicles between the two groups. Key results. Deslorelin implants reduced fertility at all three sites. No Deslorelin-treated females bred in Year 1 at Anglesea and Serendip versus 42% and 44% of control females respectively. At Plenty Gorge, 60% of Deslorelin-treated females bred in Year 1 versus 100% of control females. In Year 2, between 11% and 39% of the treated females bred versus between82%and100%ofcontrolfemalesatallsites.ThecontraceptiveefficacyreducedbyYear3whenbetween43%and 57% of the treated females bred versus between 85% and 100% of controls. A GnRH challenge elicited higher plasma LH concentrations in control than in treated females, and unlike untreated females, treated females lacked ovarian follicles >2mm. Conclusions. Deslorelin implants reduced fertility in free-ranging female eastern grey kangaroos over three successive breeding seasons. Chronic exposure to Deslorelin desensitised the pituitary gland to GnRH and suppressed follicular development, but did not inhibit the development of a blastocyst, pregnancy or lactation in at least some females that had conceived before treatment. Implications. Effective population management using Deslorelin implants will require females to be re-treated on multiple occasions because the contraceptive effect lasts only a portion of their reproductive life. This would be practical only at sites where kangaroos are relatively easy to capture. The timing of treatment is also important in a species that undergoes embryonic diapause, particularly at sites providing high-quality habitat.
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long term effects of Deslorelin implants on reproduction in the female tammar wallaby macropus eugenii
Reproduction, 2005Co-Authors: Catherine A Herbert, Geoff Shaw, T E Trigg, Douglas C Eckery, D. W. CooperAbstract:The contraceptive and endocrine effects of long-term treatment with implants containing the GnRH agonist Deslorelin were investigated in female tammar wallabies (Macropus eugenii). Fertility was successfully inhibited for 515 +/- 87 days after treatment with a 5 mg Deslorelin implant (n = 7), while control animals gave birth to their first young 159 +/- 47 days after placebo implant administration (n = 8). The duration of contraception was highly variable, ranging from 344 to 761 days. The strict reproductive seasonality in the tammar wallaby was maintained once the implant had expired. This inhibition of reproduction was associated with a significant reduction in basal LH concentrations and a cessation of oestrous cycles, as evidenced by low progesterone concentrations. There was evidence to suggest that some aspect of either blastocyst survival, luteal reactivation, pregnancy or birth may be affected by Deslorelin treatment in some animals. These results show that long-term inhibition of fertility in the female tammar wallaby is possible using slow-release Deslorelin implants. The effects of Deslorelin treatment were fully reversible and there was no evidence of negative side effects. Slow-release GnRH agonist implants may represent a practicable method for reproductive management of captive and semi-wild populations of marsupials.
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effects of a gonadotropin releasing hormone agonist implant on reproduction in a male marsupial macropus eugenii
Biology of Reproduction, 2004Co-Authors: Catherine A Herbert, Geoff Shaw, T E Trigg, Douglas C Eckery, Marilyn B Renfree, D. W. CooperAbstract:This study evaluated the potential of slow-release GnRH agonist (Deslorelin) implants to inhibit reproductive function in the male tammar wallaby. The specific aim was to measure the effects of graded dosages of Deslorelin on testes size and plasma LH and testosterone concentrations. Adult male tammar wallabies were assigned to four groups (n = 6 per group) and received the following treatment: control, placebo implant; low dose, 5 mg Deslorelin; medium dose, 10 mg; high dose, 20 mg. All dosages of Deslorelin induced acute increases (P 0.05). These results suggest that the male tammar wallaby is resistant to the contraceptive effects of chronic GnRH agonist treatment. Despite the maintenance of testosterone secretion, the majority of male tammars (10 of 17) failed to respond to a GnRH challenge with a release of LH between Days 186 and 197 of treatment. The failure of animals to respond to exogenous GnRH suggests a direct effect of Deslorelin on the pituitary, resulting in a level of desensitization that was sufficient to inhibit a LH surge but insufficient to inhibit basal LH secretion. The variation between animals is believed to result from earlier recovery of some individuals, in particular those that received a lower dose, or individual resistance to the desensitization process.
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effects of a gonadotropin releasing hormone agonist implant on reproduction in a male marsupial macropus eugenii
Biology of Reproduction, 2004Co-Authors: Catherine A Herbert, Geoff Shaw, T E Trigg, Douglas C Eckery, Marilyn B Renfree, D. W. CooperAbstract:This study evaluated the potential of slow-release GnRH agonist (Deslorelin) implants to inhibit reproductive function in the male tammar wallaby. The specific aim was to measure the effects of graded dosages of Deslorelin on testes size and plasma LH and testosterone concentrations. Adult male tammar wallabies were assigned to four groups (n 5 6 per group) and received the following treatment: control, placebo implant; low dose, 5 mg Deslorelin; medium dose, 10 mg; high dose, 20 mg. All dosages of Deslorelin induced acute increases (P , 0.001) in plasma LH and testosterone concentrations within 2 h, with concentrations remaining elevated during the first 24 h but returning to pretreatment levels by Day 7. Thereafter, there was no evidence of a treatment-induced decline in plasma testosterone concentrations. There was no detectable difference in basal LH concentrations between treated and control animals, nor was there a significant change in testes width or length (P . 0.05). These results suggest that the male tammar wallaby is resistant to the contraceptive effects of chronic GnRH agonist treatment. Despite the maintenance of testosterone secretion, the majority of male tammars (10 of 17) failed to respond to a GnRH challenge with a release of LH between Days 186 and 197 of treatment. The failure of animals to respond to exogenous GnRH suggests a direct effect of Deslorelin on the pituitary, resulting in a level of desensitization that was sufficient to inhibit a LH surge but insufficient to inhibit basal LH secretion. The variation between animals is believed to result from earlier recovery of some individuals, in particular those that received a lower dose, or individual resistance to the desensitization process.