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Special Species Health Service, Department of Surgical Sciences, School of Veterinary Medicine, University of Wisconsin, 2015 Linden Drive, Madison, WI 53706, USA
Gonadotropin-releasing hormone (GnRH) is a peptide hormone that acts as the main link between the neural and endocrine system, controlling reproduction in birds and mammals.
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The physiologic GnRH release from the hypothalamus occurs in a pulsatile fashion and GnRH receptors are predominately found on the anterior pituitary, regulating the synthesis and release of gonadotropins in birds.
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Administration of long-acting formulations of synthetic GnRH super-agonists (eg Leuprolide, Deslorelin) leads to a reduction of gonadal hormone secretion by overriding the physiologic pulsatile GnRH release from the hypothalamus.
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Deslorelin acetate implants are effective in suppressing gonadal activity in birds. The average duration of action of the 4.7-mg implant is approximately 3 months.
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The 9.5-mg deslorelin implants may achieve a longer duration of action. Significant species differences exist.
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Leuprolide acetate is effective in suppressing gonadal activity in birds. The duration of action is about 2 to 3 weeks.
Introduction
Disorders of the reproductive tract in captive birds are amongst the most common reasons for seeking veterinary care. Although reproductive disorders, such as chronic egg laying, oviductal disease, ovarian disease, and testicular tumors, are relatively easy to diagnose in avian patients, the treatment of these disorders remains challenging. In contrast to many diseases seen in dogs and cats, no scientific studies are available that compare outcome and survival times of medical versus surgical treatments in birds suffering from reproductive disorders. Therefore, it remains challenging to make scientifically sound recommendations to clients who are seeking to make an informed decision about the best treatment options available.
Surgical treatment options as the sole therapy for reproductive disorders in birds carry a guarded to poor prognosis in most cases. Although surgical correction is curative for certain disease presentations, such as oviductal prolapse or oviductal impaction, the inability to completely remove the ovary surgically can predispose birds to secondary complications, such as egg-yolk coelomitis due to persistent ovarian activity. Therefore, significant environmental adjustments to minimize triggering of reproductive activity, as well as medical treatments, may be required to prevent continued ovarian activity and ovulation. In other reproductive diseases, such as ovarian neoplasia or ovarian cysts, surgical intervention will not achieve cure, but may lead to only temporary improvement of the clinical signs. Considering the significant surgical and anesthetic risks of coelomic surgery, particularly in small avian patients, medical treatment options are often more feasible, less expensive, and therefore more frequently considered by veterinarians and clients. Over the past years, clinical use of gonadotropin-releasing hormone (GnRH) agonists for treatment of avian reproductive disorders has been increasingly reported, and several prospective research studies evaluating the efficacy of long-acting GnRH agonists in birds have been published.
Evaluation of the efficacy and safety of single administration of 4.7-mg deslorelin acetate implants on egg production and plasma sex hormones in Japanese quail (Coturnix coturnix japonica).
Nooan B, Johnson P, Matos D. Evaluation of egg-laying suppression effects of the GnRH agonist deslorelin in domestic chicken. Paper presented at: Proc Annu Conf Ass Avian Vet, 2012.
De Wit M, Westerhof I, Pefold LM. Effect of leuprolide acetate on avian reproduction. Proceedings of the Association of Avian Veterinarians. New Orleans (LA): 2004. p. 73–4.
Schmidt F, Legler M, Einspanier A, et al. Influence of the GNRH slow release agonist deslorelin on gonadal activity of the Japanese quail. 1st International Conference on Avian, Herpetological and Exotic Mammal Medicine. Wiesbaden, April 20–26, 2013. p. 501–2.
Neither medical nor surgical treatments alone or combined are likely to completely resolve disorders due to chronic gonadal activity in psittacines and passerines. Identifying and correcting the environmental factors that may trigger continued reproductive activity, such as the availability of nesting sites, shredding of paper, feeding warm and soft foods (eg, hand-feeding formula, oatmeal, cooked vegetables), excessive availability of food, foods of high energy density (seeds, corn, grains, table food), excessive daylight exposure, and inappropriate petting, is critical in helping manage these challenging cases.
Neuroendocrine Control of Reproduction and the Hypothalamic-Pituitary-Gonadal Axis
The reproductive physiology in birds, as in mammals, is under the control of the hypothalamic-pituitary-gonadal (HPG) axis.
A range of hormones, including GnRH, gonadotropin-inhibiting hormone (GnIH), vasoactive intestinal peptide, prolactin, luteinizing hormone (LH), and follicle-stimulating hormone (FSH), are responsible for the neuroendocrine regulation of reproduction in birds.
In birds, as in other vertebrates, the hypothalamic decapeptide GnRH is the primary factor responsible for the hypothalamic control of gonadotropin secretion.
GnRH plays a key role in the control of sexual maturity, ovulation rate, semen production, incubation, photorefractoriness, and reproductive aging, which all appear to be related to alterations in GnRH regulation.
GnRH acts as the main link of the central nervous system, which receives environmental visual and tactile input (eg, daylight exposure, food availability, tactile stimulation, courtship display) with the endocrine system represented by the anterior pituitary and the gonads. These environmental cues lead to increased release of short-lived GnRH (half-life of 3 to 4 minutes) in a pulsatile fashion from the hypothalamus into the hypophyseal portal vasculature and reaches the anterior pituitary gland, where GnRH receptors are expressed. GnRH receptors on the anterior pituitary gland control synthesis and release of gonadotropins and, therefore, gonadal function and hormone production.
Three different forms of GnRH have been identified in birds: avian GnRH-1 (aGnRH-1),
Identification of the second gonadotropin-releasing hormone in chicken hypothalamus: evidence that gonadotropin secretion is probably controlled by two distinct gonadotropin-releasing hormones in avian species.
Active immunization against aGnRH-1, but not against aGnRH-2, in chickens resulted in complete suppression of egg production and a decrease in plasma LH concentration, in contrast to repeated active immunization against aGnRH-2, which had no impact on egg production or plasma LH concentration.
Changes in the hypothalamic contents of LHRH-I and -II and in pituitary responsiveness to synthetic chicken LHRH-I and -II during the progesterone-induced surge of LH in the laying hen.
Three different GnRH receptor subtypes are described in mammals, and 2 of those subtypes (GnRH-R-1 and GnRH-R-3) have also been demonstrated to exist in birds.
It is unknown if the differences in avian GnRH or the expression of GnRH receptors in birds are responsible for the reduced efficacy of synthetic mammalian GnRH supra-agonist (eg, leuprolide acetate). In chickens, a pronounced response following administration a synthetic long-acting GnRH agonist was reported,
Nooan B, Johnson P, Matos D. Evaluation of egg-laying suppression effects of the GnRH agonist deslorelin in domestic chicken. Paper presented at: Proc Annu Conf Ass Avian Vet, 2012.
De Wit M, Westerhof I, Pefold LM. Effect of leuprolide acetate on avian reproduction. Proceedings of the Association of Avian Veterinarians. New Orleans (LA): 2004. p. 73–4.
In mammals, long-acting GnRH supra-agonist deslorelin acetate shows a great variability of potency and therefore significant interspecies differences in clinical efficacy have to be expected.
Although the full biologic potency of commonly used long-acting synthetic GnRH agonists (ie, deslorelin acetate, leuprolide acetate) in birds is unknown, significant species differences should also be considered in interpreting clinical reports of their use in birds or experimental studies.
Use of GnRH agonists
Synthetic GnRH agonists have a higher affinity to GnRH receptors (super-agonists) and a longer half-life compared with endogenous GnRH.
Its agonistic action will lead to an increased expression and release of gonadotropins from the pituitary into the blood, and thus leading to increased gonadal sex hormone production and development and activity of the gonads in both sexes. Examples for GnRH agonists used for their agonistic actions in veterinary medicine include its use in domestic mammals to induce estrus.
A short-acting form of the GnRH agonist buserelin has also been used to assess the testosterone secretory capacity in cockatiels (Nymphicus hollandicus) and sulphur-crested cockatoos (Cacatua galerita).
Using a GnRH agonist to obtain an index of testosterone secretory capacity in the cockatiel (Nymphicus hollandicus) and sulphur-crested cockatoo (Cacatua galerita).
Using a GnRH agonist to obtain an index of testosterone secretory capacity in the cockatiel (Nymphicus hollandicus) and sulphur-crested cockatoo (Cacatua galerita).
Because endogenous GnRH is short-lived and released in a pulsatile fashion from the hypothalamus, with the prolonged administration of synthetic GnRH super-agonists (either by sustained-release formulations or repeated administration), the initial stimulatory gonadotropic effect will be replaced by a prolonged antigonadotropic effect and consequently gonadal hormone synthesis and release is reduced.
In cases in which long-acting GnRH agonists are used with the intention to downregulate the reproductive system, the initial stimulatory effect, before its prolonged anti-gonadotropic effects is of concern, and might result in initial worsening of clinical signs related to increased gonadal hormone production.
In birds, several publications are available evaluating the use of long-acting formulations of GnRH agonists either as an injection (ie, leuprolide acetate)
De Wit M, Westerhof I, Pefold LM. Effect of leuprolide acetate on avian reproduction. Proceedings of the Association of Avian Veterinarians. New Orleans (LA): 2004. p. 73–4.
Zantop D. Using leuprolide acetate to manage common avian reproductive problems. Proceedings of the Second International Conference on Exotics. Fort Lauderdale (FL): 2000. p. 70.
Evaluation of the efficacy and safety of single administration of 4.7-mg deslorelin acetate implants on egg production and plasma sex hormones in Japanese quail (Coturnix coturnix japonica).
Nooan B, Johnson P, Matos D. Evaluation of egg-laying suppression effects of the GnRH agonist deslorelin in domestic chicken. Paper presented at: Proc Annu Conf Ass Avian Vet, 2012.
Straub J, Zenker I. First experience in hormonal treatment of sertoli cell tumors in budgerigars (M. undulates) with absorbable extended release GnRH chips (Suprelorin®) 1st International Conference on Avian, Herpetological and Exotic Mammal Medicine. Wiesbaden, April 20–26, 2013. p. 299–301.
Nemetz L. Deslorelin acetate long-term suppression of ovarian carcinoma in a cockatiel (Nymphicus hollandicus). Proc Annu Conf Associ Avian Vet. 2012. p. 37–42.
Van Sant F, Sundaram A. Retrospective study of deslorelin acetate implants in clinical practice. Paper presented at: Proc Annu Conf Associ Avian Vet. 2013.
Leuprolide acetate is the most commonly used GnRH agonist in human medicine and has been used since 1985 for its antigonadotropic effects to treat a variety of conditions, including prostatic hyperplasia and neoplasia, endometriosis, uterine fibroids, and central precious puberty.
Leuprolide is available in different formulations. The slow-release depot formulations of leuprolide are used to suppress the reproductive system, by a steady, nonpulsatile release, whereas short-acting (nondepot) formulations will have a stimulating (agonistic) effect and will lead to an increased release of LH and FSH from the pituitary, and consequently gonadal steroid hormones. The depot formulations contain biodegradable microspheres, which will continuously release leuprolide acetate over a certain amount of time. Different depot formulations (1, 3, and 4 months) are available, but the 1-month product has been used most frequently in avian medicine.
The duration of effect of the 1-month depot formulation of leuprolide acetate in birds is generally reported to be less than 4 weeks. In nonbreeding Hispaniolan Amazon parrots (Amazona ventralis), the administration of 800 μg IM leuprolide acetate resulted in reduced plasma sex hormone levels for less than 21 days.
In cockatiels treated with leuprolide before the onset of breeding, treatment resulted in a delay of egg laying by 12 to 19 days compared with the control group.
If leuprolide acetate was administered at 1456 μg/kg or 4368 μg/kg, a significant delay in onset of breeding was seen, whereas birds treated with 476 μg/kg showed no significant response.
In racing pigeons (Columbia livia domestica) the administration of leuprolide acetate at 500 and 1000 μg/kg did not have any effect on egg production or plasma sex hormone levels.
De Wit M, Westerhof I, Pefold LM. Effect of leuprolide acetate on avian reproduction. Proceedings of the Association of Avian Veterinarians. New Orleans (LA): 2004. p. 73–4.
Nemetz L. Deslorelin acetate long-term suppression of ovarian carcinoma in a cockatiel (Nymphicus hollandicus). Proc Annu Conf Associ Avian Vet. 2012. p. 37–42.
Because complete ovariectomy is clinically not feasible, medical treatment options with sustained-release GnRH agonists may offer improvement of the clinical condition. In one published paper two cockatiels were managed with repeated coelomocentesis and GnRH agonists and survived for 9 and 25 months respectively.
If intracoelomic fluid accumulation causes respiratory compromise coelomocentesis and aspiration of fluid is recommended to provide rapid improvement (Fig. 1).
Fig. 1Coelomic distension and body wall herniation in a female cockatiel (A) and female budgerigar (B) due to coelomic effusion secondary to ovarian pathology.
The clinical use of longer-acting depot formulations of leuprolide (3 and 4 month) has been anecdotally reported, but references on the efficacy and duration of effect are unavailable.
In about 20 years of use of leuprolide acetate in avian patients, only one report exists about the suspected anaphylactic reaction and death in 2 elf owls (Micrathene whitneyi) following administration of leuprolide acetate from the same vial.
Treatment of queens in estrus and after estrus with a GnRH-agonist implant containing 4.7 mg deslorelin; hormonal response, duration of efficacy, and reversibility.
Commercial forms of deslorelin acetate (eg, Suprelorin; Peptech Animal Health Pty Ltd, Macquarie Park, NSW, Australia) are currently approved for use in veterinary medicine to induce ovulation in mares as part of the artificial insemination process, to stabilize high-risk pregnancies in livestock, as contraception in dogs, and for the treatment of adrenal endocrinopathy in ferrets.
Straub J, Zenker I. First experience in hormonal treatment of sertoli cell tumors in budgerigars (M. undulates) with absorbable extended release GnRH chips (Suprelorin®) 1st International Conference on Avian, Herpetological and Exotic Mammal Medicine. Wiesbaden, April 20–26, 2013. p. 299–301.
Nemetz L. Deslorelin acetate long-term suppression of ovarian carcinoma in a cockatiel (Nymphicus hollandicus). Proc Annu Conf Associ Avian Vet. 2012. p. 37–42.
Van Sant F, Sundaram A. Retrospective study of deslorelin acetate implants in clinical practice. Paper presented at: Proc Annu Conf Associ Avian Vet. 2013.
Nooan B, Johnson P, Matos D. Evaluation of egg-laying suppression effects of the GnRH agonist deslorelin in domestic chicken. Paper presented at: Proc Annu Conf Ass Avian Vet, 2012.
Evaluation of the efficacy and safety of single administration of 4.7-mg deslorelin acetate implants on egg production and plasma sex hormones in Japanese quail (Coturnix coturnix japonica).
Mans C, Braun JM, Feeney M. Intranasal sedation with midazolam or midazolam-butorphanol in psittacine birds: a retrospective evaluation of 114 cases (2010-2012). 1st International Conference on Avian, Herpetological and Exotic Mammal Medicine. Wiesbaden, April 20–26, 2013. p. 292.
n = 4 males/7 female nonbreeding birds, plasma androstenedione and 17-beta–estradiol levels significantly reduced by day 7, but not by day 21. No effect on LH levels.
De Wit M, Westerhof I, Pefold LM. Effect of leuprolide acetate on avian reproduction. Proceedings of the Association of Avian Veterinarians. New Orleans (LA): 2004. p. 73–4.
Nooan B, Johnson P, Matos D. Evaluation of egg-laying suppression effects of the GnRH agonist deslorelin in domestic chicken. Paper presented at: Proc Annu Conf Ass Avian Vet, 2012.
Nooan B, Johnson P, Matos D. Evaluation of egg-laying suppression effects of the GnRH agonist deslorelin in domestic chicken. Paper presented at: Proc Annu Conf Ass Avian Vet, 2012.
Evaluation of the efficacy and safety of single administration of 4.7-mg deslorelin acetate implants on egg production and plasma sex hormones in Japanese quail (Coturnix coturnix japonica).
Schmidt F, Legler M, Einspanier A, et al. Influence of the GNRH slow release agonist deslorelin on gonadal activity of the Japanese quail. 1st International Conference on Avian, Herpetological and Exotic Mammal Medicine. Wiesbaden, April 20–26, 2013. p. 501–2.
In 2-year-old laying chickens (Gallus g. domesticus), the subcutaneous administration of deslorelin implants (4.7 or 9.5 mg) resulted in a complete cessation of egg laying by the second week (see Table 1). Egg laying was suppressed for 180 days (range: 125–237 days) in chickens that received the 4.7-mg deslorelin implant, and for 319 days (range: 229–357 days) following administration of the 9.5-mg implant.
Nooan B, Johnson P, Matos D. Evaluation of egg-laying suppression effects of the GnRH agonist deslorelin in domestic chicken. Paper presented at: Proc Annu Conf Ass Avian Vet, 2012.
The deslorelin implant suppressed ovarian activity and, therefore, egg production, effectively in all chickens treated. This 100% efficacy is in contrast to studies performed in female Japanese quail (Coturnix japonica), in which deslorelin implants were effective in only 60% to 78% of the treated birds.
Evaluation of the efficacy and safety of single administration of 4.7-mg deslorelin acetate implants on egg production and plasma sex hormones in Japanese quail (Coturnix coturnix japonica).
Schmidt F, Legler M, Einspanier A, et al. Influence of the GNRH slow release agonist deslorelin on gonadal activity of the Japanese quail. 1st International Conference on Avian, Herpetological and Exotic Mammal Medicine. Wiesbaden, April 20–26, 2013. p. 501–2.
In 60% (6/10) of quail, egg production and plasma androstenedione and 17β-estradiol concentrations were significantly decreased from 2 to 12 weeks after administration of a single 4.7-mg deslorelin implant.
Evaluation of the efficacy and safety of single administration of 4.7-mg deslorelin acetate implants on egg production and plasma sex hormones in Japanese quail (Coturnix coturnix japonica).
In a second study by the same investigators, 70% of the female quail implanted with two 4.7-mg deslorelin implants produced significantly fewer eggs between week 1 and 15 following implantation. In contrast, quail implanted with a single 9.5-mg deslorelin implant showed to reduction in egg production until week 12 following implantation. Egg production was significantly less compared with the control group, from week 12 to 26.
However, the study was terminated after 26 weeks, and therefore a possibly longer effect could not be excluded. A third study in male and female Japanese quail found that a single 4.7-mg deslorelin implant was effective in 89% of the birds.
Mans C, Braun JM, Feeney M. Intranasal sedation with midazolam or midazolam-butorphanol in psittacine birds: a retrospective evaluation of 114 cases (2010-2012). 1st International Conference on Avian, Herpetological and Exotic Mammal Medicine. Wiesbaden, April 20–26, 2013. p. 292.
In female quail, egg production was reduced in 7 (78%) of 9 birds within 1 to 5 weeks postimplantation. Egg reduction was reduced for 7 to 18 weeks, with 5 of 7 birds not laying eggs for more than 14 weeks.
Schmidt F, Legler M, Einspanier A, et al. Influence of the GNRH slow release agonist deslorelin on gonadal activity of the Japanese quail. 1st International Conference on Avian, Herpetological and Exotic Mammal Medicine. Wiesbaden, April 20–26, 2013. p. 501–2.
In male quail, the duration of effect was reported to be 2 to 13 weeks, based on a substantial reduction in circulating testosterone and estrone sulfate levels (10/10 animals) and other parameters, such a size of the cloacal gland. Testosterone levels were significantly reduced in all male quail within 3 days after implant administration.
Mans C, Braun JM, Feeney M. Intranasal sedation with midazolam or midazolam-butorphanol in psittacine birds: a retrospective evaluation of 114 cases (2010-2012). 1st International Conference on Avian, Herpetological and Exotic Mammal Medicine. Wiesbaden, April 20–26, 2013. p. 292.
No adverse effects were reported in studies performed in chickens and quail. From these prospective studies, it can be concluded that significant species differences in the efficacy and duration of deslorelin implants exist and that in chickens, 9.5-mg implants provide longer suppression compared with the 4.7-mg implants.
Retrospective case series reporting the use of deslorelin implants in psittacine birds have been published in the non-peer reviewed literature.
Straub J, Zenker I. First experience in hormonal treatment of sertoli cell tumors in budgerigars (M. undulates) with absorbable extended release GnRH chips (Suprelorin®) 1st International Conference on Avian, Herpetological and Exotic Mammal Medicine. Wiesbaden, April 20–26, 2013. p. 299–301.
Van Sant F, Sundaram A. Retrospective study of deslorelin acetate implants in clinical practice. Paper presented at: Proc Annu Conf Associ Avian Vet. 2013.
In female birds suffering from chronic egg laying, a single 4.7-mg deslorelin implant suppressed egg laying for approximately 3 months in all 32 psittacine birds treated.
Van Sant F, Sundaram A. Retrospective study of deslorelin acetate implants in clinical practice. Paper presented at: Proc Annu Conf Associ Avian Vet. 2013.
Van Sant F, Sundaram A. Retrospective study of deslorelin acetate implants in clinical practice. Paper presented at: Proc Annu Conf Associ Avian Vet. 2013.
Deslorelin acetate implants have also been reported to lead to improvement of clinical signs in a case series of 9 budgerigars (Melospitacus undulatus) tentatively diagnosed with hormone-producing gonadal tumors (ie, Sertoli cell tumors).
Straub J, Zenker I. First experience in hormonal treatment of sertoli cell tumors in budgerigars (M. undulates) with absorbable extended release GnRH chips (Suprelorin®) 1st International Conference on Avian, Herpetological and Exotic Mammal Medicine. Wiesbaden, April 20–26, 2013. p. 299–301.
The tentative diagnosis was made based on brownish discoloration of the cere (Fig. 2), polyostotic hyperostosis (Fig. 3A, B), and a soft tissue mass in the coelomic cavity (see Fig. 3C, D).
Straub J, Zenker I. First experience in hormonal treatment of sertoli cell tumors in budgerigars (M. undulates) with absorbable extended release GnRH chips (Suprelorin®) 1st International Conference on Avian, Herpetological and Exotic Mammal Medicine. Wiesbaden, April 20–26, 2013. p. 299–301.
Straub J, Zenker I. First experience in hormonal treatment of sertoli cell tumors in budgerigars (M. undulates) with absorbable extended release GnRH chips (Suprelorin®) 1st International Conference on Avian, Herpetological and Exotic Mammal Medicine. Wiesbaden, April 20–26, 2013. p. 299–301.
A response to treatment was reported in 7 of 9 budgerigars, evident by a change of cere color from brownish to blue. Further improvements included resolution of previously diagnosed lameness (3/3) and an improved general condition (7/8).
Straub J, Zenker I. First experience in hormonal treatment of sertoli cell tumors in budgerigars (M. undulates) with absorbable extended release GnRH chips (Suprelorin®) 1st International Conference on Avian, Herpetological and Exotic Mammal Medicine. Wiesbaden, April 20–26, 2013. p. 299–301.
Initial clinical improvement was noted after several days to 4 weeks. Recurrence of clinical signs was noted on average 19 weeks after initial deslorelin administration. Deslorelin implants were repeatedly administered after recurrence of clinical signs and the effect of deslorelin lasted on average 20 weeks. Treatment of suspected Sertoli cell tumors in budgerigars with deslorelin implants was found to be effective by temporarily treating the clinical signs secondary to abnormal estrogen production and no significant side effects were reported.
Straub J, Zenker I. First experience in hormonal treatment of sertoli cell tumors in budgerigars (M. undulates) with absorbable extended release GnRH chips (Suprelorin®) 1st International Conference on Avian, Herpetological and Exotic Mammal Medicine. Wiesbaden, April 20–26, 2013. p. 299–301.
Fig. 3Sertoli cell tumor in a budgerigar. (A, B) Ventrodorsal and lateral survey radiograph showing increased soft tissue opacity in the coelom and hyperostosis of all bones and an increased distance between the pubic bones, secondary to hyperestrogenism. (C) Coelomic ultrasound identifying a left-sided intracoelomic mass. (D) Postmortem examination revealing a large gonadal mass (arrow), later confirmed as a Sertoli cell tumor. Note the severely enlarged vent opening, secondary to hyperestrogenism.
Avian patients should be either anesthetized or sedated for the brief implantation procedure (Fig. 4). For sedation, midazolam in combination with butorphanol has been successfully used for this procedure.
Van Sant F, Sundaram A. Retrospective study of deslorelin acetate implants in clinical practice. Paper presented at: Proc Annu Conf Associ Avian Vet. 2013.
Mans C, Braun JM, Feeney M. Intranasal sedation with midazolam or midazolam-butorphanol in psittacine birds: a retrospective evaluation of 114 cases (2010-2012). 1st International Conference on Avian, Herpetological and Exotic Mammal Medicine. Wiesbaden, April 20–26, 2013. p. 292.
Infiltration of the insertion site with lidocaine (4 mg/kg) may be beneficial if sedation is not sufficient.
Fig. 4(A) Subcutaneous administration of a deslorelin acetate implant in the area over the shoulders in a sedated green-winged macaw (Ara chloropterus). (B) Subcutaneously implanted deslorelin acetate implant (arrow) in an Umbrella cockatoo (Cacatua alba). The administration needle and syringe are shown.
Evaluation of the efficacy and safety of single administration of 4.7-mg deslorelin acetate implants on egg production and plasma sex hormones in Japanese quail (Coturnix coturnix japonica).
Schmidt F, Legler M, Einspanier A, et al. Influence of the GNRH slow release agonist deslorelin on gonadal activity of the Japanese quail. 1st International Conference on Avian, Herpetological and Exotic Mammal Medicine. Wiesbaden, April 20–26, 2013. p. 501–2.
Straub J, Zenker I. First experience in hormonal treatment of sertoli cell tumors in budgerigars (M. undulates) with absorbable extended release GnRH chips (Suprelorin®) 1st International Conference on Avian, Herpetological and Exotic Mammal Medicine. Wiesbaden, April 20–26, 2013. p. 299–301.
After routine preparation of the surgery site, the skin is slightly elevated and a small stab incision made. The implant can be placed with the delivery syringe. The injection needle should be directed from cranial to caudal to minimize the risk of loosing the implant if the skin incision potentially dehisces. For skin incision closure, either a ligature or tissue glue can be used. In some cases, in particular in small birds, it might be beneficial to use blunt hemostats, which should be inserted into the incision and directed caudally to create a pocket distal to the incision site. Removal of old implants is not necessary, but is fairly easy at the time of replacement. In smaller birds, weighing less than 50 g, implants may also be cut in half to facilitate implantation.
Van Sant F, Sundaram A. Retrospective study of deslorelin acetate implants in clinical practice. Paper presented at: Proc Annu Conf Associ Avian Vet. 2013.
However, it is currently unknown if cutting the implant in half will reduce the duration of effect.
Currently, there are no labeled contraindications for the use of deslorelin implants. The worst side effect may be failure to respond to therapy. Adverse effects may include local swelling and soreness at the implant site. In rare cases, in psittacine birds, self-mutilation of the implant site and implant removal might occur and has been reported in 3 of 96 psittacine birds.
Van Sant F, Sundaram A. Retrospective study of deslorelin acetate implants in clinical practice. Paper presented at: Proc Annu Conf Associ Avian Vet. 2013.
Evaluation of the efficacy and safety of single administration of 4.7-mg deslorelin acetate implants on egg production and plasma sex hormones in Japanese quail (Coturnix coturnix japonica).
Nooan B, Johnson P, Matos D. Evaluation of egg-laying suppression effects of the GnRH agonist deslorelin in domestic chicken. Paper presented at: Proc Annu Conf Ass Avian Vet, 2012.
De Wit M, Westerhof I, Pefold LM. Effect of leuprolide acetate on avian reproduction. Proceedings of the Association of Avian Veterinarians. New Orleans (LA): 2004. p. 73–4.
Schmidt F, Legler M, Einspanier A, et al. Influence of the GNRH slow release agonist deslorelin on gonadal activity of the Japanese quail. 1st International Conference on Avian, Herpetological and Exotic Mammal Medicine. Wiesbaden, April 20–26, 2013. p. 501–2.
Identification of the second gonadotropin-releasing hormone in chicken hypothalamus: evidence that gonadotropin secretion is probably controlled by two distinct gonadotropin-releasing hormones in avian species.
Changes in the hypothalamic contents of LHRH-I and -II and in pituitary responsiveness to synthetic chicken LHRH-I and -II during the progesterone-induced surge of LH in the laying hen.
Using a GnRH agonist to obtain an index of testosterone secretory capacity in the cockatiel (Nymphicus hollandicus) and sulphur-crested cockatoo (Cacatua galerita).
Zantop D. Using leuprolide acetate to manage common avian reproductive problems. Proceedings of the Second International Conference on Exotics. Fort Lauderdale (FL): 2000. p. 70.
Straub J, Zenker I. First experience in hormonal treatment of sertoli cell tumors in budgerigars (M. undulates) with absorbable extended release GnRH chips (Suprelorin®) 1st International Conference on Avian, Herpetological and Exotic Mammal Medicine. Wiesbaden, April 20–26, 2013. p. 299–301.
Nemetz L. Deslorelin acetate long-term suppression of ovarian carcinoma in a cockatiel (Nymphicus hollandicus). Proc Annu Conf Associ Avian Vet. 2012. p. 37–42.
Van Sant F, Sundaram A. Retrospective study of deslorelin acetate implants in clinical practice. Paper presented at: Proc Annu Conf Associ Avian Vet. 2013.
Treatment of queens in estrus and after estrus with a GnRH-agonist implant containing 4.7 mg deslorelin; hormonal response, duration of efficacy, and reversibility.
Mans C, Braun JM, Feeney M. Intranasal sedation with midazolam or midazolam-butorphanol in psittacine birds: a retrospective evaluation of 114 cases (2010-2012). 1st International Conference on Avian, Herpetological and Exotic Mammal Medicine. Wiesbaden, April 20–26, 2013. p. 292.
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