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Surgery of the avian reproductive tract
Abstract
Reproductive tract disease is commonplace in avian medicine, especially among female birds. The unique anatomy and physiology of the avian reproductive tract results in a highly productive but poorly accessible organ system. This is commonly represented as a hen producing numerous eggs and subsequently becoming “egg bound” or developing egg yolk “peritonitis”. Although many reproductive tract diseases can be managed medically, there is a definite need for surgical intervention in some cases. Because of their internal location, various diseases, and normal physiologic processes that can dramatically alter appearances, a clear understanding of the anatomy of the avian male and female reproductive tracts is vital before surgical exploration. Because of the need for small size and, again, a bird's internal anatomy, surgical instrumentation and techniques have become specialized for avian reproductive tract surgery. Anatomy, surgery, and diseases of the male and female reproductive tracts will be covered. Although some discussion of the medical management of each disease is included, the focus will be towards surgical resolution.
... Primarily due to high egg producing hens, reproductive tract diseases are common in pet and even commercial avian practice. 1 With advances in diagnostics and therapeutics available to birds, many reproductive tract diseases can be medically managed. However, several diseases can only be treated surgically. ...
... Because of past literature describing procedures such as salpingohysterectomy as 'difficult and risky', many practitioners are rightfully cautious about performing avian reproductive tract surgery. 1 As with diagnostics and therapeutics, anesthetic techniques, instrumentation, pain management, a better understanding of respiratory physiology and surgical techniques have all advanced in avian medicine. Due to medical and surgical progress and public awareness, avian practitioners are being called upon to manage more complex behavioral, medical, and surgical related problems in birds with greater success. 1 Surgeon's experience and proper instrumentation are vital to minimize tissue trauma, bleeding, and anesthetic time and to improve outcomes. ...
... Due to medical and surgical progress and public awareness, avian practitioners are being called upon to manage more complex behavioral, medical, and surgical related problems in birds with greater success. 1 Surgeon's experience and proper instrumentation are vital to minimize tissue trauma, bleeding, and anesthetic time and to improve outcomes. Analgesics should be considered in all surgical cases. ...
Reproductive tract disease is a commonplace in avian practice, particularly among female birds. Unique anatomy and physiology of the avian reproductive tract results in a highly productive but poorly accessible organ system. Affected hens are commonly presented with nonspecific lethargy, coelomic swelling and sometimes laying abnormal eggs. Reproductive diseases are less common in male birds; however, they are well described. Although many reproductive tract diseases can be managed medically, there is a definite need for surgical intervention in some cases. Because of internal location, various disease processes and even normal physiologic processes can dramatically alter patient presentations. For this reason, a clear understanding of avian female anatomy and male reproductive tracts is vital to diagnose and treat disorders. This manuscript focuses on recognition and treatment (emphasizing surgical management) of avian reproductive tract diseases. Because of the unique avian reproductive anatomy and frequent need for surgical correction of disorders, the organization of the manuscript starts with descriptions of coelom and basic surgical principles.
... Based on the sensitivity profile, the antibiotic was changed to amoxicillin (100 mg/kg PO q8h for 7 days). Leuprolide acetate (750 lg/kg IM; Lupron) was administered twice at a 2-week interval in the postoperative period to suppress ovarian activity and reduce the risk of ectopic ovulation after salpingohysterectomy. [3][4][5][6] Environmental changes such as decreasing the photoperiod, removing all nesting material, and moving the conure and her mate to a larger enclosure were recommended to the owner. The owner was instructed to transition to a 75% pelleted diet, continue feeding fresh vegetables, and avoid feeding corn, peas, beans, grains, pasta, and any soft, cooked food. ...
... A sustained-release GnRH agonist was recommended to suppress ovarian activity and reduce the risk of ectopic ovulation but was declined by the owner. [3][4][5][6] Environmental changes such as decreased light exposure and removal of nesting material were recommended. The owner was instructed to decrease feeding of high-fat foods, to avoid soft or cooked food, and to limit giving nuts and seeds, except as occasional treats. ...
... possible ectopic ovulation and secondary egg yolk peritonitis. [3][4][5][6] ...
Lateral body wall herniation with involvement of the oviduct was diagnosed in a female nanday conure (Aratinga nenday) and a female eclectus parrot (Eclectus roratus). A history of chronic egg laying and chronic reproductive activity was reported in both cases. A subcutaneous mass in the area of the caudal left lateral body wall was present in both birds. Diagnostic imaging (ultrasonography, computed tomography) and cytologic examination lead to the diagnosis of left lateral body wall herniation with involvement of the oviduct. In the conure, a developing egg was contained within the herniated oviduct. Both cases were successfully treated by salpingohysterectomy and surgical correction of the hernal ring. Lateral body wall herniation with oviductal involvement in birds has not previously been reported and should be considered as a differential for birds presenting with masses originating from the lateral body wall.
... Um dos objetivos do presente estudo foi avaliar o comportamento do ovário das aves com redução de luminosidade por 24 dias, comparando o tamanho do ovário em fase de postura por meio de videolaparoscopia e após a restrição luminosa por necropsia. Essa redução pode auxiliar no tratamento de aves de estimação que sofrem com postura crônica, retenção de ovos e outras complicações reprodutivas, bem como facilitar a cirurgia de salpingohisterectomia, recomendada nestes casos (PYE et al., 2001), por reduzir não apenas o tamanho, mas também a vascularização (BOWLES, 2002;ECHOLS, 2002 A técnica cirúrgica descrita mostrou-se útil para a avaliação do ovário de codornas-japonesas com folículos pequenos ao permitir a visualização completa do órgão e por demonstrar, à necropsia, que não houve danos ao ovário ou aos órgãos adjacentes, os quais poderiam ser ocasionados tanto pelo endoscópio como pela régua. No entanto, não possibilitou a avaliação ovariana quando havia um grande folículo amarelo de tamanho superior ao estroma ovariano na região lateral do ovário, situação na qual o campo visual do endoscópio é inteiramente tomado apenas pela imagem total ou parcial do folículo. ...
... No entanto, não possibilitou a avaliação ovariana quando havia um grande folículo amarelo de tamanho superior ao estroma ovariano na região lateral do ovário, situação na qual o campo visual do endoscópio é inteiramente tomado apenas pela imagem total ou parcial do folículo. O sítio de incisão adotado para a videolaparoscopia foi semelhante ao utilizado em técnicas de celiotomia ou endoscopia com incisão única (PYE et al., 2001;CLAYTON;RITZMAN, 2006), porém diferiu do utilizado pela maioria dos autores em técnicas de celiotomia ou salpingohisterectomia por videocirurgia (ECHOLS, 2002;HERNANDEZ-DIVERS et al., 2007;DIVERS, 2010). ...
RESUMO A redução do tamanho e da vascularização do aparelho reprodutor feminino pode auxiliar no tratamento de aves de estimação que sofrem com postura crônica e outras complicações reprodutivas e facilitar a salpingohisterectomia. Usando como modelo a codorna-japonesa (Coturnix coturnix japonica), os objetivos do presente estudo foram a obtenção de um método eficaz para realizar a mensuração ovariana por videolaparoscopia de aves em postura e avaliar qual a redução proporcionada pela restrição luminosa por um período 24 dias. Foram realizadas videolaparoscopias em 18 codornas para a mensuração ovariana por meio das imagens obtidas utilizando uma régua milimétrica especialmente confeccionada e o software ImageJ. Após, receberem oito horas diárias de luz durante 24 dias, as aves foram submetidas à eutanásia e necropsia para nova mensuração ovariana. Dezesseis codornas apresentaram folículos ovarianos excedendo o campo visual do endoscópio. A régua milimétrica e o software ImageJ foram considerados eficazes para realizar a mensuração ovariana por videolaparoscopia quando os ovários não excedem o tamanho do campo visual, porém a técnica não é indicada para a mensuração de estruturas grandes como o ovário com pleno desenvolvimento folicular. Para utilizar a técnica descrita, é necessário desenvolver um acesso cirúrgico que permita a visualização do ovário em um único campo visual em todas as fases reprodutivas.
... Diode laser excision can also be used through this approach and may be performed without the need for direct hemostasis. 10 ...
Testicular tumors of birds are best described in budgerigars (Melopsittacus undulatus) and pigeons (Columba livia).1–5 Reported tumors include seminoma, Sertoli cell tumor, interstitial cell tumor, lymphosarcoma, undifferentiated sarcoma, and teratoma.1 Seminomas and Sertoli cell tumors are the most common.1,3–8 The tumors of the testicle frequently result in testicular enlargement and usually coelomic cavity distension. Dyspnea, lethargy, anorexia, and ascites are the common clinical signs. Some Sertoli cell tumors are reported to be functional resulting in feminization with the associated change in cere color in budgerigars and feather changes in a Nyasa lovebird (Agapornis lilianae).1,5 Therapy has not been previously described in the reports from the literature as diagnosis was obtained at postmortem examination.
... Despite most of the observed tumors were related to the reproductive tract almost none of them influenced the production status of the affected hens. In birds, tumors in the reproductive tract is not uncommon (Scott Echols, 2002), however ovarian neoplasia is uncommon in hens younger than 2 yr old (Fredrickson, 1987). Very little information on the incidence of neoplasms in commercial poultry is available. ...
Apperantly healthy laying hens at the end of production (60 to 91 wk) were investigated for the occurrence of pathology and bacterial infections. In total, 7,477 hens from 15 flocks representing the following production systems: Enriched cages, barn housed layers, and organic/free range layers were necropsied. Indications of bacterial infection were investigated by bacteriological cultivation. The overall prevalence of lesions was 16.60%, including lesions of both infectious and non-infectious origin. The most prevalent lesions were bursitis presternalis (6.65%), reproductive tract lesions (e.g., salpingitis and/or peritonitis and/or oophoritis) (3.50%), serosal scarification (e.g., fibrotic adhesive peritonitis) 1.55%, and neoplasm 1.73%. Significant differences were observed between different production systems and/or flocks in the prevalence of reproductive tract lesions, bursitis presternalis, serosal scarification, skin infections, juvenile hens, and traumas/fractures. No significant difference was observed between different production systems in the prevalence of neoplasia, infection of septicemic etiology, and pododermatitis. In total, 3.4% of the hens were out of lay, with significantly higher rate in organic flocks. Infections of the reproductive tract were the most prevalent lesions with bacterial etiology in all productions systems. In total, 40% of the hens with lesions associated to the oviduct were out of lay and significant difference between production systems were observed. Escherichia coli was the most commonly isolated bacteria and in 90% of the cases they were isolated from the reproductive tract lesions. The second most prevalent bacteria was Gallibacteruim anatis. Significant difference in the prevalence of E. coli positive hens was observed between production systems (P < 0.05). In conclusion, the prevalence of reproductive tract lesions in apparently healthy end-of-lay laying was higher than indicated in previous reports. These findings support the previous suggestions that E. coli and G. anatis are the major pathogens causing reproductive tract lesions.
... The effect of luminous stimulation on bird reproductive systems is well known (Pezoa Poblete et al., 2013) and it is used in poultry science to enhance egg production (Dominoni et al., 2013). In domestic birds; however, laying eggs can be a disadvantage, since there are many reproductive tract diseases and disorders due to excessive egg laying, such as cloacal prolapse, egg binding, soft-shelled or partially formed eggs, calcium deficiency and behavior changes (Echols, 2002). ...
Often, in pet birds, any stimulus to lay eggs is unwanted in order to reduce reproductive diseases and disorders. The objectives of this study were: to determine the time necessary to promote ovary involution after an eight hour photoperiod using laying Japanese quails (Coturnix coturnix japonica); to connect the ovarian radiographic measurements with egg production; and to compare these measurements with direct ovary data obtained at necropsy. Birds were separated into three groups: 12h/24d (control group – 12h photoperiod for 24 days), 8h/24d and 8h/36d (8h photoperiod for 24 and 36 days). After euthanasia, all cadavers were x-rayed to measure ovary length and height. Birds were necropsied to measure ovarian length and weight. Results: radiographic ovary length demonstrated strong and positive correlation (r=0.96) with direct ovary length of all three groups; laying quails showed higher ovary height (p=0.025) and length (p=0.009) than non-laying quails; eight hours of artificial light per day promotes ovary length (p=0.025) and weight (p=0.009) reduction. Conclusions: radiography can estimate the ovary measure and indicate posture; an eight hour photoperiod of 24 days is not enough to promote ovarian regression, while the use of reduced photoperiod for 36 days promotes significant ovary involution.
... Many species of pet birds, including the cockatiel (Nymphicus hollandicus), lovebird (Agapornis spp), and zebra finch (Taeniopygia guttata) are prone to excessive ovulation, and ovariectomy is not a currently viable surgical procedure because of the anatomy and vascular supply of the avian ovary. Although oviductal removal or hysterectomy is reported in the literature as an effective means of inhibiting ovulation, no long-term follow-up studies document effective cessation of ovulation or the rate of abnormalities related to retention of the ovary (eg, ovarian cysts, internal laying) [114,115] . Species differences in response to oviduct removal (eg, Anseriformes versus Psittaciformes) likely also occur but, again, are poorly documented. ...
In avian species, reproductive disorders and undesirable behaviors commonly reflect abnormalities in the neuroendocrine regulation of the reproductive system. Current treatment options are often disappointing, show no long-lasting effect, or have significant side effects. A possible reason for our lack of success is a dearth of knowledge of the underlying neuroendocrine, behavioral, and autonomous physiology of the reproductive processes. Tremendous progress has been made in the last few years in our understanding of the neuroendocrine control of reproduction in birds. Advantage should be taken of these experimentally derived data to develop appropriate and safe treatment protocols for avian patients suffering from reproductive disorders.
... Despite most of the observed tumors were related to the reproductive tract almost none of them influenced the production status of the affected hens. In birds, tumors in the reproductive tract is not uncommon (Scott Echols, 2002), however ovarian neoplasia is uncommon in hens younger than 2 yr old (Fredrickson, 1987). Very little information on the incidence of neoplasms in commercial poultry is available. ...
To assess the survival of G. anatis in dead laying hens, 21-week old laying hens were injected intraperitoneally with 0.5 ml brain hearth infusion broth containing 108 CFU of G. anatis 12656-12 liver (n=16), E. coli ST141(n=16), or a mix of G. anatis 12656-12 liver (n=16) and E. coli ST141 (n=16), respectively. Birds were euthanized 24 hours post injection and eight dead birds were kept at 4°C and room temperature, respectively. Swab samples were taken at different time points post euthanization and streaked on blood agar plates. From the birds kept at 4 °C, G. anatis was re-isolated from the G. anatis and the G. anatis/E. coli co-injected groups at least 12 days post euthanization. From birds kept at room temperature, G. anatis was re-isolated up to 48 hours post euthanization. When using the gyrB based G. anatis-specific qPCR G. anatis was detected at least 120 hours and up to 96 hours post euthanized from birds kept at room temperature and 4°C, respectively. E. coli was re-isolated from all the time points independent of how the birds were kept. No difference was observed between the re-isolation rates for G. anatis or E. coli when comparing similar detection methods. For birds kept at 4°C, bacterial cultivation was a more sensitive detection method to detect G. anatis (P<0.05), while for birds kept at room temperature the G. anatis-specific qPCR out performed bacterial culture (P<0.05). In conclusion, we demonstrated that G. anatis has a poorer survival than E. coli in dead chickens kept at room temperature. That may affect the overall diagnostic sensitivity and lead to underdiagnosing of G. anatis in a normal production setting.
Systemic amyloidosis and testicular interstitial tumor are rare conditions in birds and this is the first report in Iran. A male zebra finch was presented because of white diarrhea, anorexia, loss of weight and lethargy. At necropsy, the small intestine was edematous and congested. The spleen appeared pale. The liver was large, firm and brown. One testis was cystic and neoplastic and the remaining testis was atrophic. Histologically, amyloid materials were seen predominantly in the liver and spleen. Hyaline substances were deposited in the Disse space and in the media of blood vessels of the liver. In spleen, marked deposits thickened the basement membranes of blood vessels and extended into the surrounding parenchyma. In addition, there were lesser degrees of amyloidosis in other organs such as small intestine. Amyloid stained positively with Congo red. In testis, there was encapsulated unilateral interstitial cell tumor, with multiple foci of necrosis and hemorrhage. The neoplastic cells were round to polyhedral, with small round hyperchromatic nuclei and finely vacuolated cytoplasm. Signs of feminization were observed. The cause of amyloidosis in this study was not conclusively identified.
Nowadays, contraceptives for birds are more en more used for the prevention of reproduction and for therapeutic reasons. In female animals, the indications for the use of contraceptives are abundant or chronic egglaying, eggbinding, dystocia, salpingitis, impaction of the salpinx, prolapse of the cloaca or salpinx, rupture of the salpinx, ovarian neoplasia or ovarian cysts. In male animals contraceptives are administered to obtain teaser males, to prevent reproduction, to treat testicular neoplasia and to improve the carcass quality of poultry. For several years researchers have been studying these diseases, their treatment and prevention. This review includes the hormonal therapies as well as the surgical and endoscopic contraceptive techniques. Furthermore, the reproductive anatomy and endocrinology of birds are described. In bird practices, the administration of chemical contraceptives as well as the performance of surgical techniques and endoscopies are on the increase. Since specialization is increasing rapidly in small animal practices, it can be expected that these procedures will become more frequent in the future.
Essentials of Avian Medicine and Surgery is designed as a concise quick reference for the busy practitioner and animal nurse. Eminently practical, this classic avian text is prized for its down-to-earth approach. new contributions from world renowned experts in avian medicine. new chapter on the special senses of birds, an understanding of which is crucial when giving advice on avian welfare problems. fully up-to-date on the latest diagnostic and imaging techniques. avian zoonotics are highlighted in infectious diseases section.
Systemic amyloidosis and testicular interstitial tumor are rare conditions in birds and this is the
first report in Iran. A male zebra finch was presented because of white diarrhea, anorexia, loss of
weight and lethargy. At necropsy, the small intestine was edematous and congested. The spleen
appeared pale. The liver was large, firm and brown. One testis was cystic and neoplastic and the
remaining testis was atrophic.
Histologically, amyloid materials were seen predominantly in the liver and spleen. Hyaline
substances were deposited in the Disse space and in the media of blood vessels of the liver. In
spleen, marked deposits thickened the basement membranes of blood vessels and extended into
the surrounding parenchyma. In addition, there were lesser degrees of amyloidosis in other organs
such as small intestine. Amyloid stained positively with Congo red.
In testis, there was encapsulated unilateral interstitial cell tumor, with multiple foci of necrosis
and hemorrhage. The neoplastic cells were round to polyhedral, with small round hyperchromatic
nuclei and finely vacuolated cytoplasm. Signs of feminization were observed. The cause of
amyloidosis in this study was not conclusively identified.
A 28-year-old, female umbrella cockatoo (Cacatua alba) was evaluated because of lethargy, anorexia, regurgitation, and coelomic swelling of 6 month's duration, which corresponded to cessation of egg laying. Radiographs and ultrasound examination demonstrated extensive deposits of coelomic fat and an enlarged oviduct. Exploratory celiotomy demonstrated copious amounts of firm, nodular fat completely surrounding the gastrointestinal tract, resulting in extensive chronic adhesions between intestinal loops. Free yolk was present in the cranial left coelom, yolk coelomitis was diagnosed, and a salpingohysterectomy was performed. Two days after surgery, the bird stopped passing feces and began regurgitating after eating, and a colonic obstruction was demonstrated via contrast radiography. Euthanasia was elected, and necropsy revealed an obstruction of the distal colon caused by extraluminal compression by adhesions of firm, nodular fat. Histologic examination demonstrated extensive fat necrosis with granulomatous inflammation, characterized by cords of necrotic fat surrounded by multinucleated giant cells and epithelioid macrophages with scattered lymphocytes and plasma cells and rare heterophils. The clinical signs, gross lesions, and histologic lesions are characteristic of massive fat necrosis (lipogranulomatosis) in ruminants and mesenteric panniculitis in humans and companion mammals. This is the first report, to our knowledge, of this disease in psittacine birds.
Avian reproductive disorders are commonly diagnosed in pet birds, backyard flocks, and commercial aviaries. Birds that are diagnosed with reproductive disorders can present with a variety of clinical signs that range from benign disorders to life-threatening emergencies. In many cases there are underlying husbandry and management issues that need to be addressed. This article will address the presenting signs of common reproductive disorders in avian species and the best approaches to determine appropriate diagnostic and treatment plans.
The reproductive organs play a key role in the maintenance of normal homeostasis in psittacine birds. For this reason, sex determination should be part of the baseline data collected on every avian patient. Disorders of the psittacine reproductive tract can have a negative effect on the function of other organ systems in the body. Reproductive organs may be plagued by a multitude of problems ranging from infection and neoplasia to inflammation and idiopathic issues that affect fertility. Detection of reproductive problems may require the use of a variety of modalities. The ability to treat these problems often depends on the presenting complaint as well as the clinical condition of the avian patient. Different reproductive disorders of male and female psittacine birds, with their detection and treatment are discussed in this article.
A 6-year-old cockatiel was diagnosed with egg binding based on clinical signs, physical examination findings, radiographs, and lack of oviposition. Medical management failed to induce oviposition, and surgical salpingotomy was used to remove the egg from the oviduct. Sterile egg yolk peritonitis was diagnosed based on histology. Postoperative management with leuprolide acetate and husbandary changes successfully prevented egg production for at least 2.5 months after the event.
A 6 years old cockatiel that laid three eggs in two consecutive days was admitted to the clinic with the complaint of bleeding from the cloaca generate this case. A necrotic tissue that was hanging out and shattered by the cockatiel was noticed in the examination. The prolapsed tissue was determined as uterus (shell gland). The necrotic part of the uterus was excised and it was replaced to normal position. The cloacal opening was sutured. For postoperative care an antibiotic was prescribed for a week. At the last examination one week after the operation no abnormality was detected in the cockatiel and the sutures at the cloaca were removed. In conclusion, it is indicated that such cases can be treated by operatively.
Four cases of egg-binding in psittacine birds caused by torsion and entrapment of the oviduct by the suspensory apparatus of the oviduct are described. Passage of the egg through the oviduct was prevented by the torsion in all birds. The described cases occurred in birds that had laid many clutches of eggs. Three birds were fed diets with vitamin and mineral supplements; the diet of the fourth bird was unknown. One bird was diagnosed on postmortem examination, two were diagnosed and treated by hysterectomy, and one bird was successfully treated with removal of the egg and correction of the torsion, allowing further clutches of eggs to be laid normally. The topographic anatomy of the oviduct of a psittacine bird, a salmon-crested cockatoo (Cacatua moluccensis), is described and compared with that of chickens (Gallus gallus).
Plasma concentrations of prolactin (PRL), corticosterone (B), and luteinizing hormone (LH) were determined in hourly samples collected over a 24-h period from unrestrained, long-term ovariectomized (OVX) turkey hens maintained in cages in an isolation room on a 14 h light:10 h dark photoperiod. Mean plasma concentrations of all three hormones were found to vary significantly with the time of sampling. Mean plasma PRL levels reached a peak (6.50 ± 1.70 ng/mL, x̄ ± SEM) during the latter half of the photophase, declined to a nadir (5.22 ± 1.20 ng/mL) prior to the onset of darkness, and then rose gradually during the scotophase to reach another peak (8.96 ± 1.80 ng/mL) 1 h prior to lights on. Mean plasma LH levels rose significantly (P<.001) from a nadir of 4.11 + .29 ng/mL prior to lights out to a peak of 4.74 + .34 ng/mL during the dark period.
No evidence of random fluctuations in LH levels was observed in any individual, suggesting that episodic LH release may not occur in OVX turkey hens. Individual patterns of B secretion varied substantially so that, although significant increases and decreases in mean plasma B levels were observed, no clearly defined peaks in mean plasma B levels were identified. Individual secretory profiles revealed that peaks in PRL secretion often coincided with peaks in B secretion, but B peaks were usually more numerous. It is concluded that PRL and LH are secreted in a daily rhythm in the OVX turkey hen, with the highest levels of both hormones occurring during the scotophase.
Experiments were conducted to compare dietary and hormonal techniques for molting broiler breeder hens. In the first experiment,
production dropped to 5% 3 wk after hens were restricted to an intake of one half of their calculated energy requirement (FR).
Egg production levels of hens given a single i.m. injection of the Lupron Depot® formulation of leuprolide acetate (LA) in a dose intended to provide 10 μg/kg BW per d for 30 d dropped to 9.5% whereas production dropped to 33% in hens receiving 5 μg and was unchanged by 2.5 μg. Postmolting fertility and hatchability of eggs from the FR and the 10-μg LA groups were not different.
In the second experiment, postinjection egg production, oviduct weight, and uterus weight were depressed, in a dose-related
manner, when hens received 0, 10, or 22 μg LA/kg per d. In a third experiment, egg production dropped to zero within 2 wk when hens were deprived of feed (FD) or deprived
of feed and light (FD + LR), whereas it reached zero in 4 wk in hens fed only 30 g of wheat shorts per d (FR). Lupron Depot® at a dose intended to deliver 30 μg/kg BW per d, reduced egg production to 9.5% by the 3rd wk. Twenty-eight weeks postmolting, egg production ranged from 84
to 98 eggs per hen in the molted groups and 56 eggs per hen in the unmolted controls. Fertility ranged from 82.1% in the FD
+ LR groups to 69.8% in the unmolted controls, whereas chick production averaged 36, 50, 59, 60, and 68 chicks per hen in
the unmolted controls and in hens molted by LA, FR, FD, or FD + LR, respectively.
Chickens and turkeys are commonly encountered in clinical practice. Although many diseases have been reported in these domestic poultry species, certain diseases are commonly encountered in backyard chickens and turkeys. Bacterial diseases that frequently occur in backyard flocks include pasteurellosis (fowl cholera), mycoplasmosis, bordetellosis (turkey coryza), staphyloccosis, and infection with Escherichia coli. Fungal diseases, including aspergillosis and candidiasis, are usually seen as secondary infections. Viral diseases of importance include Marek's disease, lymphoid leukosis, infectious bronchitis, infectious laryngotracheitis, and pox. Lice and mites are ectoparasites that frequently cause problems, and roundworms and cestodes are commonly encountered endoparasites. Coccidiosis and histomoniasis are protozoal diseases that can cause significant problems in backyard poultry.
The reproductive cycle including onset of sexual maturity in hens is not fully understood, but photoperiod or other seasonal changes may be influencing factors. Several different hormones appear to play a role in the onset of ovulation. Luteinizing hormone stimulates the production of prostaglandins by the ovarian follicles. Prostaglandins may help the follicular stigma to rupture, allowing for ovulation. As the ovum passes through the oviduct, the concentration of parathyroid hormone-related protein increases, which may promote relaxation of the proximal oviducts, and cause an increase in blood flow to the oviduct, allowing for increased calcium transfer to the shell. Contractions of the shell gland occur as the egg enters the shell gland and continue at moderate frequency until just before oviposition, when the rate of contractions doubles. Prostaglandin F2α (PGF2α) causes powerful shell gland contractions but does not relax the uterovaginal sphincter or vagina. In contrast, prostaglandin E2 (PGE2) relaxes the uterovaginal sphincter and vagina in addition to causing shell gland contractions, thus allowing for oviposition. Administration of PGF2α when the uterovaginal sphincter is closed may cause either dilation of the uterovaginal sphincter (from constant pressure by the egg), or shell gland rupture if the sphincter fails to dilate. Therefore, the use of PGF2α to alleviate egg binding is not recommended. The use of PGE2 applied locally to the uterovaginal sphincter, however, is advocated.
Suture material should stimulate minimal tissue reaction in wound healing. Tissue reaction to suture material has been studied in various mammalian species; however, the inflammatory cells of birds may react differently to suture materials than do those of mammals. The tissue reaction to five suture materials placed in the body wall of rock doves (Columba livia) was evaluated histologically. Chromic catgut, polyglactin 910, polydioxanone, monofilament nylon, and monofilament stainless steel sutures were placed in the body wall of rock doves by aseptic technique, such that all sutures were placed in each bird, and each bird served as its own control. The tissue reaction was evaluated at 3, 7, 15, 30, 60, 90, and 120 days after surgery. Chromic catgut caused a marked granulocytic inflammatory response that decreased from day 30 forward. This suture material was still present at the conclusion of the study. Polyglactin 910 produced the most intense inflammatory reaction but was the most rapidly absorbed of the materials we evaluated in this study. Polydioxanone caused minimal tissue reaction and was undergoing degradation at the end of the study. Both monofilament nylon and stainless steel caused minimal tissue reaction. These stiff, nonabsorbable materials were more likely to result in formation of seromas, hematomas, and caseogranulomas than were the absorbable materials. When selecting a suture material, various factors should be taken into consideration, including tissue reaction and absorbability. For closure of body wall incisions where a strong, slowly absorbable material causing little tissue reaction is needed, polydioxanone appears to be the best of the five materials evaluated in this study.
The effects of levonorgestrel and medroxyprogesterone acetate on egg production were studied in Japanese quail. Birds were divided into three groups and injected with a depot form of levonorgestrel, a commercially available formulation of medroxyprogesterone acetate, or a saline control. Daily egg production, daily fecal estrogen concentration, and weekly body weights were monitored 7 days before and 70 days after drug or saline administration. The birds were euthanatized 70 days after treatment. A complete necropsy was done on each bird, and selected tissues were examined histologically. All birds treated with levonorgestrel ceased egg laying by the second day after injection, and the average duration of cessation of egg laying was 67.1 ± 4.06 days. In five of seven birds treated with medroxyprogesterone, the average duration of cessation of egg laying was 5.8 ± 2.3 days. In the remaining two birds, egg laying stopped for an extended time (19 and 49 days). The control birds continued to lay throughout the study. Fecal estrone conjugate profiles for quail treated with levonorgestrel and medroxyprogesterone varied compared with the control birds. Concentrations of fecal estrone conjugate decreased between days 1 and 40 in birds treated with levonorgestrel, varied for the duration of the study in birds treated with medroxyprogesterone, and did not fluctuate in the control birds. Necropsy findings in birds treated with levonorgestrel revealed a retained egg within the oviduct of three birds and a calcified egg within the coelomic cavity of one bird. Results of histologic examination were unremarkable in all birds. These results show that a single dose of repository levonorgestrel is effective in preventing egg laying in healthy, young adult Japanese quail.
The avian lineage evolved from ancestral, oviparous amniotes that include reptiles and the archosaurs (therapod dinosaurs and crocodilians). Oviparity represents the ancestral form of reproduction in all archosaurs, and it is the only form of reproduction utilized by birds. Whereas all modern crocodilians have two functional ovaries, only the left ovary is functional in the majority of avian species. Significantly, avian fossils from two species of an extinct lineage (enantiornithine birds of the Early Cretaceous period) have revealed that these ancestors possessed a single, functional left ovary. This is consistent with the hypothesis that the loss of one ovary to reduce body weight occurred early in avian evolution, perhaps even preceding the capacity for true flight. Interestingly, viviparity has evolved nearly 100 times within the reptilian lineage that includes lizards and snakes; thus, it is unclear why there is no incidence of viviparity within the avian lineage. One line of reasoning is that because extant birds are endothermic and can precisely control the process of egg incubation and embryo development, there may be no thermoregulatory advantage to viviparity in birds.
The purpose of this review is to provide an overview of the avian reproductive system. Attention is given to the neuroendocrine regulation of hypothalamic and pituitary gland hormones as well as the target tissues regulated by these hormones. Emphasis is placed on the dynamics of the system and the effects of alterations resulting from environmental and other influences on the function of the reproductive system. The ovulatory cycle, oviduct, and shell gland are discussed relative to egg formation and the hormonal regulation of this process. Testicular function and the cellular bases for spermatogenesis and steroid production are also discussed.
Noninvasive and continuous real-time monitoring, easy handling, minimal size, high tolerability, and affordable costs make pulse oximetry, which has become widely used in human anesthesia, attractive to avian anesthesia as well. It is the only noninvasive method of estimating the arterial oxygen status. Arterial oxygen saturation and pulse rate are measured photometrically by photoelectric detection of the hemoglobin derivates in a pulsating arterial vessel. In our study, spectralphotometric analyses revealed a different photometric behavior of avian and human hemoglobin, which is expected to result in an underestimation of the actual saturation value in birds. Further, the application was tested clinically in pigeons and parrots. We used two commercially available pulse oximeters, one of which was modified for the first time to allow measurements in birds with high pulse rates. The trend of oxygenation was well recorded, but the saturation values recorded by pulse oximetry did not correlate well (r = .81) with arterial saturation derived from blood gas analyses and calculation. Pulse rate and heart rate correlated very well in both pulse oximeters tested. Although the monitoring by pulse oximetry is accurate and continuous in a calmly lying patient, motion artifacts occurred with the beginning of surgery. Critical incidents, like dysrhythmia or severe blood loss, were marked by fluctuation and discontinuity of the displayed values, which, however, failed to record the actual values. The pulse oximeter was reduced to its alarm function. We conclude that pulse oximetry is not satisfactory for routine use in avian practice because of motion artifact and limited feasibility in critical incidents. To adapt the method to avian patients, an avian calibration curve - which would consider the specific avian photometric behavior of hemoglobin as well as photometric effects of the tissue - and a more useful artifact suppression or an ECG-triggered instrument may be required.
In the domestic hen, the preovulatory follicles are arranged in a hierarchy. The largest (F1) follicle ovulates first, the second largest (F2) follicle ovulates approximately 26 h later, and so on. The nature of this regulation is not known. Inhibin has been implicated in the feedback regulation of FSH in mammals, and bioactive as well as immunoreactive inhibin has been demonstrated in chickens. The present experiments were conducted with two aims: 1) to determine the plasma level of immunoreactive inhibin in response to removal of various numbers of preovulatory follicles and 2) to assess the gonadotropin response to such follicle removal. In experiment 1, the F1 (n = 4), F1 + F2 (n = 5), F1 + F2 + F3 (n = 5), and F1 + F2 + F3 + F4 (n = 4) follicles were removed surgically. Sham-operated animals served as controls. Blood samples were taken at time 0 (prior to surgery) and at 6, 24, and 48 h after surgery. In experiment 2, animals were sham-operated (n = 5) or the F1-F4 (n = 4) or F1-F4 plus small yellow follicles (SYF; n = 5) were removed. Blood samples were removed at time 0 and at 3, 6, and 24 h and at daily intervals until Day 10 after surgery. In both experiments, plasma immunoreactive inhibin was significantly lowered (p < 0.001) and plasma FSH was acutely increased (p < 0.05) by follicle removal. Plasma LH was decreased at some time points after follicle removal.(ABSTRACT TRUNCATED AT 250 WORDS)
Plasma concentrations of oestradiol and LH and steady-state pituitary concentrations of the mRNAs encoding the LH β and α subunits in the gland were measured at intervals of 1 month for 5 months in female chickens. In addition, feedback regulation by oestradiol of concentrations of mRNAs encoding these LH subunits was studied in ovariectomized young (3-week-old) and adult hens. Concentrations of the mRNAs encoding the LH β and α subunits increased significantly before sexual maturity and the changes were highly correlated with increases in plasma and pituitary concentrations of LH. Ovariectomy significantly reduced circulating plasma concentrations of oestradiol but increased pituitary concentrations of mRNAs encoding LH β and α subunits and pituitary and plasma concentrations of LH in adult laying hens. In addition, in 3-week-old chickens, ovariectomy induced an increase in plasma and pituitary gland concentrations of LH. This ovariectomy-induced mRNA expression and tissue and plasma increases of LH were prevented by oestradiol replacement. These data suggest that a negative feedback mechanism by ovarian oestradiol inhibits LH release from the pituitary and pituitary LH biosynthesis in chickens.
The right ovary and oviduct are present in embryonic stages of all birds, but the distribution of primordial germ cells to the ovaries of the chicken becomes asymmetrical by day 4 of incubation, and by day 10 regression of the right oviduct begins. The reproductive system of birds (Galliformes) consists of a single left ovary and its oviduct, although on occasion a functional right ovary and oviduct may be present. Among the falconiformes and in the brown kiwi, both left and right gonads and associated oviducts are commonly functional, although the ovaries may be asymmetrical in size; in sparrows and pigeons, about 5% of specimens have two developed ovaries (see Romanoff and Romanoff, 1949; Kinsky, 1971).
Chronic and excessive egg laying is a frequent clinical syndrome in pet birds that can result in reproductive, nutritional, or behavioral pathology. Environmental manipulations to suppress ovarian activity are not always successful, and surgical intervention may involve serious risk. Tamoxifen, an estrogen blocker used to treat women with breast cancer, has been suggested as a chemical method of blocking the hen's reproductive cycle. In this study, 20 budgerigars (Melopsittacus undulatus) of various ages, presumed to be female but not actively laying eggs, were treated with tamoxifen for 38–46 weeks. Adverse effects analogous to those reported in humans were not observed; these included regurgitation, weight loss, loss of appetite, decreased activity, feather changes (alopecia), lameness or wing drooping (bone pain), abdominal distention, and radiographic changes in bone density. In budgerigars treated with tamoxifen, the packed cell volume, total serum calcium concentration, and total protein concentration remained relatively constant throughout the study. Leukopenia was the most significant adverse effect observed in treated birds. When treatment was discontinued, white blood cell counts returned to reference ranges in most birds. Antiestrogenic effects of tamoxifen were suggested by a change in cere color from white or brown to blue in birds during treatment. If tamoxifen is used in budgerigars, birds should be screened for subclinical infectious disease before treatment begins, and white blood cell counts should be monitored.
It is common for veterinarians who specialize in small animals and species to be presented with pet bird patients for procedures that require general anesthesia, including complete physical examination, venipuncture, diagnostic workup, or medical and surgical treatments. The basic principles of anesthetic management that govern mammalian anesthesia also apply to birds, although specific anatomic and physiological differences must be considered. The goal of this article is to present a clinically applicable approach to pet bird anesthesia, including preanesthetic considerations, physical restraint, induction agents, anesthetic maintenance, supportive measures, anesthetic recovery, and management of anesthetic complications.
As veterinarians, we are indeed fortunate to be able to work with animals from a variety of taxonomic groups. The anatomic and physiological differences among animal taxa affect how we manage these animals. Anatomic differences are obvious, but it is the subtle differences in physiological function that challenge our knowledge and experience. The unique anatomy and physiology of birds enable some to fly at altitudes of 32,000 feet without supplemental oxygen, to dive underwater for many minutes, and to live at environmental extremes from the frozen deserts of the polar caps, to the heat and humidity of the tropics, to the dry heat of the earth's deserts. This article reviews unique anatomic and physiological features of the avian respiratory system, and how they impact on anesthetic management.
This article reviews the following common problems encountered in avian obstetrical medicine: egg binding, dystocia, prolapsed oviduct, egg yolk peritonitis, chronic egg laying, oviduct impaction, oophoritis, salpingitis, metritis, ectopic eggs, cystic hyperplasia of the oviduct, neoplasia, and cloacal pathology. Each section defines a problem and discusses its proposed etiologies, clinical signs, and pertinent diagnostics and treatment options.
An analysis is provided of reproductive disorders encountered at necropsy of 1666 adult, female birds excluding poultry. The results are compared with other accounts of these disorders in non-domesticated species and poultry. At least 650 different species were examined, belonging to 24 of the 27 avian orders. All were non-domesticated birds, with the exception of 133 budgerigars, 48 canaries and 4 pigeons. Reproductive disorders were found in 148 (8.9%) representing 88 different species in six orders. There was no conclusive evidence of species susceptibility. Some individuals were affected with more than one type of disorder, the most prevalent being obstruction of the oviduct and ectopic ovulation; in each case 28.6% of 161 disorders. Less common disorders were oophoropathies (16.8%), salpingitis without apparent obstruction (10.6%), neoplasia (4.3%), ruptured oviduct (3.1%) and miscellaneous disorders (8.0%). Domestic poultry bred for egg production are probably more susceptible to reproductive disorders than non-domesticated species. In the latter birds predisposing causes include senility and bacterial infections, but many more are probably involved.
The technique of laparoscopy was adapted and utilized in zoological medicine for various mammals, birds, and reptiles for reproductive and diagnostic studies as well as clinically related research. It was concluded that since anesthesia was routinely required for most manipulative procedures in zoo animals, and since laparoscopy adds little additional risk, the use of this technique provides an additional diagnostic aid when indicated. Laparoscopy was found to be effective for evaluating reproductive status, particularly ovarian anatomy and function, direct visual biopsy of internal organs, sex determination in selected birds, and as a surgical means of fertility control.
A mature cockatiel was presented to the teaching hospital with acute, severe dyspnea and a markedly enlarged abdomen. The bird died 2 hours after admission and was necropsied. A 3-cm egg yolk was present in the abdominal cavity and caused cranial displacement of the abdominal viscera. Death occurred acutely and was probably due to severe respiratory distress. /// Una periquita adulta fue llevada al hospital veterinario con una disnea aguda y con el abdómen marcadamente aumentado de tamaño. El ave murió dos horas después de la admisión. A la necropsia se le encontró en la cavidad abdominal el saco vitelino de un tamaño de 3 cm que le causó el desplazamiento craneal de todas las vísceras. La muerte ocurrió en forma aguda y probablemente debido al comprometimiento respiratorio severo.
Testicular regrowths were observed in 10 of 21 tom turkeys between 28 and 32 weeks old, which was between 19 and 23 weeks after surgical caponization at 9 weeks of age. Regrowths were not observed in younger caponized toms. Two types of histologic patterns that differed from the normal pattern were observed in these regrowths. The first pattern was observed in seven regrowths and was characterized by a higher density of seminiferous tubules and more interstitial cells. The second pattern was seen in three regrowths and was characterized by extensive intertubular fibrosis, tubular detachment, and an increased number of interstitial cells. No correlation was found between the presence of these regrowths and plasma testosterone levels. The interstitial cell hyperplasia in all regrowths possibly was related to a diminished negative feedback by the endogenous testosterone on the release of luteinizing hormone from the pituitary. The appearance of regrowths at this age probably was related to the onset of normal physiological puberty.
Testes of Pekin ducks were macerated following injection with plastic at the period of maximal spermatogenesis which occurs during spring. The right and left A. testicularis arise from the A. renalis cranialis. The right testis is additionally supplied by an irregularly occurring A. testicularis accessoria. After penetrating the testicular capsule the arteries run to the centre of the testis and terminate as branching Aa. radiatae centrifugales. The seminiferous tubules are surrounded by intertubular and peritubular capillaries forming a rope-ladder-like system. Venules and veins run peripherally to enter the vein converge into the testicular hilus, and unite to form 2 Vv. testiculares which empty into the V. cava caudalis. Regulation of testicular blood supply is achieved by throttle devices depending on the avian seasonal cycle. The coiled and step-like course of the vessels results in a sufficient contact between blood and seminiferous tubules. Testicular veins surrounding the arteries might be an equivalent of the steroid transfer mechanism in the mammalian spermatic cord.
A 10-year-old female cockatiel in a thin and depressed condition and with a 1 X 2-cm soft abdominal swelling was hospitalized. Radiography revealed a well-circumscribed mass containing punctate areas of mineralization, displacing the gizzard cranially in the caudodorsal portion of the abdomen. There was bilateral, symmetric, generalized, increased medullary opacity of the radius, ulna, carpometacarpus, femur, tibiotarsus, and tarsometatarsus. These findings were compatible with polyostotic hyperostosis secondary to an estrogen-secreting tumor. Euthanasia and necropsy were requested. A small area of neoplastic cells in the oviduct was identified histologically, but most of the tissue mass consisted of necrotic cellular debris. There was no metastasis. Sagittal secretions of decalcified radiopaque bones revealed up to 60% filling of medullary cavities with bone spicules. Although clinical and radiographic findings were compatible with an estrogen-secreting tumor, osteopetrosis, metastatic neoplasia, hypertrophic osteopathy, and metabolic bone disease were included in the initial differential diagnosis. The absence of metastasis and the confinement of the tumor within the oviduct would have made surgical removal a possible approach to treatment.
The effect of ovariectomy (OVX) on plasma concentrations of prolactin (PRL) and luteinizing hormone (LH) in incubating turkey hens was studied. Neither the sham-operated nor the OVX hens exhibited any change in the pattern of incubation behavior as a result of the surgery. Plasma concentrations of estradiol decreased to less than approximately 3 pg/ml by 2 days after surgery in the OVX hens. There were no significant differences in plasma levels of PRL between the sham-operated and OVX hens throughout the study. The concentration of PRL did not change in either the sham-operated or OVX hens and was maintained at high levels after surgery and during incubation of the eggs. By 2 days after hens were placed into cages, plasma levels of PRL significantly decreased and were maintained at low levels in both groups. The concentration of LH did not change in either group during the two wk after surgery when the hens were incubating eggs. After the hens were placed into cages, the concentration of LH increased in the OVX hens and was maintained at significantly higher levels than in the sham-operated hens. By contrast, the concentration of LH increased within 4 days after OVX of out-of-lay but nonincubating hens. The delay in the postcastration increase in plasma level of LH in the OVX hens was not associated with anorexia of incubating hens, since plasma levels of LH were not affected by force-feeding unless plasma levels of PRI were suppressed by nest deprivation.(ABSTRACT TRUNCATED AT 250 WORDS)
Present available information regarding ovarian tumors in hens is incomplete in most aspects, and this lack of knowledge hampers use of hens as models for study of ovarian cancer. A study of 466 hens ranging from 2 to 7 years of age and covering a period of more than 3 years has provided much needed information relative to reproductive tract neoplasia. On the basis of this study, it is apparent that hens have a high rate of ovarian tumors, but that such tumors are uncommon in hens less than 2 years of age. Adenocarcinomas with a high degree of morphologic variability are the most common ovarian tumors in hens. Hormonal imbalance does not appear to be a factor in the development of these adenocarcinomas. Steroidogenic and morphologically distinctive granulosa cell tumors originating from follicles in atrophic ovaries represent another common ovarian tumor type. Unique to the hen are oviductal adenocarcinomas. These tumors arise from the albumin-secreting glands of the oviduct, occur with relatively high frequency, and must be differentiated from ovarian adenocarcinomas.
Testicles were collected from 33 male Japanese quails older than 3 years. Three of these quails (9.1%) had one or two large neoplastic testicles. These testicles were 2-5 times normal size, round, and firm, with cystic spaces of various sizes. Microscopically, there was marked intratubular Sertoli cell proliferation and various-sized cystic spaces filled with an eosinophilic vacuolated fluid. Microscopic changes in all neoplastic testicles were diagnostic for Sertoli cell tumors. /// Se tomaron testículos de 33 codornices Japoneses de más de 3 años de edad. Tres codornices (9.1%) tuvieron uno o dos testículos neoplásicos. Estos testículos eran 2-5 veces el tamaño normal, redondos y firmes; mostrando espacios quísticos de tamaño variado. Microscópicamente se encontró una marcada proliferación intralobular en las células Sertoli y varios espacios quísticos llenos con líquido vacuolado eosinofilico. Los cambios microscópicos en todos los testículos neoplásicos fueron diagnosticados como tumores de las células Sertoli.
Causes of sickness and death in approximately 30,000 chickens in 5 meat breeder flocks were investigated between May 1979 and April 1980. Approximately 23% of disease was due to neoplasms; 81% of these were Marek's disease despite vaccination against this infection. Other frequent diagnoses included cellulitis (15%), respiratory disease (14%), lesions of the reproductive tract (11%) and tenosynovitis/arthritis (9%). Antibodies to Mycoplasma gallisepticium, avian adenovirus, infectious bursal disease virus and reticuloendotheliosis virus were present in all flocks. Antibody to Newcastle disease virus (NDV) was found in 2 flocks but titres were not considered protective against a virulent NDV challenge. Antibody to egg drop syndrome 1976 virus was found in 2 flocks comprised of the same breed of bird.
Egg binding most often affects budgerigars, cockatiels, finches and canaries. Causes include oversized or malpositioned eggs, lack of exercise, nesting too early or late, excessive egg laying, uterine damage or infection, obesity, malnutrition, sudden drops in ambient temperature and genetic factors. Clinical signs are perching unsteadily with ruffled feathers and half-closed eyelids, frequent tail-wagging or straining, swelling over the tail base, and sitting on the cage bottom. Diagnosis is by physical examination and radiography. Treatment may involve increasing the ambient temperature to 85-90 F, lubricating the vent, IM injections of Ca solution and/or oxytocin, egg aspiration and laparotomy.
The prevalence of salpingitis in broilers at slaughter seems to be rather constant, constituting 0.02--0.03% of the broilers slaughtered (Table I & Figure 1). Profuse growth of Escherichia coli in pure culture was obtained from the salpinx of all 123 investigated carcasses with chronic salpingitis. Primary blood agar plates examined showed a pure culture as to O-group as well. Of 22 different O-groups demonstrated, 01, 02, 07 and 053 were most prevalent, constituting 47% of the strains (Table III). Salmonella spp. were not demonstrated. Etiology, pathogenesis and possible food hygienic consequences are discussed in the light of the present findings.
A readily palpable abdominal mass in a 10-year-old pigeon (Columba livia) was diagnosed as seminoma on histologic examination.
Takahashi T, Kawashima M, Kamiyoshi M, Tanaka K. Arginine vasotocin receptor binding in the hen uterus (shell gland) before and after oviposition. Eur J Endocrinol 1994;130:366–72. ISSN 0804–4643
The binding affinity and capacity of arginine vasotocin (AVT) receptor in the hen uterus changed during a period before and after oviposition. Three hours before oviposition, the binding capacity of the AVT receptor increased. An injection of prostaglandin (PG) F 2α caused an increase in the AVT receptor B max in the uterus, and indomethacin blocked the normal rise in the AVT receptor B max and PGF content prior to oviposition. However, just prior to oviposition, the binding affinity increased with a decrease in the binding capacity. A progesterone injection caused an increase in binding affinity and a decrease in binding capacity of the AVT receptor. The specific binding of the progesterone receptor in the uterus increased 2 h before oviposition and remained high until oviposition. Serum AVT levels increased at oviposition. An injection of AVT caused an increase in the affinity of the AVT receptor with a decrease in the capacity. The change in the affinity and capacity of AVT receptor at oviposition may result from the action of progesterone via increased progesterone receptor binding, and the action of AVT on its own receptors.
Michiharu Kamiyoshi, Department of Animal Production and Utilization Sciences, The United Graduate School of Agricultural Science, Gifu University, 1-1 Yanagido, Gifu 501-11, Japan