The anatomy and physiology of the avian endocrine system.

The endocrine system of birds is comparable to that of mammals, although there are many unique aspects to consider when studying the anatomy, physiology, and biochemistry. Avian endocrinology is a field of veterinary medicine that is unfamiliar to many practitioners; however, it is important to have a comprehensive understanding when evaluating companion birds in clinical practice. This article covers the anatomy and physiology of the normal avian, and readers are referred to other articles for a more detailed explanation of altered physiology and pathology.     

Avian renal disease: pathogenesis, diagnosis, and therapy.

Avian renal diseases are common in practice but are often undetected or misdiagnosed. Polyuria can be interpreted as diarrhea leading to inappropriate investigation and therapy. The avian urinary system differs from the mammalian. This article explains the anatomy and physiology of the avian kidney and focuses on the diagnosis of renal disorders. In particular, blood chemistry, urinalysis, radiography, urography, ultrasonography, computed tomography, and endoscopy (including biopsy) are explained and illustrated. Specific avian renal disorders and treatment possibilities are discussed.     

Arterial Catheterization,Interpretation, and Treatment of Arterial Blood Pressures and Blood Gases in Birds

Blood pressure monitoring of patients has become increasingly common in companion animal veterinary hospitals, especially during anesthesia, surgical procedures, critical care, and general health assessments. Determining an animal’s blood pressure has become a standard part of the routine diagnostic evaluation for monitoring hypertension in geriatric patients or patients affected with renal insufficiency, cardiac disease, vision loss, or endocrine disorders. To increase the standard of care in exotic and zoological medicine, new diagnostic techniques must be identified and implemented. Blood pressure measurements in avian species are more challenging because only direct blood pressure techniques have been reported to be accurate. Arterial catheterization and interpretation can be daunting without the knowledge of avian physiology and anatomy; however, techniques for placing arterial catheters are not difficult once clinicians have gained sufficient experience. This article describes the techniques, anatomy, and appropriate interpretation of blood pressure results obtained through arterial catheterization in birds.     

Update on neuroendocrine regulation and medical intervention of reproduction in birds.

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.     

The avian pancreas in health and disease.

The avian endocrine pancreas shares some similarities with mammals but also some clinically relevant differences in anatomy and physiology. Diabetes mellitus, an uncommon disease of pet birds, is a challenging condition because of lack of knowledge of the exact pathophysiology and responses to insulin therapy. This article reviews the anatomy and physiology of the avian pancreas and describes the etiology, diagnosis, and treatment of diabetes mellitus in pet birds.     

Reproductive medicine of rabbits and rodents.

The small animal practitioner is likely to be called upon to help nontraditional pets such as rabbits, rodents, and ferrets. The more information veterinarians have regarding normal anatomy, physiology, reproduction, medicine, anesthesia, and surgery of these unusual pets, the more likely they will be able to help their owners. This article presents an overview of routine and emergency reproductive concerns that the small animal practitioner may face when presented with nontraditional mammalian patients.     

Some considerations when nursing birds in veterinary premises

This paper indicates the need for, and the benefits to be gained by, better standards of avian nursing. The subject is approached by a discussion of the behaviour of birds in general and suggests ways in which stress in the hospitalized bird can be reduced to the minimum. The dangers of young birds becoming imprinted are emphasized. The contrasts between mammalian and avian anatomy, particularly of the respiratory and renal systems, are considered together with the implications when nursing birds. There is a discussion of the avian metabolic rate, the nutrition of sick birds, and some indications for physiotherapy in birds are mentioned.     

Adrenal steroid metabolism in birds: anatomy, physiology, and clinical considerations.

The hypothalamo-pituitary-adrenal system in birds is anatomically and functionally different from that in mammals. The adrenal gland structure and corticosteroid hormone physiology of birds will be reviewed. The anatomy and physiology sections of this article will be important for better understanding the pathogenesis, diagnosis, and possible treatment of primary or secondary adrenal gland disease. Causes of hyper- and hypoadrenocorticism in birds also will be reviewed. The article will conclude with current indications and complications to the clinical use of glucocorticoids in birds.     

Resistance to Serum Complement,iss, and Virulence of Avian Escherichia coli

Control of avian colibacillosis is hampered by lack of easily identifiable markers for virulent Escherichia coli. Resistance to serum complement appears to be a widespread trait of virulent avian E. coli, suggesting that bacterial factors promoting survival in serum may be useful in discriminating between virulent and avirulent isolates. Such distinguishing factors may prove useful in diagnostic protocols or as targets in future colibacillosis control protocols. Interestingly, the factors responsible for resistance to complement differ in the E. coli isolated from mammalian and avian hosts, which may reflect differences in the nature of avian and mammalian colibacillosis. In some cases, genetic determinants for serum complement resistance in avian E. coli are found on aerobactin- or Colicin V-encoding plasmids. One such gene, iss, first described for its role in the serum resistance associated with a ColV plasmid from a human E. coli isolate, occurs much more frequently in isolates from birds with colibacillosis than in faecal isolates from healthy birds. Efforts to identify the genomic location of iss in a single, virulent avian E. coli isolate have revealed that it occurs in association with several purported virulence genes, all linked to a large conjugative R plasmid. At this time, it is not known whether iss merely marks the presence of a larger pathogenicity unit or is itself a contributor to virulence. Nevertheless, the presence of the complement-resistance determinant, iss, may be a marker of virulent avian E. coli exploitable in controlling avian colibacillosis.     

中国基干鸟类综述

"基于鸟类(basal birds)"为一种类数量相对较少的化石鸟类,基干鸟类较另一鸟类群--"鸟胸类(Ornithothoraces)"原始;鸟胸类(包括现生鸟类和反鸟类)为一类种类数量很大、具有同一祖先、且来源于基干鸟类的鸟类群.在过去的15年里,共有产自中国的8个属、12个有效种基干鸟类发表,而产自的德国的始祖鸟为唯一的非中国产基干鸟类;当然,孔子鸟化石也发现于朝鲜.本文对产自中国的基干鸟类的形态学、系统发生和生态学进行了简单的综述.中国的化石材料对科学地了解鸟类的早期演化具有重要意义,揭示了基干鸟类个体相对较大、形态特征和生态环境变异也相对较大等特点.尽管有些明显的不确定因素的存在(例如热河鸟、会鸟和中鸟的相对系统关系存有争议),但是由于中国化石材料的存在,鸟类早期演化的真实场景已经愈加清晰.     

Overview of the avian immune system.

The avian immune system operates on the same general principles as the mammalian immune system. Antigenic stimulation initiates an immune response that involves cellular cooperation most notably between macrophages, B lymphocytes and T lymphocytes. Macrophages process the antigen and present the antigen to the lymphocytes. B lymphocytes, the principal cells that mediate humoral immunity, transform into plasma cells and produce antibodies. T lymphocytes, most important for cellular immunity, differentiate into functionally diverse subpopulations. The subpopulations of avian T cells have been identified with monoclonal reagents and appear to be similar to those of mammalian T cells. Lymphokines, the soluble products secreted by immune cells, mediate the functions of these cells. Studies on avian lymphokines have lagged behind those on mammalian lymphokines because the genes coding for avian lymphokines have not been cloned. The avian lymphokines studied thus far appear to function along the same lines as the mammalian lymphokines. The immune response in birds is highly regulated and breakdown in regulation often results in immunodepression.     

Avian defensins

Modulation of defensin expression may be one way to improve animal health and to reduce zoonotic diseases. Defensins are small, cationic, and amphipathic cysteine-rich antibiotic peptides found in plants, insects, mammals and birds. Whereas alpha- and theta-defensins appear to be absent in birds, several beta-defensins have been isolated from avian heterophils. In addition, beta-defensins were found to be constitutively or inducibly expressed at mucosal surfaces of the respiratory, intestinal and urogenital tracts. In this review the current knowledge of the defensin repertoire of birds, their tissue-specific expression, regulation and corresponding biological functions are described.     

Avian Vision: A Review of Form and Function with Special Consideration to Birds of Prey

More so than any other terrestrial vertebrate, birds rely most heavily on their ability to assess their visual environment. High visual acuity is not only necessary to find and acquire food, but also to navigate surroundings, to identify conspecifics and potential mates, and to quickly identify and escape from predators. This article aims to help the reader understand how birds, particularly birds of prey, see by reviewing pertinent anatomy and physiology of the eye, color vision, visual fields, visual acuity, accommodation, and flicker-fusion frequency. For more information on specific disease conditions of the avian eye, the reader is encouraged to review any number of avian medical and surgical texts.     

Laparoscopy in zoological medicine.

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.     

Th1/Th2 polarization by viral and helminth infection in birds

Mammals developed an immune system able to functionally polarize into so-called type 1 or type 2 immune pathways, to resolve infections with intracellular and extracellular pathogens, respectively. In the well-studied avian immune system of the chicken, however, no evidence for polarized immunity could be found, as yet. To investigate whether these two major arms of mammalian immunity, regulated by a T helper (Th)1/Th2 cytokine balance, evolved similarly in birds, chickens were exposed to a prevalent intracellular (viral) or extracellular (helminth) infection. By using semi-quantitative RT-PCR analysis we provide evidence that polarization of Th1/Th2 type immunity extends beyond mammalian species, and, therefore, has been evolutionary conserved for more than 300 million years, when the lineages of mammalian and avian vertebrates are assumed to have segregated.     

The anatomy, physiology, and diseases of the avian proventriculus and ventriculus.

Diseases affecting the proventriculus and ventriculus often present with similar clinical signs. It is important for the avian practitioner to be familiar with these diseases, their prevalence, and the species most commonly affected to judiciously prioritize the appropriate diagnostic techniques. A basic understanding of the anatomy and physiology of the proventriculus and ventriculus is useful in integrating the pathophysiology and clinical signs associated with variable disease processes. It is also essential to evaluate radiographs and endoscopic images, perform diagnostic techniques, make a diagnosis, and provide appropriate therapy.     

Primordial germ cell-mediated transgenesis and genome editing in birds

Transgenesis and genome editing in birds are based on a unique germline transmission system using primordial germ cells(PGCs), which is quite different from the mammalian transgenic and genome editing system. PGCs are progenitor cells of gametes that can deliver genetic information to the next generation. Since avian PGCs were first discovered in nineteenth century, there have been numerous efforts to reveal their origin, specification, and unique migration pattern, and to improve germline transmission efficiency. Recent advances in the isolation and in vitro culture of avian PGCs with genetic manipulation and genome editing tools enable the development of valuable avian models that were unavailable before. However, many challenges remain in the production of transgenic and genome-edited birds,including the precise control of germline transmission, introduction of exogenous genes, and genome editing in PGCs.Therefore, establishing reliable germline-competent PGCs and applying precise genome editing systems are critical current issues in the production of avian models. Here, we introduce a historical overview of avian PGCs and their application, including improved techniques and methodologies in the production of transgenic and genome-edited birds, and we discuss the future potential applications of transgenic and genome-edited birds to provide opportunities and benefits for humans.     

中草药防治母牛不孕症及其作用机理

养牛业作为农业产业之一,肉、奶等产品在市场上的需求不断提升,但在养殖过程母牛患上生殖系统疾病,该病可引发发情期紊乱等疾病,如不有效治疗会严重影响母牛正常繁殖,养殖场效益受到影响。母牛生殖系统疾病治疗需根据临床诊断采取合理的方案进行,中草药治疗该病在临床上效果明显,本文通过采用中药对母牛生殖系统疾病进行,并阐述相关的作用机理,以供同行参考。