The Urinary and Osmoregulatory Systems of Birds.

The avian kidney contains both cortical or reptilian and medullary or mammalian nephrons. The kidney filters up to 11 times the total body water daily. Approximately 95% of this volume is reabsorbed by tubular reabsorption, which likely results from a change in the rate of filtration and/or the rate of reabsorption. These changes can result because of the antidiuretic hormone arginine vasotocin. The urinary concentrating ability generally varies inversely with body mass; however, birds can concentrate their urine, often at 2 to 3 times the osmolality of plasma. Further concentration of urine may occur by retroperistalsis.

Avian Ganglioneuritis in Clinical Practice.

Avian ganglioneuritis (AG) comprises one of the most intricate pathologies in avian medicine and is researched worldwide. Avian bornavirus (ABV) has been shown to be a causative agent of proventricular dilatation disease in birds. The avian Bornaviridae represent a genetically diverse group of viruses that are widely distributed in captive and wild populations around the world. ABV and other infective agents are implicated as a cause of the autoimmune pathology that leads to AG, similar to human Guillain Barrè syndrome. Management of affected birds is beneficial and currently centered at reducing neurologic inflammation, managing secondary complications, and providing nutritional support.

Clinical avian nutrition.

Psittacine birds eat plant-based foods. Birds in the wild seem to be able to balance their energy needs, amino acids, and calcium. Companion birds in captivity do not do as well when self-selecting, and balanced diets are needed to improve their general health. A nutritional history is important to determine whether the avian patient is in balance nutritionally. Understanding the various sources of the fat-soluble vitamins, calcium, and protein will help guide clients to provide nutritious foods for their birds. Owners need to learn to use foraging as a major source of their bird's diet and techniques.

Avian respiratory distress: etiology, diagnosis, and treatment.

Respiratory distress is usually a life-threatening emergency in any species and this is particularly important in avian species because of their unique anatomy and physiology. In the emergency room, observation of breathing patterns, respiratory sounds, and a brief physical examination are the most important tools for the diagnosis and treatment of respiratory distress in avian patients. These tools will help the clinician localize the lesion. This discussion focuses on the 5 anatomic divisions of the respiratory system and provides clinically important anatomic and physiologic principles and diagnosis and treatment protocols for the common diseases occurring in each part.

Rabbit respiratory system: clinical anatomy, physiology and disease.

Rabbits are obligate nose breathers due to their epiglottis positioned rostrally to the soft palate. Any obstruction within the nasal cavity will produce a respiratory wheeze with increased respiratory effort. Respiratory diseases are a major cause of morbidity and mortality in rabbits. This article focuses on these diseases and their causative pathogens.

Ferret respiratory system: clinical anatomy, physiology, and disease.

The upper and lower respiratory tracts of ferrets have several similarities to humans, and therefore have been used as a research model for respiratory function. This article describes the clinical anatomy and physiology, and common respiratory diseases of the ferret.

Avian neuroanatomy revisited: from clinical principles to avian cognition.

Several significant advances in understanding brain-behavior development have made a critical contribution to clinical assessment of companion birds. First, psychobiological health and its dysfunctions now are understood as the product of nature and nurture and therefore exquisitely sensitive to stressors effected by altered socio-ecological conditions within and across generations. Second, discoveries associated with avian brain evolution and ethology show that emotional and cognitive capacities of birds are comparable to mammals. This article presents an overview of these new perspectives and, following, discusses specific, clinically relevant anatomy of the avian central nervous system. By understanding the location of these tracts and their function and the location of the cranial nerves and their nuclei in the brain stem, the clinician can understand and perform the neurological examination, better interpret findings, and localize lesions.

Antifungal drug therapy in avian species.

This article reviews current literature regarding antifungal drugs available for veterinary and human use and those that are in clinical trials. Drugs include the polyenes, amphotericin B and nystatin; flucytosine; and the first generation triazoles. Antifungal agents generally not used in avian medicine or which are being analyzed in clinical trials in people include lipid formulations of amphotericin B and nystatin, voriconazole, echinocandins, and the allylamines. Information about the pharmacology of the triazoles in people is contrasted with known information for these drugs in birds. Extrapolation of efficacy to avian species also is discussed.

Avian reproductive anatomy, physiology and endocrinology.

Although many environmental cues influence reproductive activity, the seasonal breeder responds most strongly to long day length. THE MALE BIRD: Testicular interstitial cells secrete testosterone, which influences reproductive behavior such as territorial aggression and song. Other changes observed in seasonal breeders include testicular hypertrophy and enlargement of the ductus deferens and seminal glomus. THE FEMALE BIRD: Early changes associated with rising estrogen levels in the hen include osteomyelosclerosis and hypercalcemia. Ovulation is then induced by LH, which is followed by eggshell calcification, which is under the control of progesterone. Sources of calcium for shell production include intestinal absorption from the diet, renal control of calcium levels, and mobilization of bone calcium stores. During oviposition, PGF2 alpha and vasotocin stimulate powerful uterine contractions [32] in the presence of calcium. Incubation is associated with falling LH levels and rising prolactin levels. If the hen actually enters reproductive quiescence at this time, then molt will follow. Molt is associated with the total regression of the reproductive tract.

Clinical considerations of the thoracic limb.

The avian skeleton is significantly different from the mammalian skeleton, and these differences are important when providing fracture repair and postoperative care for the avian patient. Successful repair depends on an understanding of fracture management and healing and of the anatomical, physiologic, and behavioral concerns of avian patients. Having knowledge of fracture repair without an understanding of the unique needs of avian patients' results in a disappointing treatment response.