The respiratory system influences flight mechanics in soaring birds.

The subpectoral diverticulum (SPD) is an extension of the respiratory system in birds that is located between the primary muscles responsible for flapping the wing1,2. Here we survey the pulmonary apparatus in 68 avian species, and show that the SPD was present in virtually all of the soaring taxa investigated but absent in non-soarers. We find that this structure evolved independently with soaring flight at least seven times, which indicates that the diverticulum might have a functional and adaptive relationship with this flight style. Using the soaring hawks Buteo jamaicensis and Buteo swainsoni as models, we show that the SPD is not integral for ventilation, that an inflated SPD can increase the moment arm of cranial parts of the pectoralis, and that pectoralis muscle fascicles are significantly shorter in soaring hawks than in non-soaring birds. This coupling of an SPD-mediated increase in pectoralis leverage with force-specialized muscle architecture produces a pneumatic system that is adapted for the isometric contractile conditions expected in soaring flight. The discovery of a mechanical role for the respiratory system in avian locomotion underscores the functional complexity and heterogeneity of this organ system, and suggests that pulmonary diverticula are likely to have other undiscovered secondary functions. These data provide a mechanistic explanation for the repeated appearance of the SPD in soaring lineages and show that the respiratory system can be co-opted to provide biomechanical solutions to the challenges of flight and thereby influence the evolution of avian volancy.

Grey parrot (Psittacus erithacus) beak papillae and nerves identified using novel 2-D and 3-D imaging modalities.

OBJECTIVE: The avian beak is a complex organ containing bone, neurovascular tissue, and keratinized covering (rhamphotheca). Nerve-rich papillae extend through bone into rhamphotheca providing sensory input from the beak tip. Beak trimming is a common procedure in avian species and is used for corrective, cosmetic, and behavioral modification purposes. Yet, practitioners are not well versed in complete beak anatomy, and therefore, beak trimming often disregards neurovasculature, injuring the patient and hampering recovery. Here, using comprehensive anatomical description, we aim to provide recommendations on how to safely perform beak trimming without damaging underlying sensory papillae. ANIMALS: Here, we evaluated beaks of 2 deceased grey parrots (Psittacus erithacus). PROCEDURES: In one, we used a novel stain and microcomputed tomography to visualize papillae in the upper and lower beaks. In a second, we hand isolated the upper and lower beak dermal papillae and used high-resolution photography plus traditional paraffin histology. RESULTS: Papillae and their nerves were easily identified in these 2- and 3-dimensional approaches. This allowed us to determine the approximate lengths of papillae within the upper and lower beak. CLINICAL RELEVANCE: Based on these findings, the authors recommend lateral radiographs of the bird's head and beak to identify the location of the underlying bone relative to the overlying rhamphotheca before performing beak trims. Specifically in grey parrots, the authors recommend the upper and lower beak should not be trimmed closer than 8 to 10 mm from the underlying bone. Further work is needed to support these recommendations and provide guidelines for other species.

Medical and Surgical Management of Phaeohyphomycosis in a Kea (Nestor notabilis).

A 2.5-year-old female kea (Nestor notabilis) weighing 711 g was presented for acute lethargy, pelvic limb paraparesis, and decreased appetite. Results from a complete blood count revealed a leukocytosis (67540 cells/µL [reference interval 4200 - 37880 cells/µL]). Radiographic images revealed a mass effect within the mid coelom. The patient was provided supportive care that included antifungal medication (voriconazole 15 mg/kg PO q12h x 6 months and 10 days) and antibiotic therapy (enrofloxacin 20 mg/kg PO q12h x 27 days). A discrete 2.3 × 2.7 × 2.6 cm soft tissue mass adjacent to multiple organs was identified on contrast computed tomographic images (IsoVue 370 at 4 mL/kg IV over 2 minutes). The mass was medial and dorsal to the proventriculus, cranial to the ventriculus, caudal to the liver, and ventral to the cranial renal divisions. The mass had an irregular vascularized wall with a poorly vascularized center. Ten days after initial presentation, exploratory coeliotomy and mass removal via left lateral coeliotomy were performed. Bacterial (aerobic and anaerobic) and fungal cultures were negative. Fourteen days postsurgery, the leukocytosis was resolved. Microscopic review of the submitted tissue mass found multinucleated giant cells, macrophages, and brown fungal hyphae with irregular internal septations and some branching, leading to a diagnosis of phaeohyphomycosis. Panfungal polymerase chain reaction testing and sequencing were unsuccessful at speciation. Treatment with voriconazole was continued until behavioral, hematologic, and computed tomographic assessments indicated resolution of the problem 6 months postsurgery. No recurrence of disease has been reported 20 months following mass removal.

Diagnosis of Seminoma With Metastasis to the Brain and Kidneys in a Moluccan Eclectus (Eclectus roratus) Using Advanced Contrast Based Imaging.

A 20-year-old male Moluccan eclectus (Eclectus roratus) was presented with a history of falling off the perch, ataxia, unilateral blindness, hyporexia, and progressive lethargy. The eclectus was found to have a leukocytosis (52 × 103 cells/µL), characterized by an absolute and relative heterophilia (42.6 × 103 cells/µL and 82%, respectively), relative lymphopenia (18%), elevated bile acids (88 µmol/L), and elevated triglycerides (236 mg/dL). Radiographic images revealed a mass effect within the caudal coelom. After 13 days of outpatient supportive care, the patient was rechecked and had normalized bile acids (<35 µmol/L), static triglycerides (232 mg/ dL), and hyperuricemia (18.6 mg/dL). Computed tomography was performed antemortem with and without iodinated contrast agent, 4 mL/kg IV over 2 minutes, and a mass was found associated with the left kidney. Due to worsening neurologic signs and involvement with surrounding structures, the owner elected euthanasia. Before the postmortem examination, a postmortem intravascular contrast agent was used to provide a more thorough visualization of internal anatomical structures, including left renal vasculature disruption, mass vasculature, caudal coelomic organ displacement, and increased irregular optic chiasm radiodensity. Postmortem, a 4 × 4.1 × 5.1-cm white to tan mass was identified. Histopathology confirmed a seminoma with metastasis to the kidneys and optic chiasm. Seminomas have been described in avian species; however, seminoma metastasis in an eclectus parrot confirmed by histopathology has not been reported, and optic chiasm metastasis of a seminoma has not been described in any avian species. This report describes postmortem computed tomographic angiography of metastatic seminoma in a Moluccan eclectus with metastasis to the optic chiasm.

Functional Adaptations in the Forelimb of the Snow Leopard (Panthera uncia).

The snow leopard (Panthera uncia) is anatomically and physiologically adapted for life in the rocky terrain of alpine zones in Central and South Asia. Panthera uncia is scansorial, and typically hunts solitarily by using overhead ambush of prey, rather than the typical stalking pattern of other large pantherines. In this study, we conducted dissections, detailed documentation, and illustrated the forelimb anatomy of two adult P. uncia specimens (1M/1F). Qualitative and quantitative data revealed an intriguing combination of functional adaptations illustrating a balance between the diverse demands of head-first descent, pouncing, climbing across rocky terrain, restraint of large prey, rapid pursuit, and navigating deep snow. In many forelimb proportions, P. uncia is intermediate between the cursorial Acinonyx jubatus (cheetah) and the scansorial forest dwelling Panthera onca (jaguar). Enlarged scapular and pectoral musculature provide stability to the shoulder girdle during grappling with large prey, as well as support during jumping and climbing. A small, unarticulated bony clavicle may provide greater stability to the forelimb, while still allowing flexibility. In the brachium and antebrachium of P. uncia, there is a functional compromise between the powerful grip needed for grasping large prey and the stability necessary for rapid pursuit of prey over uneven, rocky terrain. A unique bifurcation in the tendon of m. biceps brachii may provide additional functional stability at the radiohumeral joint. Intrinsic muscles of the palmar manus are broad and fleshy, acting as an enlarged surface area to evenly distribute body weight while walking on soft snow. However, muscles that act to provide fine manual manipulation are reduced, as in other large prey specialists. Overall, P. uncia displays morphological adaptive parallels with scansorial, large prey specializing pantherines, such as P. onca, while also showing adaptations for running.

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.

Diffusible iodine-based contrast-enhanced computed tomography (diceCT): an emerging tool for rapid, high-resolution, 3-D imaging of metazoan soft tissues.

Morphologists have historically had to rely on destructive procedures to visualize the three-dimensional (3-D) anatomy of animals. More recently, however, non-destructive techniques have come to the forefront. These include X-ray computed tomography (CT), which has been used most commonly to examine the mineralized, hard-tissue anatomy of living and fossil metazoans. One relatively new and potentially transformative aspect of current CT-based research is the use of chemical agents to render visible, and differentiate between, soft-tissue structures in X-ray images. Specifically, iodine has emerged as one of the most widely used of these contrast agents among animal morphologists due to its ease of handling, cost effectiveness, and differential affinities for major types of soft tissues. The rapid adoption of iodine-based contrast agents has resulted in a proliferation of distinct specimen preparations and scanning parameter choices, as well as an increasing variety of imaging hardware and software preferences. Here we provide a critical review of the recent contributions to iodine-based, contrast-enhanced CT research to enable researchers just beginning to employ contrast enhancement to make sense of this complex new landscape of methodologies. We provide a detailed summary of recent case studies, assess factors that govern success at each step of the specimen storage, preparation, and imaging processes, and make recommendations for standardizing both techniques and reporting practices. Finally, we discuss potential cutting-edge applications of diffusible iodine-based contrast-enhanced computed tomography (diceCT) and the issues that must still be overcome to facilitate the broader adoption of diceCT going forward.

Bandaging, endoscopy, and surgery in the emergency avian patient.

This article is divided into three parts and describes procedures used in avian medicine after initial stabilization. The first part includes the application of bandages and splints for fractures. The second part describes the use of endoscopy to examine the choana, oral cavity, trachea, and, to a lesser extent, internal organs. The last part discusses equipment required and techniques used for esophagostomy tube placement, air sac cannulation, and surgery, with approaches to the coelomic cavity and a select number of surgical procedures. This article is intended to provide the emergency animal clinician with knowledge necessary to provide basic stabilization for avian patients and knowledge of procedures that can be performed by the experienced clinician.