Computed tomographic and gross anatomy of the head of the blue-fronted Amazon parrot (Amazona aestiva).

The blue-fronted Amazon parrot is an extremely popular pet bird in Brazil. These birds are commonly raised in captivity and are often seen in veterinary practice. Modern imaging modalities such as computed tomography (CT), which had not been widely used in wild and exotic bird medicine until recently, are now becoming more popular due to wider availability and higher diagnostic accuracy. However, proper interpretation of tomographic findings requires species-specific anatomical references. Studies investigating normal tomographic anatomy of parrots are scarce. This study set out to describe the normal anatomy of the head of the blue-fronted amazon parrot (Amazona aestiva) using conventional CT. Anatomical descriptions may contribute to future comparative morphology studies and assist in clinical practice. The head of the blue-fronted Amazon parrot is structurally similar to other bird species. Major differences detected were are as follows: size and position of nasal conchae (long middle concha and small caudal concha located at the end of the nasal cavity), infraorbital sinus aperture located on the lateral aspect of the nasal cavity, presence of a nasopharyngeal duct connecting the nasal and oral cavities, longer infraorbital sinus with a larger number of caudal compartments and paraglossum with morphological features unique to psittacines. High-quality CT images were vital for identification and detailed description of most head structures. Multiplanar reconstruction was a useful tool for complete visualization of the head. However, conventional CT images were not good enough for visualization of the inner ear and related structures, as well the paratympanic sinus.

Radiographic Measurements of the Cardiac Silhouette in Healthy Blue-Fronted Amazon Parrots (Amazona aestiva).

The objective of this investigation was to determine radiographic measurements, without chemical restraint, of the cardiac silhouette in 34 healthy, adult blue-fronted Amazon parrots (Amazona aestiva) of unknown sex with a mean body weight of 393 g. The birds were fasted 3 hours before the radiographic examinations. Three thoracic radiographic views (ventrodorsal, right lateral, and left lateral) were obtained from each bird for assessment. There was no significant statistical difference between right and left radiographic measurements. The mean values of the measurements in the ventrodorsal views were heart width of 21.04 mm and coelomic cavity width of 50.61 mm. The mean values of the measurements in the lateral views were left heart length of 23.44 mm, right heart length of 23.40 mm, left sternal length of 65.69 mm, and right sternal length of 65.03 mm. A strong correlation and ratio of 43% between the heart width and coelomic cavity width and a moderate correlation and ratio of 36% between the heart length and sternal length were observed. In conclusion, the radiographic measurements of the cardiac silhouette in healthy blue-fronted Amazon parrots can be obtained without chemical restraint. The values obtained can be used to assist in the detection of cardiomegaly or microcardia in blue-fronted Amazon parrots.

Applicability of optical coherence tomography in blue-fronted parrots (Amazona aestiva).

OBJECTIVE: Optical coherence tomography (OCT) measurement of adult blue-fronted parrots (Amazona aestiva), free from infectious, inflammatory or neoplastic systemic diseases and from any ophthalmological illness, aim at its characterization, as well as to standardize the examination technique for the species. PROCEDURE: Pupillary dilation was achieved with rocuronium bromide (5 mg/mL) at 0, 2, 15, 17, 30, and 32 minutes. The animals were sedated with midazolam maleate (0.5 mg/kg/IM) and anesthetized with propofol (5.0 mg/kg/IV). Measurements were made to evaluate the thickness of the total retina (TR), sensorineural retinal (SR), and ganglion cell complex (GCC), 2 millimeters (mm) from the pecten toward the fovea. OCT data were compared to measurements of retinal histological slides from enucleated eyes of blue-fronted parrots, scanned in automatic fluorescence microscope and measured with by the VS-ASW® software. RESULTS: Averages of measurements from the 43 retinas evaluated by OCT were TR: 279.40 micrometers (µm), SR: 255.90 µm, and GCC: 138.60 µm, respectively, and the measurements of six retinas using fluorescence microscopy were 260.30 µm for TR, 238.20 µm for SR, and 129.30 µm for GCC, demonstrating a high correlation coefficient between all measurements (r = .8698, P < .0001). It is also possible to evaluate the anatomy of the retina and to identify its layers, variations and abnormalities using OCT images. Variations were found between the different areas of the retina, both in the images of the histological slides and in the images of the OCT. CONCLUSION: Optical coherence tomography is a valuable technique for in vivo evaluation of retinal structures in blue-front parrots, providing detailed and accurate images. This method improves the understanding of retinal diseases, monitoring the beginning, progression and therapy of retinal diseases, in the same individuals during longitudinal studies. In comparison to histological investigations, OCT enables imaging in vivo, therefore reducing the number of euthanized animals or enucleated eyes.

Computed tomographic and radiographic morphometric study of cardiac and coelomic dimensions in captive blue-fronted Amazon parrots (Amazona aestiva, Linnaeus, 1758) with varying body condition scores.

This study aimed to assess radiographic and tomographic cardiac parameters, including width and length of the heart, and the ratio of heart width to coelom width of blue-fronted Amazon parrots (Amazona aestiva) with varying body condition scores. Thirty-five captive birds were included in the study and were allocated into one of three groups according to their respective body condition score: lean, ideal and obese. No differences were observed among the groups with regard to radiographic and tomographic measurements. Computed tomography enabled better identification of the structures of the cardiovascular system without interference from the overlying structures of the celomatic cavity observed in radiographic images. However, radiographic examinations should still be considered the standard screening method to identify cardiac alterations, such as increased or reduced organ dimensions. Standardizing the techniques and measurements performed in this study may serve as a basis for further research in the field.

Morphologic and quantitative evaluation of bone marrow aspirates from Hispaniolan Amazon parrots (Amazona ventralis).

BACKGROUND: Bone marrow aspirate assessments provide valuable information about hematopoietic status and hematologic disease. Hematopoietic cell differentials and morphologies have been anecdotally described in psittacines, but quantitative studies are lacking. OBJECTIVES: We aimed to determine differential cell counts and calculate granulocyte:erythroid (G:E) ratios in bone marrow aspirates from Hispaniolan Amazon parrots and report representative morphologies of the hematopoietic cells. METHODS: Bone marrow aspirates were collected from 32 clinically healthy, captive, parrots. Peripheral blood was obtained for CBCs. Bone marrow differential cell counts (%) were determined by counting 500 cells on modified Wright's-stained smears. G:E ratios were calculated. Representative images of hematopoietic cells at all stages of development were taken. RESULTS: Of the 32 parrots sampled, 17 bone marrow samples were of sufficient cellularity and quality for evaluation. Erythroid cells comprised 68.9 ± 8.6% (total ± SD) of the hematopoietic cells and consisted primarily of early- and late-stage polychromatophilic rubricytes (43.6 ± 2.1% of total erythroid cells). Granulocytic cells comprised 28.1 ± 3.8% of the hematopoietic cells and consisted primarily of mature and band heterophils (11.9 ± 5.2% and 6.5 ± 3.4%, respectively, of total granulocytic cells). A unique morphologic finding in avian progranulocytes was the presence of multiple different granules. The G:E ratio was 0.4 ± 0.2 (median 0.4, range 0.1-0.9). Thrombocyte lineage cells could not be reliably identified and were not counted. CBC results were largely within expected limits. CONCLUSIONS: The low G:E ratios observed could be normal in this species; however, these ratios could be affected by factors related to sampling and cell identification. These findings will be a valuable resource for the diagnostic evaluation of clinical bone marrow samples from Hispaniolan Amazon parrots and could serve as a general reference for psittacine bone marrow evaluation.

Descrição anatômica de esqueletos de papagaios do gênero Amazona através da utilização de radiografias / Anatomical description of Amazona gender parrot's skeletons through the use of radiography

O esqueleto de papagaios da espécie Amazona aestiva foi descrito e comparado com representantes de outras espécies do gênero Amazona. Para tanto, foram utilizados 22 exemplares da espécie Amazona aestiva; dois das espécies Amazona vinacea; Amazona rhodocorythae, Amazona farinosa, além de um exemplar das espécies Amazona brasiliensis e Amazona pretrei, doados após morte natural pelo Criadouro Poços de Caldas. Foram realizadas radiografias de corpo inteiro, variando de decúbito lateral direito ou esquerdo, no caso das projeções latero-laterais, e em decúbito dorsal, no caso da projeção ventro-dorsal. Independentemente da espécie, os crânios dos papagaios estudados puderam ser classificados como pró-cinéticos, por apresentarem liberdade de movimentos em sua porção rostral. Na maioria dos casos, a coluna vertebral esteve formada por 12 vértebras cervicais, seis vértebras torácicas livres, sinsacro (formado pela fusão da última vértebra torácica, 7 lombosacrais e uma caudal), cinco vértebras caudais livres e pelo pigóstilo (formado por três vértebras caudais fusionadas) e, apesar de diferenças pontuais, o esqueleto apendicular torácico e pélvico se mostrou muito semelhante ao observado para outros gêneros de aves e, inclusive, não foi possível observar dimorfismo sexual através das características anatômicas dos esqueletos dos papagaios trabalhados.

This study describes the skeleton of Amazona aestiva parrots and compared it with representatives of other Amazona species. To this end, we used 22 specimens of Amazona aestiva, two specimens each of Amazona vinacea; Amazona rhodocorythae, Amazona farinosa and one specimen each of Amazona brasiliensis and Amazona pretrei donated after natural death by Poços de Caldas Breeding Park. Full body radiographs were taken, in either the right or left lateral decubitus position, in the case of laterolateral projections, and in supine position, in the case of ventrodorsal projection. Regardless of the species, skulls of the parrots were classified as prokinetic, because of free movements in their rostral portion. In most cases, the spine consisted of: 12 cervical vertebrae, six free thoracic vertebrae, synsacrum (formed by the fusion of the last thoracic vertebrae, 7 lumbosacral vertebrae and one caudal vertebrae), five free caudal vertebrae and the pygostyle (formed by three fused caudal vertebrae). Despite punctual differences, thoracic and pelvic appendicular skeleton proved to be very similar to that observed for other genera of birds. In addition, there was no sexual dimorphism considering the anatomical characteristics of the skeletons of parrots analyzed.

Spectral tuning of Amazon parrot feather coloration by psittacofulvin pigments and spongy structures.

The feathers of Amazon parrots are brightly coloured. They contain a unique class of pigments, the psittacofulvins, deposited in both barbs and barbules, causing yellow or red coloured feathers. In specific feather areas, spongy nanostructured barb cells exist, reflecting either in the blue or blue-green wavelength range. The blue-green spongy structures are partly enveloped by a blue-absorbing, yellow-colouring pigment acting as a spectral filter, thus yielding a green coloured barb. Applying reflection and transmission spectroscopy, we characterized the Amazons' pigments and spongy structures, and investigated how they contribute to the feather coloration. The reflectance spectra of Amazon feathers are presumably tuned to the sensitivity spectra of the visual photoreceptors.

Estimation of intrathoracic arterial diameter by means of computed tomographic angiography in Hispaniolan Amazon parrots.

OBJECTIVE: To establish a computed tomography (CT)-angiography protocol and measure the diameters of major arteries in parrots. ANIMALS: 13 Hispaniolan Amazon parrots (Amazona ventralis). PROCEDURES: 16-slice CT scanning was used to measure the apparent diameter of the ascending aorta, abdominal aorta, pulmonary arteries, and brachiocephalic trunk. Before scanning, all birds underwent ECG and echocardiographic assessment and were considered free of detectable cardiovascular diseases. Each bird was anesthetized, and a precontrast helical CT scan was performed. Peak aortic enhancement was established with a test bolus technique via dynamic axial CT scan over a predetermined single slice. An additional bolus of contrast medium was then injected, and a helical CT-angiography scan was performed immediately afterward. Arterial diameter measurements were obtained by 2 observers via various windows before and after injection, and intra- and interobserver agreement was assessed. RESULTS: Reference limits were determined for arterial diameter measurements before and after contrast medium administration in pulmonary, mediastinal, and manual angiography windows. Ratios of vertebral body diameter to keel length were also calculated. Intraobserver agreement was high (concordance correlation coefficients ≥ 0.95); interobserver agreement was medium to high (intraclass correlation coefficients ≥ 0.65). CONCLUSIONS AND CLINICAL RELEVANCE: CT-angiography was safe and is of potential diagnostic value in parrots. We recommend performing the angiography immediately after IV injection of 3 mL of iohexol/kg. Arterial diameter measurements at the described locations were reliable.

B-mode ultrasonography biometry of the Amazon Parrot (Amazona aestiva) eye.

PURPOSE: Ultrasonographic evaluation of the eye is a relatively recent addition to routine ophthalmic diagnostics in small animal ophthalmology. Some parameters for ophthalmic biometry have been established. There are few studies in clinical avian ophthalmology that describe ultrasound images of eye in some nocturnal avian species and in other birds that do not belong to the Brazilian fauna, but the psittacine family is not represented. The purpose of this study was to describe the following measurements: the distances between cornea and anterior lens capsule (D1) between the anterior and posterior lens capsule (D2), between posterior lens capsule and optic papilla (D3) and the axial length. METHOD: Sixty four transpalpebral ocular ultrasound examinations were performed on 32 Blue fronted Amazon parrots (Amazona aestiva) with no history of previous ophthalmic disease. RESULT AND DISCUSSION: The measurements were taken in sagital planes using a 10 MHz linear probe without a standoff pad. The mean values for the left eye were; D1 0.17 ± 0.03 cm, D2 0.35 ± 0.02 cm, D3 0.73 ± 0.04 cm and the axial length 1.26 ± 0.06 cm. In the right eye D1 0.17 ± 0.02 cm, D2 0.34 ± 0.02 cm, D3 0.74 ± 0.03 cm and the axial length 1.25 ± 0.05 cm. No significant statistical difference was observed among the birds or between the left and right eye. The description of these parameters will allow the veterinary practitioner to evaluate the structural changes that specific diseases may cause in these animals.

Radiographic evaluation of perching-joint angles in cockatiels (Nymphicus hollandicus), Hispaniolan Amazon parrots (Amazona ventralis), and barred owls (Strix varia).

Information on perching-joint angles in birds is limited. Joint immobilization in a physiologic perching angle has the potential to result more often in complete restoration of limb function. We evaluated perching-joint angles in 10 healthy cockatiels (Nymphicus hollandicus), 10 Hispaniolan Amazons (Amazona ventralis), and 9 barred owls (Strix varia) and determined intra- and interobserver variability for goniometric measurements in 2 different radiographic projections. Intra- and interobserver variation was less than 7% for all stifle and intertarsal joint measurements but frequently exceeded 10% for the hip-joint measurements. Hip, stifle, and intertarsal perching angles differed significantly among cockatiels, Hispaniolan Amazon parrots, and barred owls. The accuracy of measurements performed on straight lateral radiographic projections with superimposed limbs was not consistently superior to measurements on oblique projections with a slightly rotated pelvis. Stifle and intertarsal joint angles can be measured on radiographs by different observers with acceptable variability, but intra- and interobserver variability for hip-joint-angle measurements is higher.

Protein requirements for Blue-fronted Amazon (Amazona aestiva) growth.

The objective of this study was to evaluate the protein requirements for hand-rearing Blue-fronted Amazon parrots (Amazona aestiva). Forty hatchlings were fed semi-purified diets containing one of four (as-fed basis) protein levels: 13%, 18%, 23% and 28%. The experiment was carried out in a randomized block design with the initial weight of the nestling as the blocking factor and 10 parrots per protein level. Regression analysis was used to determine relationships between protein level and biometric measurements. The data indicated that 13% crude protein supported nestling growth with 18% being the minimum tested level required for maximum development. The optimal protein concentration for maximum weight gain was 24.4% (p = 0.08; r(2) = 0.25), tail length 23.7% (p = 0.09; r(2) = 0.19), wing length 23.0% (p = 0.07; r(2) = 0.17), tarsus length 21.3% (p = 0.06; r(2) = 0.10) and tarsus width 21.4% (p = 0.07; r(2) = 0.09). Tarsus measurements were larger in males (p < 0.05), indicating that sex must be considered when studying developing psittacines. These results were obtained using a highly digestible protein and a diet with moderate metabolizable energy levels.