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Abstract

Objective—To determine aqueous humor flow rate (AHFR) in an avian species by use of anterior segment fluorophotometry.

Animals—9 healthy red-tailed hawks (Buteo jamaicensis; 4 males and 5 females) that ranged from 8 months to 8 years of age.

Procedures—A protocol was developed for fluorophotometric determination of AHFR. Topical administration of 10% fluorescein was used to load the corneas, and corneal and aqueous humor fluorescein concentrations were measured approximately 5, 6.5, and 8 hours later. Concentration-versus-time plots were generated, and slopes and cornea-to-aqueous humor concentration ratios from these plots were used to manually calculate flow rates.

Results—Mean ± SD AHFRs for the right eye, left eye, and both eyes were 3.17 ± 1.36 μL/min (range, 1.67 to 6.21 μL/min), 2.86 ± 0.88 μL/min (range, 2.04 to 4.30 μL/min), and 2.90 ± 0.90 μL/min (range, 1.67 to 4.42 μL/min), respectively. The AHFRs were similar for right and left eyes. These flow rates represented a mean aqueous humor transfer coefficient of 0.0082/min, which is similar to that of mammalian species.

Conclusions and Clinical Relevance—The AHFR in red-tailed hawks was similar to that of most mammalian species, and the fractional egress was almost identical to that of other species. This information will allow a greater understanding of aqueous humor flow in avian eyes, which is crucial when evaluating diseases that affect avian eyes as well as medications that alter aqueous humor flow.

Full access
in American Journal of Veterinary Research
History

An immature northern goshawk (Accipiter gentilis) used for falconry was evaluated following suspected trauma that occurred during a hunting expedition 3 days earlier. On physical examination, the bird would not bear weight on its right leg, and the leg appeared to be dangling loosely. The talons on the right foot were unable to grasp, and there were no signs of deep pain sensation during physical examination. There was extensive bruising over the right hip joint. No other signs of neurologic deficits were detected. General anesthesia was induced with 4% inhalant isoflurane in oxygen and maintained at 2%

Restricted access
in Journal of the American Veterinary Medical Association
History

An adult captive male Harris hawk (Parabuteo unicinctus) with a puncture wound to the head was treated by a referring veterinarian. Doxycycline, meloxicam, and trimethoprim-sulfamethoxazole were prescribed. After 1 week of treatment by the owner at home, the wound resolved, but the hawk developed respiratory tract signs including coughing, wheezing, head shaking, and episodes of open-mouthed breathing. On physical examination at the University of Tennessee College of Veterinary Medicine, the hawk had yellow crusty material adhered to the opening of the glottis and respiratory wheezes were detected via auscultation. The hawk was treated with oxygen and placement

Restricted access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To standardize techniques for renal scintigraphy in birds, to use scintigraphy to assess gentamicin nephrotoxicosis in birds, to compare nuclear medicine assessments with histologic assessment of gentamicin nephrotoxicosis and serum uric acid concentrations, and to determine the radiopharmaceutical that best quantifies avian renal function.

Animals—12 domestic pigeons (Columba livia domestica).

Procedure—Serum uric acid concentrations were determined for all birds. Renal scintigraphy techniques that used technetium-m99 (99mTc)-dimercaptosuccinic acid (DMSA; 4 hours after injection) and 99mTc-diethylenetriamine pentaacetic acid (DTPA; 15- minute dynamic study) were evaluated in all birds. Renal biopsy specimens were collected following baseline scans. Number and size of renal tubule granules positive for periodic acid-Schiff stain were scored for severity (scale of 0 to 4). Nephrotoxicosis was induced by administration of gentamicin. Serum uric acid concentrations were measured, and 99mTc-DMSA and99mTc-DTPA scans were repeated after gentamicin administration. Birds were euthanatized, and complete necropsies were performed.

Results—Standard avian renal scintigraphy techniques were developed for 99mTc-DMSA and 99mTc- DTPA. Decreased renal radiopharmaceutical uptake for 99mTc-DMSA and 99mTc-DTPA indicated nephrotoxicosis. Cloacal accumulation of 99mTc-DTPA was significantly decreased after administration of gentamicin. Histologic grading of renal tissue before and after gentamicin administration confirmed nephrotoxicosis. Inconsistent serum uric acid concentrations could not be used to assess nephrotoxicosis.

Conclusions and Clinical Relevance—Renal nuclear scintigraphy is a useful, noninvasive means to determine renal function in birds. Although 99mTc-DMSA may prove useful in the evaluation of renal morphology, 99mTc-DTPA is the radiopharmaceutical agent of choice for the assessment of renal function in avian species. (Am J Vet Res 2003;64:453–462)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine 2-deoxy-2-fluoro (fluorine 18)-d-glucose (18FDG) biodistribution in the coelom of bald eagles (Haliaeetus leucocephalus).

Animals—8 healthy adult bald eagles.

Procedures—For each eagle, whole-body transmission noncontrast CT, 60-minute dynamic positron emission tomography (PET) of the celomic cavity (immediately after 18FDG injection), whole-body static PET 60 minutes after 18FDG injection, and whole-body contrast CT with iohexol were performed. After reconstruction, images were analyzed. Regions of interest were drawn over the ventricular myocardium, liver, spleen, proventriculus, cloaca, kidneys, and lungs on dynamic and static PET images. Standardized uptake values were calculated.

Results—Kidneys had the most intense 18FDG uptake, followed by cloaca and intestinal tract; liver activity was mild and slightly more intense than that of the spleen; proventricular activity was always present, whereas little to no activity was identified in the wall of the ventriculus. Activity in the myocardium was present in all birds but varied in intensity among birds. The lungs had no visibly discernible activity. Mean ± SD standardized uptake values calculated with representative regions of interest at 60 minutes were as follows: myocardium, 1. 6 ± 0.2 (transverse plane) and 1.3 ± 0.3 (sagittal plane); liver, 1.1 ± 0.1; spleen, 0.9 ± 0.1; proventriculus, 1.0 ± 0.1; cloaca, 4.4 ± 2.7; right kidney, 17.3 ± 1.0; left kidney, 17.6 ± 0.3; and right and left lungs (each), 0.3 ± 0.02.

Conclusions and Clinical Relevance—The study established the biodistribution of 18FDG in adult eagles, providing a baseline for clinical investigation and future research.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To compare induction and recovery characteristics and cardiopulmonary effects of isoflurane and sevoflurane in bald eagles.

Animals—17 healthy adult bald eagles.

Procedures—Anesthesia was induced with isoflurane or sevoflurane delivered in oxygen via a facemask in a crossover design with 4 weeks between treatments. Eagles were intubated, allowed to breathe spontaneously, and instrumented for cardiopulmonary measurements. Time to induction, extubation, and recovery, as well as smoothness of recovery, were recorded.

Results—Administration of sevoflurane resulted in a significantly quicker recovery, compared with isoflurane. Temperature, heart rate, and respiratory rate significantly decreased over time, whereas systolic (SAP), diastolic (DAP), and mean arterial blood pressure (MAP) significantly increased over time with each treatment. Temperature, heart rate, SAP, DAP, and MAP were significantly higher with isoflurane. Blood pH significantly decreased, whereas PaCO2 significantly increased over time with each treatment. Bicarbonate and total carbon dioxide concentrations significantly increased over time with each treatment; however, there was a significant time-treatment interaction. The PaO2 and arterial oxygen saturation increased over time with isoflurane and decreased over time with sevoflurane with a significant time-treatment interaction. Six eagles developed cardiac arrhythmias with isoflurane, as did 4 with sevoflurane anesthesia.

Conclusions and Clinical Relevance—Isoflurane and sevoflurane administration resulted in smooth, rapid induction of and recovery from anesthesia similar to other species. Isoflurane administration resulted in tachycardia, hypertension, and more arrhythmias, compared with sevoflurane. Sevoflurane was associated with fewer adverse effects and may be particularly beneficial in compromised bald eagles.

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE To evaluate mechanical properties of pigeon (Columba livia) cadaver intact humeri versus ostectomized humeri stabilized with a locking or nonlocking plate.

SAMPLE 30 humeri from pigeon cadavers.

PROCEDURES Specimens were allocated into 3 groups and tested in bending and torsion. Results for intact pigeon humeri were compared with results for ostectomized humeri repaired with a titanium 1.6-mm screw locking plate or a stainless steel 1.5-mm dynamic compression plate; the ostectomized humeri mimicked a fracture in a thin cortical bone. Locking plates were secured with locking screws (2 bicortical and 4 monocortical), and nonlocking plates were secured with bicortical nonlocking screws. Constructs were cyclically tested nondestructively in 4-point bending and then tested to failure in bending. A second set of constructs were cyclically tested non-destructively and then to failure in torsion. Stiffness, strength, and strain energy of each construct were compared.

RESULTS Intact specimens were stiffer and stronger than the repair groups for all testing methods, except for nonlocking constructs, which were significantly stiffer than intact specimens under cyclic bending. Intact bones had significantly higher strain energies than locking plates in both bending and torsion. Locking and nonlocking plates were of equal strength and strain energy, but not stiffness, in bending and were of equal strength, stiffness, and strain energy in torsion.

CONCLUSIONS AND CLINICAL RELEVANCE Results for this study suggested that increased torsional strength may be needed before bone plate repair can be considered as the sole fixation method for avian species.

Full access
in American Journal of Veterinary Research