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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
in Journal of the American Veterinary Medical Association
in Journal of the American Veterinary Medical Association

Abstract

Objective

To evaluate the oncotic, hemodilutional, and hemostatic effects of IV infusions of a large volume of isotonic saline solution and 2 doses of 6% hydroxyethyl starch (HES) in clinically normal ponies.

Animals

12 adult ponies.

Procedure

Ponies were assigned to 3 treatment groups and received the following IV infusions: 80 ml of 0.9% sodium chloride/kg; 10 ml of 6% HES (in 0.9% sodium chloride)/kg; or 20 ml of 6% HES (in 0.9% sodium chloride)/kg. Blood samples were collected for determination of colloid oncotic pressure (COP), PCV, plasma total protein concentration, platelet count, von Willebrand factor antigen (vWf:Ag) activity, fibrinogen concentration, prothrombin time, activated partial thromboplastin time (APTT), and factor VIII coagulant (FVIII:C) activity. A rocket immunoelectrophoretic procedure was used for determination of vWf:Ag activity. A modification of the APTT assay was used for determination of FVIII:C activity. Cutaneous bleeding time was determined, using a template method.

Results

Mean COP was persistently increased over baseline values in the face of hemodilution in HES-treated ponies. Prothrombin time, APTT, and fibrinogen concentrations decreased after infusions and vWf:Ag and FVIII:C activities were decreased in dosedependent manner in HES-treated ponies. Though cutaneous bleeding time was not significantly affected in ponies of any group, a trend toward prolongation of bleeding time was evident in ponies receiving 20 ml of HES/kg. This trend appeared to be associated with marked decrement in vWf:Ag activity at this dosage.

Conclusions and Clinical Relevance

Infusion of HES in clinically normal ponies increases COP, and exerts dose-dependent hemodilutional effects and dose-dependent effects on specific hemostatic variables. Thus, HES may be useful for resuscitative fluid treatment of horses. (Am J Vet Res 1997;58:541–548)

Free access
in American Journal of Veterinary Research

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
in Journal of the American Veterinary Medical Association

Abstract

Objective—To measure epithelial cell percentages and somatic cell counts (SCCs) in milk and determine whether isoflupredone acetate reduces mammary gland epithelial cell sloughing in cows with acute endotoxin-induced mastitis.

Animals—13 lactating Holstein cows.

Procedures—Determination of SCC and flow cytometric analysis of cytokeratin-positive (epithelial) cells in milk were performed before and 12 hours after induction of mastitis via intramammary administration of bacterial endotoxin in 8 cows and at the same time points in 5 cows without mastitis. Endotoxin-treated cows received isoflupredone acetate (20 mg) or saline (0.9% NaCl) solution (n = 4/group) IV after signs of mastitis developed.

Results—At the 12-hour time point, mean ± SD percentage of epithelial cells in milk increased from 2.74 ± 1.93% to 42.11 ± 36.21% and decreased from 5.73 ± 4.52% to 5.31 ± 1.93% in milk from cows with and without mastitis, respectively. Median (range) SCC in milk increased from 195,000 cells/mL (17,000 to 442,000 cells/mL) to 5,437,500 cells/mL (69,000 to 11,036,000 cells/mL) and from 19,000 cells/mL (9,000 to 125,000 cells/mL) to 51,000 cells/mL (10,000 to 835,000 cells/mL) in cows with and without mastitis, respectively. Changes in these variables were significantly greater in mastitis-affected cows. Administration of isoflupredone acetate did not affect epithelial cell percentage or SCC in milk.

Conclusions and Clinical Relevance—During the early phase of endotoxin-induced mastitis in dairy cows, large numbers of epithelial cells were sloughed into the milk. Epithelial cell damage likely precedes an influx of immune cells into affected mammary glands and may contribute to breakdown of the blood-milk barrier.

Full access
in American Journal of Veterinary Research
in Journal of the American Veterinary Medical Association

Summary

Medical records were reviewed for 93 dogs with bacterial pneumonia from which transtracheal aspiration samples were obtained for culturing of Mycoplasma spp and aerobic bacteria. On the basis of culture results, there were 65 Mycoplasma-positive dogs, including 7 dogs for which only Mycoplasma spp were isolated, and 28 Mycoplasma-negative dogs. Most dogs were > 5 years old, and differences in breed or gender distribution among the 3 groups of dogs were not detected. Hematologic and serum biochemical analysis results did not differ significantly between Mycoplasma-positive and Mycoplasma-negative dogs. Fifty-three of 93 (57%) dogs had a concurrent medical problem that may have predisposed them to developing bacterial pneumonia as a sequelae to aspiration or immunosuppression. Mycoplasma-positive dogs were significantly (P < 0.005) more likely to have > 1 species of bacteria isolated from their transtracheal aspiration samples. Clinical outcome was favorable when antimicrobials were selected on the basis of antimicrobial susceptibility results for the other bacterial isolates and not on results of the antimicrobial activity against Mycoplasma spp. It could not be determined whether Mycoplasma spp were primary pathogens or only opportunists.

Free access
in Journal of the American Veterinary Medical Association

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