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Abstract

Objective—To evaluate bronchial morphology endoscopically in rabbits and develop a valid nomenclature for the endobronchial branching pattern.

Animals—10 mature New Zealand White rabbits.

Procedures—Flexible bronchoscopy was performed in rabbits anesthetized with isoflurane via nasal mask. Airways were systematically evaluated from the larynx to the terminal branches accessible with a 2.5-mm–outer diameter flexible endoscope. Airway branching patterns were identified and assessed for variation among subjects.

Results—Airways of all rabbits were readily examined with the 2.5-mm flexible endoscope. Laryngeal structure and function were normal in each rabbit, and airway branching patterns in all rabbits evaluated were identical. At the carina, branching into left and right principal bronchi was evident. The left principal bronchus divided immediately into the left cranial and left caudal lobar bronchi. The left cranial lobe bronchus further divided into dorsal and ventral segmental bronchi. The left caudal lobe bronchus gave rise to branches originating dorsally, ventrally, and medially before continuing caudally. The right principal bronchus divided into the right cranial, right middle, and accessory lobar bronchi and continued distally as the right caudal lobar bronchus. The right cranial lobe bronchus also divided into dorsal and ventral segmental bronchi, and the right caudal lobe bronchus had branches that originated dorsally, ventrally, and medially.

Conclusions and Clinical Relevance—Definition of a standard nomenclature for airway branching in rabbits will allow precise localization of disease in clinical cases and accurate collection of airway samples in clinical and scientific evaluations.

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in American Journal of Veterinary Research

Abstract

Objective—To determine the mineral composition of calculi, anatomic locations of the calculi, and findings of urinalysis and bacteriologic culture of urine and calculi in guinea pigs with urolithiasis.

Design—Cross-sectional study.

Animals—127 guinea pigs.

Procedures—Records of urinary calculi that had been submitted to the University of California Stone Laboratory from 1985 through 2003 were reviewed. In addition, submissions of urinary calculi for evaluation by the laboratory were prospectively solicited from 2004 through 2007. Prospectively obtained calculi were accompanied by a urine sample for urinalysis and bacteriologic culture and a completed questionnaire. All calculi were analyzed by use of polarized light microscopy and infrared spectroscopy. A subset of calculi was examined by means of x-ray diffractometry (XRD).

Results—83% (43/52) of calculi from the laboratory database and 93% (70/75) of calculi that were prospectively solicited were composed of 100% calcium carbonate. Analysis via XRD confirmed that 5 of 6 calculi from a subset that had the greatest gross morphologic variation were composed of 100% calcite. Although many guinea pigs had received anti-microbials before bacteriologic cultures of urine were performed, Corynebacterium renale was isolated from 5 urine samples.

Conclusions and Clinical Relevance—Contrary to findings of other studies, urinary calculi analyzed for the present study were most commonly composed of 100% calcium carbonate, and infrared spectroscopy or XRD was necessary to differentiate this mineral from others. Treatments, including diet and husbandry practices, should be developed to help prevent development of calcium carbonate calculi in guinea pigs.

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in Journal of the American Veterinary Medical Association

Abstract

OBJECTIVE To determine effects of increasing plasma fentanyl concentrations on the minimum alveolar concentration (MAC) of isoflurane in rabbits.

ANIMALS 6 adult female New Zealand White rabbits (Oryctolagus cuniculus).

PROCEDURES Rabbits were anesthetized with isoflurane in oxygen; ventilation was controlled and body temperature maintained between 38.5° and 39.5°C. Fentanyl was administered IV by use of a computer-controlled infusion system to achieve 6 target plasma concentrations. Isoflurane MAC was determined in duplicate by use of the bracketing technique with a supramaximal electrical stimulus. Blood samples were collected for measurement of plasma fentanyl concentration at each MAC determination. The MAC values were analyzed with a repeated-measures ANOVA followed by Holm-Sidak pairwise comparisons.

RESULTS Mean ± SD plasma fentanyl concentrations were 0 ± 0 ng/mL (baseline), 1.2 ± 0.1 ng/mL, 2.2 ± 0.3 ng/mL, 4.4 ± 0.4 ng/mL, 9.2 ± 0.4 ng/mL, 17.5 ± 2.6 ng/mL, and 36.8 ± 2.4 ng/mL. Corresponding mean values for isoflurane MAC were 1.92 ± 0.16%, 1.80 ± 0.16%, 1.60 ± 0.23%, 1.46 ± 0.22%, 1.12 ± 0.19%, 0.89 ± 0.14%, and 0.70 ± 0.15%, respectively. Isoflurane MAC for plasma fentanyl concentrations ≥ 2.2 ng/mL differed significantly from the baseline value. In 3 rabbits, excessive spontaneous movement prevented MAC determination at the highest plasma fentanyl concentration.

CONCLUSIONS AND CLINICAL RELEVANCE Fentanyl reduced isoflurane MAC by approximately 60% in New Zealand White rabbits. Further studies will be needed to investigate the cardiorespiratory effects of isoflurane and fentanyl combinations in rabbits; however, fentanyl may prove to be a useful adjunct to inhalation anesthesia in this species.

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in American Journal of Veterinary Research

Abstract

Objective—To determine the stability and distribution of voriconazole in 2 extemporaneously prepared (compounded) suspensions stored for 30 days at 2 temperatures.

Sample Population—Voriconazole suspensions (40 mg/mL) compounded from commercially available 200-mg tablets suspended in 1 of 2 vehicles. One vehicle contained a commercially available suspending agent and a sweetening syrup in a 1:1 mixture (SASS). The other vehicle contained the suspending agent with deionized water in a 3:1 mixture (SADI).

Procedures—Voriconazole suspensions (40 mg/mL in 40-mL volumes) were compounded on day 0 and stored at room temperature (approx 21°C) or refrigerated (approx 5°C). To evaluate distribution, room-temperature aliquots of voriconazole were measured immediately after preparation. Refrigerated aliquots were measured after 3 hours of refrigeration. To evaluate stability, aliquots from each suspension were measured at approximately 7-day intervals for up to 30 days. Voriconazole concentration, color, odor, opacity, and pH were measured, and aerobic and anaerobic bacterial cultures were performed at various points.

Results—Drug distribution was uniform (coefficient of variation, < 5%) in both suspensions. On day 0, 87.8% to 93.0% of voriconazole was recovered; percentage recovery increased to between 95.1% and 100.8% by day 7. On subsequent days, up to day 30, percentage recovery was stable (> 90%) for all suspensions. The pH of each suspension did not differ significantly throughout the 30-day period. Storage temperature did not affect drug concentrations at any time, nor was bacterial growth obtained.

Conclusions and Clinical Relevance—Extemporaneously prepared voriconazole in SASS and SADI resulted in suspensions that remained stable for at least 30 days. Refrigerated versus room-temperature storage of the suspensions had no effect on drug stability.

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in American Journal of Veterinary Research

Abstract

Objective—To determine the median effective dose (ED50; equivalent to the minimum alveolar concentration [MAC]) of isoflurane, sevoflurane, and desflurane for anesthesia in iguanas.

Animals—6 healthy adult green iguanas.

Procedure—In unmedicated iguanas, anesthesia was induced and maintained with each of the 3 volatile drugs administered on separate days according to a Latin square design. Iguanas were endotracheally intubated, mechanically ventilated, and instrumented for cardiovascular and respiratory measurements. During each period of anesthesia, MAC was determined in triplicate. The mean value of 2 consecutive expired anesthetic concentrations, 1 that just permitted and 1 that just prevented gross purposeful movement in response to supramaximal electrical stimulus, and that were not different by more than 15%, was deemed the MAC.

Results—Mean ± SD values for the third MAC determination for isoflurane, sevoflurane, and desflurane were 1.8 ± 0.3%, 3.1 ± 1.0%, and 8.9 ± 2.1% of atmospheric pressure, respectively. The MAC for all inhaled agents was, on average, 22% greater for the first measurement than for the third measurement.

Conclusions and Clinical Relevance—Over time, MACs decreased for all 3 agents. Final MAC measurements were similar to values reported for other species. The decrease in MACs over time may be at least partly explained by limitations of anesthetic uptake and distribution imposed by the reptilian cardiorespiratory system. Hence, for a constant end-tidal anesthetic concentration in an iguana, the plane of anesthesia may deepen over time, which could contribute to increased morbidity during prolonged procedures.

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in American Journal of Veterinary Research

Abstract

Objective—To determine the effects of body position on lung and air-sac volumes in anesthetized and spontaneously breathing red-tailed hawks (Buteo jamaicensis).

Animals—6 adult red-tailed hawks (sex unknown).

Procedures—A crossover study design was used for quantitative estimation of lung and air-sac volumes in anesthetized hawks in 3 body positions: dorsal, right lateral, and sternal recumbency. Lung volume, lung density, and air-sac volume were calculated from helical computed tomographic (CT) images by use of software designed for volumetric analysis of CT data. Effects of body position were compared by use of repeated-measures ANOVA and a paired Student t test.

Results—Results for all pairs of body positions were significantly different from each other. Mean ± SD lung density was lowest when hawks were in sternal recumbency (–677 ± 28 CT units), followed by right lateral (–647 ± 23 CT units) and dorsal (–630 ± 19 CT units) recumbency. Mean lung volume was largest in sternal recumbency (28.6 ± 1.5 mL), followed by right lateral (27.6 ± 1.7 mL) and dorsal (27.0 ± 1.5 mL) recumbency. Mean partial air-sac volume was largest in sternal recumbency (27.0 ± 19.3 mL), followed by right lateral (21.9 ± 16.1 mL) and dorsal (19.3 ± 16.9 mL) recumbency.

Conclusions and Clinical Relevance—In anesthetized red-tailed hawks, positioning in sternal recumbency resulted in the greatest lung and air-sac volumes and lowest lung density, compared with positioning in right lateral and dorsal recumbency. Additional studies are necessary to determine the physiologic effects of body position on the avian respiratory system.

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in American Journal of Veterinary Research

Abstract

Case Description—An 8-month-old spayed female domestic ferret (Mustela putorius furo) was referred for examination to determine the cause of lethargy and severe anemia.

Clinical Findings—Initial examination revealed that the ferret was lethargic but with appropriate mentation. The only other abnormal findings were severe pallor of the mucous membranes, nasal planum, and skin and a PCV of 8%. Pure red cell aplasia (PRCA) was diagnosed on the basis of cytologic evaluation of a bone marrow biopsy specimen.

Treatment and Outcome—Medical treatment included blood transfusions, IM administration of iron dextran, oral administration of antimicrobials and gastrointestinal tract protectants, and SC administration of erythropoietin. Once PRCA was diagnosed, the ferret was orally administered prednisone, cyclosporine, and azathioprine. Nine months after onset of treatment, the PRCA was in remission and the ferret was doing well. Immunosuppressive treatment was discontinued at 14 months after onset of treatment, and 36 months after initial examination, the ferret appeared to be healthy.

Clinical Relevance—It is important that PRCA be considered as a differential diagnosis for a ferret with severe anemia. Prolonged immunosuppressive treatment was successful in the ferret described here. (J Am Vet Med Assoc 2010;237:695-700)

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in Journal of the American Veterinary Medical Association

Abstract

OBJECTIVE To determine the pharmacokinetics and sedative effects of 2 doses of a concentrated buprenorphine formulation after SC administration to red-tailed hawks (Buteo jamaicensis).

ANIMALS 6 adult red-tailed hawks.

PROCEDURES Concentrated buprenorphine (0.3 mg/kg, SC) was administered to all birds. Blood samples were collected at 10 time points over 24 hours after drug administration to determine plasma buprenorphine concentrations. After a 4-week washout period, the same birds received the same formulation at a higher dose (1.8 mg/kg, SC), and blood samples were collected at 13 time points over 96 hours. Hawks were monitored for adverse effects and assigned agitation-sedation scores at each sample collection time. Plasma buprenorphine concentrations were quantified by liquid chromatography–tandem mass spectrometry.

RESULTS Mean time to maximum plasma buprenorphine concentration was 7.2 minutes and 26.1 minutes after administration of the 0.3-mg/kg and 1.8-mg/kg doses, respectively. Plasma buprenorphine concentrations were > 1 ng/mL for mean durations of 24 and 48 hours after low- and high-dose administration, respectively. Mean elimination half-life was 6.23 hours for the low dose and 7.84 hours for the high dose. Mean agitation-sedation scores were higher (indicating some degree of sedation) than the baseline values for 24 hours at both doses. No clinically important adverse effects were observed.

CONCLUSIONS AND CLINICAL RELEVANCE Concentrated buprenorphine was rapidly absorbed, and plasma drug concentrations considered to have analgesic effects in other raptor species were maintained for extended periods. Most birds had mild to moderate sedation. Additional studies are needed to evaluate the pharmacodynamics of these doses of concentrated buprenorphine in red-tailed hawks.

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in American Journal of Veterinary Research

Abstract

Objective—To determine the distribution and clinical outcome of ocular lesions in snakes.

Design—Retrospective case series.

Animals—67 snakes with ocular lesions.

Procedures—Signalment, lesion duration, diagnosis, treatment, and clinical outcome were recorded for all snakes with ocular lesions that were examined at a veterinary teaching hospital from 1985 to 2010.

Results—71 ocular lesions were detected in 67 of 508 (13%) snakes examined. Affected snakes were of the families Boidae, Pythonidae, Colubridae, and Viperidae. The distribution of ocular lesions did not vary by taxonomic family, age, or sex; however, snakes from the genus Epicrates with ocular lesions were overrepresented in the population. The most commonly diagnosed ocular lesions were retained spectacle (n = 41), pseudobuphthalmos or subspectacular abscess (13), trauma (8), and cataracts (4). Pseudobuphthalmos or subspectacular abscess developed more frequently in Colubridae than in non-Colubridae snakes. Of the 16 snakes with retained spectacles for which data were available, the lesion recurred once in 4 snakes and multiple times in 5 snakes.

Conclusions and Clinical Relevance—Results indicated that retained spectacle was the most common ocular lesion diagnosed in snakes. Compared with other snakes with ocular lesions, snakes of the genus Epicrates had a higher than expected frequency of ocular lesions in general and snakes of the family Colubridae had a higher than expected frequency of pseudobuphthalmos or subspectacular abscess.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine induction doses, anesthetic constant rate infusions (CRI), and cardiopulmonary effects of propofol in red-tailed hawks and great horned owls and propofol pharmacokinetics in the owls during CRI.

Animals—6 red-tailed hawks and 6 great horned owls.

Procedure—The CRI dose necessary for a loss of withdrawal reflex was determined via specific stimuli. Anesthesia was induced by IV administration of propofol (1 mg/kg/min) and maintained by CRI at the predetermined dose for 30 minutes. Heart and respiratory rates, arterial blood pressures, and blood gas tensions were obtained in awake birds and at various times after induction. End-tidal CO2 (ETCO2) concentration and esophageal temperature were obtained after induction. Propofol plasma concentrations were obtained after induction and after completion of the CRI in the owls. Recovery times were recorded.

Results—Mean ± SD doses for induction and CRI were 4.48 ± 1.09 mg/kg and 0.48 ± 0.06 mg/kg/min, respectively, for hawks and 3.36 ± 0.71 mg/kg and 0.56 ± 0.15 mg/kg/min, respectively, for owls. Significant increases in PaCO2, HCO3, and ETCO2 in hawks and owls and significant decreases in arterial pH in hawks were detected. A 2-compartment model best described the owl pharmacodynamic data. Recovery times after infusion were prolonged and varied widely. Central nervous system excitatory signs were observed during recovery.

Conclusions and Clinical Relevance—Effects on blood pressure were minimal, but effective ventilation was reduced, suggesting the need for careful monitoring during anesthesia. Prolonged recovery periods with moderate-to-severe excitatory CNS signs may occur in these species at these doses. (Am J Vet Res 2003;64:677–683)

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in American Journal of Veterinary Research