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  • Author or Editor: Eva Rioja x
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Objective—To assess the sedative and cardiopulmonary effects of medetomidine and xylazine and their reversal with atipamezole in calves.

Animals—25 calves.

Procedures—A 2-phase (7-day interval) study was performed. Sedative characteristics (phase I) and cardiopulmonary effects (phase II) of medetomidine hydrochloride and xylazine hydrochloride administration followed by atipamezole hydrochloride administration were evaluated. In both phases, calves were randomly allocated to receive 1 of 4 treatments IV: medetomidine (0.03 mg/kg) followed by atipamezole (0.1 mg/kg; n = 6), xylazine (0.3 mg/kg) followed by atipamezole (0.04 mg/kg; 7), medetomidine (0.03 mg/kg) followed by saline (0.9% NaCl; 6) solution (10 mL), and xylazine (0.3 mg/kg) followed by saline solution (10 mL; 6). Atipamezole or saline solution was administered 20 minutes after the first injection. Cardiopulmonary variables were recorded at intervals for 35 minutes after medetomidine or xylazine administration.

Results—At the doses evaluated, xylazine and medetomidine induced a similar degree of sedation in calves; however, the duration of medetomidine-associated sedation was longer. Compared with pretreatment values, heart rate, cardiac index, and PaO2 decreased, whereas central venous pressure, PaCO2 , and pulmonary artery pressures increased with medetomidine or xylazine. Systemic arterial blood pressures and vascular resistance increased with medetomidine and decreased with xylazine. Atipamezole reversed the sedative and most of the cardiopulmonary effects of both drugs.

Conclusions and Clinical Relevance—At these doses, xylazine and medetomidine induced similar degrees of sedation and cardiopulmonary depression in calves, although medetomidine administration resulted in increases in systemic arterial blood pressures. Atipamezole effectively reversed medetomidine- and xylazine-associated sedative and cardiopulmonary effects in calves.

Full access
in American Journal of Veterinary Research


Case Description—A 4.6-month-old pot-bellied pig was evaluated because of non–weight-bearing lameness (grade 5/5) in the right forelimb of 4 days' duration.

Clinical Findings—Clinical and radiographic examination revealed a closed, lateral luxation of the right shoulder joint.

Treatment and Outcome—Initial attempts at closed reduction failed to provide adequate stability of the shoulder joint. Open reduction and internal fixation by placement of 2 lateral tension sutures with a system designed for canine cranial cruciate ligament repair provided adequate joint stability and a successful outcome.

Conclusions and Clinical Relevance—Stabilization of the shoulder joint with lateral tension sutures after open reduction should be considered for management of lateral shoulder luxation in pot-bellied pigs.

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in Journal of the American Veterinary Medical Association


Objective—To evaluate the clinical effects and pharmacokinetics of vancomycin in plasma and synovial fluid after intraosseous regional limb perfusion (IORLP) in horses and to compare results with those obtained after IV regional limb perfusion (IVRLP).

Animals—6 horses.

Procedures—1 forelimb of each horse received vancomycin hydrochloride (300 mg in 60 mL of saline [0.9% NaCl] solution) via IORLP; the contralateral limb received 60 mL of saline solution (control). Solutions were injected into the medullary cavity of the distal portion of the third metacarpal bone. Synovial fluid from the metacarpophalangeal (MTCP) and distal interphalangeal (DIP) joints and blood were collected prior to perfusion and 15, 30, 45, 65, and 90 minutes after beginning IORLP, and synovial fluid from the MTCP joint only and blood were collected 4, 8, 12, and 24 hours after beginning IORLP. Plasma urea and creatinine concentrations and clinical appearance of the MTCP joint region and infusion sites were determined daily for 7 days. Results were compared with those of a separate IVRLP study.

Results—Clinical complications were not observed after IORLP. Mean vancomycin concentration in the MTCP joint was 4 μg/mL for 24 hours after IORLP. Compared with IORLP, higher vancomycin concentrations were detected in the DIP joint after IVRLP. Compared with IVRLP, higher vancomycin concentrations were detected in the MTCP joint for a longer duration after IORLP.

Conclusions and Clinical Relevance—IORLP with 300 mg of vancomycin in a 0.5% solution was safe and may be clinically useful in horses. Intravenous and intraosseous routes may be better indicated for infectious processes in the DIP and MTCP joints, respectively.

Full access
in American Journal of Veterinary Research


Objective—To assess the effects of alterations in PaCO 2 and PaO 2 on blood oxygenation level–dependent (BOLD) signal intensity determined by use of susceptibility-weighted magnetic resonance imaging in brains of isoflurane-anesthetized dogs.

Animals—6 healthy dogs.

Procedures—In each dog, anesthesia was induced with propofol (6 to 8 mg/kg, IV) and maintained with isoflurane (1.7%) and atracurium (0.2 mg/kg, IV, q 30 min). During 1 magnetic resonance imaging session in each dog, targeted values of PaCO 2 (20, 40, or 80 mm Hg) and PaO 2 (100 or 500 mm Hg) were combined to establish 6 experimental conditions, including a control condition (PaCO 2, 40 mm Hg; PaO 2, 100 mm Hg). Dogs were randomly assigned to different sequences of conditions. Each condition was established for a period of ≥ 5 minutes before susceptibility-weighted imaging was performed. Signal intensity was measured in 6 regions of interest in the brain, and data were analyzed by use of an ANCOVA and post hoc Tukey-Kramer adjustments.

Results—Compared with control condition findings, BOLD signal intensity did not differ significantly in any region of interest. However, signal intensities in the thalamus and diencephalic gray matter decreased significantly during both hypocapnic conditions, compared with all other conditions except for the control condition.

Conclusions and Clinical Relevance—In isoflurane-anesthetized dogs, certain regions of gray matter appeared to have greater cerebrovascular responses to changes in PaCO 2 and PaO 2 than did others. Both PaO 2 and PaCO 2 should be controlled during magnetic resonance imaging procedures that involve BOLD signaling and taken into account when interpreting findings.

Full access
in American Journal of Veterinary Research


Objective—To evaluate the effects of various combinations of Paco2 and Pao2 values on brain morphometrics.

Animals—6 healthy adult dogs.

Procedures—A modified Latin square design for randomization was used. Dogs were anesthetized with propofol (6 to 8 mg/kg, IV), and anesthesia was maintained with isoflurane (1.7%) and atracurium (0.2 mg/kg, IV, q 30 min). Three targeted values of Paco2 (20, 40, and 80 mm Hg) and 2 values of Pao2 (100 and 500 mm Hg) were achieved in each dog, yielding 6 combinations during a single magnetic resonance (MR) imaging session. When the endpoints were reached, dogs were given at least 5 minutes for physiologic variables to stabilize before T1-weighted MR images were obtained. Total brain volume (TBV) and lateral ventricular volume (LVV) were calculated from manually drawn contours of areas of interest by use of a software program, with each dog serving as its own control animal. Three blinded investigators subjectively evaluated the lateral ventricular size (LVS) and the cerebral sulci width (CSW). Brain morphometric values were compared among the target blood gas states.

Results—No significant differences in TBV were found among target states. The LVV was significantly greater during hypocapnia, compared with hypercapnia at the same Pao2 value. With regard to the subjective evaluations, there were no significant differences among evaluators or among combinations of Pao2 and Paco2 values.

Conclusions and Clinical Relevance—The changes observed in LVV during hypocapnia and hypercapnia may serve as a potential confounding factor when neuromorphometric evaluations are performed in anesthetized dogs. (Am J Vet Res 2010;71:1011–1018)

Full access
in American Journal of Veterinary Research