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  • Author or Editor: Mads F. Bertelsen x
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Abstract

Objective—To characterize the effects of propofol administered at 10 and 20 mg/kg (4.5 and 9 mg/lb) via the supravertebral venous sinus in red-eared sliders (Trachemys scripta).

Design—Prospective, masked randomized crossover study.

Animals—10 adult female red-eared sliders.

Procedures—Propofol was administered via the supravertebral sinus. Skeletal muscle tone of neck, forelimbs, hind limbs, and tail; heart rate; palpebral, corneal, and tap reflexes; response to deep pain; and spontaneous movement were recorded.

Results—Mean induction times were 1.7 ± 2.4 minutes and 0.9 ± 1.4 minutes at propofol doses of 10 and 20 mg/kg, respectively. Significant differences between the 2 doses were found in anesthetic duration, duration of the plateau phase, and time to recovery of skeletal muscle tone. A greater proportion of turtles in 20 mg/kg trials had loss of palpebral reflexes and sensation of deep pain, whereas corneal and spinal reflexes remained highly conserved at both doses. No significant differences were detected in time to maximal loss of skeletal muscle tone or in time to loss or recovery of reflexes. Total anesthetic times were 63.2 ± 23.8 minutes and 90.5 ± 32.3 minutes for 10 and 20 mg/kg trials, respectively. Heart rates remained constant between 30 and 40 beats/min with both doses.

Conclusions and Clinical Relevance—Propofol administration via the supravertebral sinus was a rapid and reliable means of achieving anesthesia in healthy red-eared sliders. Doses of 10 to 20 mg/kg should be adequate for short procedures or for induction prior to inhalation anesthesia.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To characterize physiologic responses of ball pythons (Python regius) following a minor surgical procedure and investigate the effects of 2 commonly used analgesics on this response.

Animals—15 healthy ball pythons.

Procedures—Snakes were randomly assigned to receive 1 of 3 treatments: meloxicam (0.3 mg/kg [0.14 mg/lb]; n = 5), butorphanol (5 mg/kg [2.3 mg/lb]; 5), or saline (0.9% NaCl) solution (5) before catheterization of the vertebral artery. Plasma concentrations of catecholamines and cortisol, blood pressure, heart rate, and blood gas values were measured at various times for 72.5 hours after catheterization. The 72.5-hour point was defined as baseline.

Results—Heart rate of ball pythons increased significantly during the first hour following surgery. Mean plasma epinephrine concentration increased slightly at 2.5 hours after surgery, whereas mean plasma cortisol concentration increased beginning at 1.5 hours, reaching a maximum at 6.5 hours. Mean blood pressure increased within the first hour but returned to the baseline value at 2.5 hours after surgery. After 24.5 hours, blood pressure, heart rate, and plasma hormone concentrations remained stable at baseline values. There were no significant differences in values for physiologic variables between snakes that received saline solution and those that received meloxicam or butorphanol.

Conclusions and Clinical Relevance—Measurement of physiologic variables provides a means of assessing postoperative pain in snakes. Meloxicam and butorphanol at the dosages used did not decrease the physiologic stress response and did not appear to provide analgesic effects in ball pythons.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine minimum alveolar concentration (MAC) of isoflurane in mechanically ventilated Dumeril monitors (Varanus dumerili).

Design—Prospective study.

Animals—10 healthy adult Dumeril monitors.

Procedure—Anesthesia was induced with isoflurane in oxygen delivered through a face mask. Monitors were endotracheally intubated, and end-tidal and inspired isoflurane concentrations were continuously measured. After equilibration at an end-tidal-toinspired isoflurane concentration ratio of > 0.9 for 20 minutes, an electrical stimulus (50 Hz, 50 V) was delivered to the ventral aspect of the tail for up to 1 minute and the monitor was observed for purposeful movement. End-tidal isoflurane concentration was then decreased by 10%, and equilibration and stimulation were repeated. The MAC was calculated as the mean of the lowest end-tidal isoflurane concentration that prevented positive response and the highest concentration that allowed response. A blood sample for blood gas analysis was collected from the tail vein at the beginning and end of the anesthetic period.

Results—Mean ± SD MAC of isoflurane was 1.54 ± 0.17%. Mean heart rates at the upper and lower MAC values were 32.4 ± 3 beats/min and 34 ± 4.5 beats/min, respectively. During the experiment, Paco2 decreased significantly from 43.1 mm Hg to 27.9 mm Hg and blood pH and HCO3 concentration increased significantly from 7.33 to 7.64 and from 25.3 to 32.9 mmol/L, respectively.

Conclusions and Clinical Relevance—The MAC of isoflurane in Dumeril monitors was similar to that reported in mammals but lower than values reported in other reptiles. This difference may be reflective of the more advanced cardiovascular physiologic features of monitor lizards. (J Am Vet Med Assoc 2005; 226:1098–1101)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine the minimum alveolar concentration (MAC) of sevoflurane and assess the sevoflurane-sparing effect of coadministration of nitrous oxide in mechanically ventilated Dumeril monitors (Varanus dumerili).

Design—Prospective crossover study.

Animals—10 healthy adult Dumeril monitors.

Procedure—Anesthesia was induced with sevoflurane in 100% oxygen or sevoflurane in 66% nitrous oxide (N2O) with 34% oxygen, delivered through a face mask. Monitors were endotracheally intubated, and end-tidal and inspired isoflurane concentrations were measured continuously; MAC was determined by use of a standard bracketing technique. An electrical stimulus (50 Hz, 50 V) was delivered to the ventral aspect of the tail as the supramaximal stimulus. A blood sample for blood gas analyses was collected from the ventral coccygeal vessels at the beginning and end of the anesthetic period. An interval of at least 7 days was allowed to elapse between treatments.

Results—The MAC ± SDs of sevoflurane in oxygen and with N2O were 2.51 ± 0.46% and 1.83 ± 0.33%, respectively. There was a significant difference between the 2 treatments, and the mean MAC-reducing effect of N2O was 26.4 ± 11.4%. Assuming simple linear additivity of sevoflurane and N2O, the MAC for N2O was estimated to be 244%. No significant differences in blood gas values—with the predictable exception of oxygen pressure—were detected between the 2 groups.

Conclusions and Clinical Relevance—The MAC of sevoflurane in Dumeril monitors is similar to that reported for other species. The addition of N2O significantly decreased the MAC of sevoflurane in this species. (J Am Vet Med Assoc 2005;227:575–578)

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in Journal of the American Veterinary Medical Association