OBJECTIVE To compare characteristics of recovery from isoflurane anesthesia in healthy nonpremedicated dogs after anesthetic induction by IV administration of tiletamine-zolazepam with those observed after induction by IV administration of alfaxalone, ketamine-diazepam, or propofol.
DESIGN Prospective, randomized crossover study.
ANIMALS 6 healthy adult hounds.
PROCEDURES Each dog underwent the 4 treatments in random order with a ≥ 7-day washout period between anesthetic episodes. Anesthesia was induced by IV administration of the assigned induction drug or combination (each to effect in 25% increments of calculated dose) and maintained with isoflurane in oxygen for 60 minutes. Cardiorespiratory variables and end-tidal isoflurane concentration (ETISO) were measured just before isoflurane administration was discontinued. Dogs were observed and video recorded during recovery. Recovery characteristics were retrospectively scored from recordings by 3 raters. Interrater and intrarater reliability of scoring was assessed by intraclass correlation coefficient calculation. Linear and mixed ANOVAs were used to compare extubation times, recovery scores, and body temperature among treatments.
RESULTS Most cardiorespiratory variables, body temperature, ETISO, and time to extubation did not differ between tiletamine-zolazepam and other induction treatments. Recovery scores were lower (indicating better recovery characteristics) with propofol or alfaxalone than with tiletamine-zolazepam but did not differ between tiletamine-zolazepam and ketamine-diazepam treatments. Anesthetic episode number and ETISO had no effect on extubation time or recovery score. Intrarater and interrater correlations for recovery scores were excellent.
CONCLUSIONS AND CLINICAL RELEVANCE Recovery of healthy dogs from anesthesia with isoflurane after induction with tiletamine-zolazepam was uncomplicated and had characteristics comparable to those observed following induction with ketamine-diazepam. However, recovery characteristics were improved when anesthesia was induced with propofol or alfaxalone.
Procedure—Llamas were allocated to 1 of 3 groups
(3 llamas/group). Fentanyl patches (each providing
transdermal delivery of 75 µg of fentanyl/h) were
placed on shaved areas of the antebrachium of all llamas.
In group 1, llamas were treated with 1 patch
(anticipated fentanyl dosage, 75 µg/h). In group 2, llamas
were treated with 2 patches (anticipated fentanyl
dosage, 150 µg/h). In group 3, llamas were treated
with 4 patches (anticipated fentanyl dosage,
300 µg/h). For each llama, the degree of sedation was
assessed by use of a subjective scoring system and a
blood sample was collected for determination of
serum fentanyl concentration at 12, 24, 36, 48, 60,
and 72 hours after patch placement.
Results—Following the placement of 4 patches,
mean ± SD serum fentanyl concentration in group 3
llamas reached 0.3 ± 0.08 ng/mL within 12 hours. This
concentration was sustained for 72 hours. In group 2,
application of 2 patches provided inconsistent results;
in group 1, application of 1 patch rarely provided measurable
serum fentanyl concentrations. No llamas
became sedated at any time.
Conclusions and Clinical Relevance—Results suggest
that application of four 75 µg/h fentanyl patches
provides consistent, sustained serum fentanyl concentrations
without sedation in llamas. However, the
serum concentration of fentanyl that provides analgesia
in llamas is not known. (Am J Vet Res
OBJECTIVE To compare effects of tiletamine-zolazepam, alfaxalone, ketamine-diazepam, and propofol for anesthetic induction on cardiorespiratory and acid-base variables before and during isoflurane-maintained anesthesia in healthy dogs.
ANIMALS 6 dogs.
PROCEDURES Dogs were anesthetized with sevoflurane and instrumented. After dogs recovered from anesthesia, baseline values for cardiorespiratory variables and cardiac output were determined, and arterial and mixed-venous blood samples were obtained. Tiletamine-zolazepam (5 mg/kg), alfaxalone (4 mg/kg), propofol (6 mg/kg), or ketamine-diazepam (7 and 0.3 mg/kg) was administered IV in 25% increments to enable intubation. After induction (M0) and at 10, 20, 40, and 60 minutes of a light anesthetic plane maintained with isoflurane, measurements and sample collections were repeated. Cardiorespiratory and acid-base variables were compared with a repeated-measures ANOVA and post hoc t test and between time points with a pairwise Tukey test.
RESULTS Mean ± SD intubation doses were 3.8 ± 0.8 mg/kg for tiletamine-zolazepam, 2.8 ± 0.3 mg/kg for alfaxalone, 6.1 ± 0.9 mg/kg and 0.26 ± 0.04 mg/kg for ketamine-diazepam, and 5.4 ± 1.1 mg/kg for propofol. Anesthetic depth was similar among regimens. At M0, heart rate increased by 94.9%, 74.7%, and 54.3% for tiletamine-zolazepam, ketamine-diazepam, and alfaxalone, respectively. Tiletamine-zolazepam caused higher oxygen delivery than propofol. Postinduction apnea occurred in 3 dogs when receiving alfaxalone. Acid-base variables remained within reference limits.
CONCLUSIONS AND CLINICAL RELEVANCE In healthy dogs in which a light plane of anesthesia was maintained with isoflurane, cardiovascular and metabolic effects after induction with tiletamine-zolazepam were comparable to those after induction with alfaxalone and ketamine-diazepam.
Objective—To determine the minimum alveolar concentration
(MAC) of sevoflurane in spontaneously
breathing llamas and alpacas.
Animals—6 healthy adult llamas and 6 healthy adult
Procedure—Anesthesia was induced with sevoflurane
delivered with oxygen through a mask. An endotracheal
tube was inserted, and a port for continuous
measurement of end-tidal and inspired sevoflurane
concentrations was placed between the endotracheal
tube and the breathing circuit. After equilibration at an
end-tidal-to-inspired sevoflurane concentration ratio
> 0.90 for 15 minutes, a 50-Hz, 80-mA electrical stimulus
was applied to the antebrachium until a response
was obtained (ie, gross purposeful movement) or for
up to 1 minute. The vaporizer setting was increased or
decreased to effect a 10 to 20% change in end-tidal
sevoflurane concentration, and equilibration and stimulus
were repeated. The MAC was defined as the
mean of the lowest end-tidal sevoflurane concentration
that prevented a positive response and the highest
concentration that allowed a positive response.
Results—Mean ± SD MAC of sevoflurane was 2.29 ±
0.14% in llamas and 2.33 ± 0.09% in alpacas.
Conclusions and Clinical Relevance—The MAC of
sevoflurane in llamas and alpacas was similar to that
reported for other species. (J Am Vet Med Assoc