The use of xylazine, ketamine, and isoflurane for induction and maintenance of anesthesia in ostriches (Struthio camelus).
Article Type: Report
Subject: Anesthesia (Health aspects)
Anesthesia (Research)
Isoflurane (Health aspects)
Isoflurane (Research)
Ketamine (Health aspects)
Ketamine (Research)
Authors: Sobayil, Fahd A. Al-
Ahmed, Ahmed F.
Wabel, Naser A. Al-
Thonayian, Ahmad A. Al-
Rogibah, Fars A. Al-
Fuaim, Abdulaziz H. Al-
Obaid, Abdullah O. Al-
Muzaini, Abdulaziz M. Al-
Pub Date: 06/01/2009
Publication: Name: Journal of Avian Medicine and Surgery Publisher: Association of Avian Veterinarians Audience: Academic Format: Magazine/Journal Subject: Health Copyright: COPYRIGHT 2009 Association of Avian Veterinarians ISSN: 1082-6742
Issue: Date: June, 2009 Source Volume: 23 Source Issue: 2
Topic: Event Code: 310 Science & research
Geographic: Geographic Scope: Saudi Arabia Geographic Code: 7SAUD Saudi Arabia
Accession Number: 252006949
Full Text: Abstract: To evaluate the use of xylazine/ketamine and isoflurane for the induction and maintenance of anesthesia in adult ostriches (Struthio camelus), 7 healthy adult ostriches (weight 100-130 kg) were deprived of food for 12 hours and then given an injection of xylazine (4 mg/kg IM), followed 20 minutes later by an injection of ketamine (8 mg/kg IV). After intubation, each bird was maintained on isoflurane anesthesia, and physiologic and hematologic parameters were measured. The respiratory rate and the systolic, diastolic, and mean blood pressures decreased significantly 10 minutes after delivery of isoflurane, and these decreases continued until the isoflurane was discontinued. Jaw and pedal withdrawal reflexes were useful indicators for evaluating muscle relaxation and depth of anesthesia in the ostriches while under general anesthesia. Recovery from anesthesia was relatively smooth, with minimal complications, and was complete at mean (SD) 50 [+ or -] 24 minutes after discontinuing isoflurane. From these results, we concluded that induction of anesthesia with xylazine-ketamine followed by maintenance with isoflurane produced sufficient anesthesia for performing surgical operations with relatively smooth recovery in adult ostriches.

Key words: xylazine, ketamine, isoflurane, anesthesia, avian, ostrich, Struthio camelus

Introduction

The ostrich (Struthio camelus) is the largest living bird in the world and belongs to the family Struthionidae. Ostriches originated from Africa, and ostrich farming was first reported in the 19th century in South Africa. (1) Today, ostriches are found in many regions of the world, including northern, eastern, and southern Africa, the United States, Canada, Europe, South America, Australia, and, recently, Asia. In Saudi Arabia, interest in the ostrich industry is increasing, and several new ostrich farms were recently established. Consequently, the demand for veterinary care has dramatically increased.

To provide satisfactory veterinary care, ostriches must initially be physically restrained. Handling adult ostriches is very difficult and dangerous because of their size, speed, and kicking ability. Therefore, chemical immobilization is often necessary to allow the veterinarian to conduct a safe evaluation and to provide appropriate therapeutic intervention. General anesthesia is sometimes used as a chemical immobilization procedure in adult ostriches.

Xylazine is a widely known alpha-2 agonist that is commonly used alone or in combination with ketamine to sedate, immobilize, or anesthetize ostriches. (1,2) Ketamine is a dissociative anesthetic that can be used for induction of general anesthesia in many species. (3) The combination of xylazine and ketamine (XK) is widely used to produce short-acting general anesthesia in domestic and wild animals, including ostriches. (2,4) Isoflurane is an inhalation anesthetic agent that has been used to maintain anesthesia in ostriches. (2,5,6) There are some studies of ostriches in which XK was used to induce general anesthesia and isoflurane was used to maintain anesthesia. (2) However, the anesthetic effects of these drugs have not yet been fully determined.

[FIGURE 1 OMITTED]

The purpose of this study was to evaluate the use of XK and isoflurane for induction and maintenance of anesthesia in adult ostriches.

Materials and Methods

This study was approved under the authority of Qassim University in Saudi Arabia. Seven healthy adult ostriches (weight, 100-130 kg) were used in the study. Food was withheld 12 hours before the induction of anesthesia. After covering the eyes with a hood, each ostrich was transferred from its pen to the anesthetic room by using a locally designed movable cart (Fig 1). Each bird received an injection of xylazine (4 mg/kg IM), followed 20 minutes later by an injection of ketamine (8 mg/ kg IV). The glottis was visualized while the bird was in lateral recumbency, and a cuffed endotracheal tube (size 14 mm) was passed between the arytenoid cartilages into the trachea. The anesthetized bird was connected via the endotracheal tube with a semiclosed circle rebreathing anesthetic machine (SurgiVet Foal Circuit Set, Smith Medical North America, Waukesha, WI, USA). To determine the time of the initial recovery signs from ketamine, the bird was supplied with only oxygen (3 L/min), and, immediately after the appearance of initial recovery signs (moving its head and trying to extubate the endotracheal tube), the vaporizer of isoflurane was turned on. In the first 10 minutes, isoflurane was administered at a concentration of 4% and then was maintained with a concentration of 2.5% for 50 minutes.

The onset and duration of anesthesia were recorded. Body temperature, respiratory rate, pulse rate, oxygen hemoglobin saturation (OHS), systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial blood pressure (MBP) were measured before and 20 minutes after the administration of xylazine and then every 10 minutes until recovery. Body temperature was recorded by using a digital thermometer in the cloaca, and respiratory rate was counted by watching movement of either the thoracic wall or the rebreathing bag. A pulse oximeter with a probe attached either to the caudal part of the lower beak or to the wing was used to determine the concentration of OHS and pulse rate. The SBP, DBP, and MBP were indirectly measured with an oscillometric technique, with a cuff placed around the leg in a position above the tarsus over the tibial artery. The depth of anesthesia was determined by recording various reflexes, including the palpebral, the corneal, the jaw, and the pedal withdrawal reflexes. The reflexes were categorized as absent, mild, moderate, or strong reflex (0-3).

Jugular blood samples were collected from each bird into EDTA containing Vacutainer tubes (Venoject, Leuven, Belgium) immediately before and 20 minutes after the injection of xylazine and then every 10 minutes until complete recovery. The red blood cell (RBC) and white blood cell (WBC) counts were determined by using a hemocytometer technique. The percentage of each different type of WBCs was determined by examining blood smears under the microscope. Blood smears were prepared, fixed with methanol, and stained with Giemsa stain. Hemoglobin concentration was measured by using a spectrophotometric technique.

Data were analyzed with a commercial statistical software package (SAS version 8, SAS Institute Inc, Cary, NC, USA). A repeated measures analysis of variance was used as the statistical model to evaluate the differences over time in the dependent variables, including the parameters of physiologic and hematologic functions. The Duncan test was used to calculate multiple comparisons. Results were considered significant at P < .05.

Results

The ostriches showed a slight decrease in spontaneous activity after xylazine administration. The birds became recumbent 1.2 [+ or -] 0.5 minutes (all data are shown as mean [+ or -] SD) after the administration of ketamine. The initial signs of ketamine recovery were observed 19 [+ or -] 6 minutes after its administration. All birds recovered from general anesthesia with isoflurane, and the full recovery occurred 50 [+ or -] 24 minutes after discontinuing isoflurane.

The means [+ or -] SD of physiologic parameters of ostriches induced with XK and maintained with isoflurane are shown in Table 1. The mean respiratory rate did not change after the administration of XK but decreased significantly 10 minutes after the delivery of isoflurane. This reduction continued throughout isoflurane inhalation. The mean respiratory rate gradually increased during the recovery period, but the level was significantly lower than baseline in the first 20 minutes after discontinuing the isoflurane. The SBP, DBP, and MBP levels increased after the administration of ketamine, but this increase was not significant. All MBP levels reduced significantly 10 minutes after delivery of isoflurane and continued until the end of the study. During the recovery period, these values gradually increased.

Jaw tone and pedal withdrawal reflexes were totally eliminated 3 [+ or -] 1 minutes after the administration of ketamine and continued to be absent for the 60-minute duration of anesthesia with isoflurane. Jaw tone and pedal withdrawal reflexes returned to normal 8 [+ or -] 2 minutes and 10 [+ or -] 3 minutes, respectively, after ceasing the delivery of isoflurane. Mean body temperature, pulse rate, OHS, and hematologic parameters did not change significantly from the baseline values. The stages of recovery from isoflurane anesthesia in adult ostriches are shown in Table 2. Full standing occurred 50 [+ or -] 24 minutes after the end of delivery of isoflurane.

Discussion

In this study, food was withheld from the ostriches for 12 hours before anesthesia was induced. To minimize the risk of regurgitation and aspiration, adult ratites should be deprived of food for 12 to 24 hours before induction of anesthesia. (7) Adult ostriches that are food deprived for periods longer than 24 hours may complicate the anesthetic period because of the high metabolic rate of these birds. (1) Depriving food is not recommended for ostrich chicks because of subsequent hypoglycemia that might develop during the peri-anesthetic period. (8) Ostriches were efficiently handled and transferred from one place to another by hooding them and transporting them in a movable cart.

Results of this study showed a slight decrease in spontaneous activity after xylazine administration. Similar results were reported when injecting healthy adult ostriches with xylazine at a dose of 2.2 mg/kg IM. (5) The induction of anesthesia with ketamine produced general anesthesia within 1.2 [+ or -] 0.5 minutes after its administration. Doses of [alpha.sub.2]-agonist and ketamine combinations in ostriches have varied, depending on the type of [alpha.sub.2]-agonist, the age of the bird, and the route of administration. (9-12) The doses of xylazine and ketamine used in our study were 4 mg/kg IM and 8 mg/kg IV, respectively. These doses produced safe anesthesia with good muscle relaxation in healthy adult ostriches for 19 [+ or -] 6 minutes. The administration of xylazine (2.2 mg/kg IM) followed 15 minutes later by ketamine (2.2-3.3 mg/kg IV) in ostriches has been reported as producing recumbency in 30-60 seconds, with a duration of 15-25 minutes. (1,5)

XK is not recommended as an induction combination for inhalation anesthesia because of cardiorespiratory effects. (2,8) However, we found that inducing anesthesia with ketamine and maintaining it with isoflurane produced sufficient anesthesia for performing surgery in adult ostriches with relatively smooth recovery. In this study, we postponed isoflurane delivery until the birds showed initial signs of recovery from ketamine. We did this to determine the time at which signs of initial recovery from ketamine occurred and to describe the characteristics of these signs. Generally, isoflurane is a preferred avian inhalant anesthetic because it offers rapid induction and recovery, less depression of cardiac output than other agents, and apparent absence of sensitization to myocardial-induced arrhythmias. (13,14) Isoflurane is simply exhaled for anesthetic recovery and not metabolized by the body. (15) Isoflurane produces a lower incidence of hepatotoxicity and reasonable muscle relaxation. (13,14) An induction vaporizer setting of isoflurane not exceeding 3% and a maintenance setting from 1.5% to 2% has been recommended. (16) In our study, the induction concentration of isoflurane in the vaporizer was 4%, and maintenance was 2.5%. These relatively high concentrations of isoflurane could have been avoided if the inhalant anesthesia had been used before semirecovery from the ketamine. Major complications with these concentrations were not seen.

In addition to the parameters of physiologic functions, pedal withdrawal reflex, in which the leg flexes in response to painful stimulation of the digits or pinch of the interdigital region, was a good indicator for the depth of anesthesia in the ostriches. During induction and maintenance of anesthesia, pedal withdrawal reflex was completely absent, which indicated an efficient depth of anesthesia. Jaw tone, which was completely absent during induction and maintenance of anesthesia, was used to subjectively evaluate muscle tone. Muscle tone of the neck is reported as a useful indicator of anesthetic depth in ratites. (8) The disappearance of jaw tone and pedal withdrawal reflexes after administration of ketamine and isoflurane maintenence anesthesia supports our conclusion that these reflexes in ostriches are useful indicators for evaluating muscle relaxation and depth of anesthesia, respectively. Because the eyes of the birds were completely closed during anesthesia, assessment of either palpebral or corneal reflexes in anesthetized ostriches was impractical.

A commercial rebreathing anesthetic machine for foals with a semiclosed system was appropriate to perform inhalation anesthesia in the ostriches. A size 14- to 18-mm cuffed endotracheal tube was recommended in adult ostriches (5,8); in our study, 14-mm cuffed endotracheal tubes were used. Intubation of the birds was very easy, with no need for a laryngoscope or a guide tube. The beak was opened, and the glottis was easily identified at the base of the tongue. Because the trachea of the ostrich is composed of complete cartilaginous rings, the cuff of the endotracheal tube was inflated by injecting small amounts of air (5-10 ml) into the cuff to prevent trauma to the trachea. This amount of air created an internal pressure on the trachea that was enough to prevent leakage of anesthetic gases into the environment and at the same time did not interfere with tracheal mucosal blood flow. The rate of oxygen flow used in this study was 3 L/min, which is appropriate for an adult ostrich.

The normal body temperature of ostriches varies from 37.8[degrees]C to 40.7[degrees]C, (17) and the highest normal rectal temperature measured after exercise is 46.4[degrees]C. (18) In the ostriches in this study, anesthesia by using a combination of XK for induction and isoflurane for maintenance did not cause significant changes in body temperature (Table 1: high, 40.7[degrees]C ; low, 39.8[degrees]C). Ludders et al (19) reported a moderate hyperthermia in pekin ducks (Anus domesticus) after intravenous administration of XK. In another study, Stegmann (20) reported hypothermia in 4 healthy ostriches during maintenance of anesthesia with isoflurane. However, anesthesia was induced with a combination of midazolam and ketamine.

In the ostriches in this study, the respiratory rate decreased significantly 10 minutes after isoflurane anesthesia was initiated and continued to decrease until the weaning of inhalation anesthesia. This is a possible result of the higher concentrations of isoflurane used in the present study compared with the previously published concentrations. (16) A gradual increase in the respiratory rate was seen during the recovery period. In red-tailed hawks (Buteo jamaicensis) (21) and pekin ducks, (19) a XK combination injected intravenously produced respiratory depression. In the present study, the combination of XK did not significantly affect the respiratory rate in ostriches. However, xylazine was given intramuscularly 20 minutes before the intravenous administration of ketamine, and the doses of XK combination were different from the previous reports. In ostriches, the respiratory rate was reported to decrease significantly during the surgical plane of anesthesia to a level above 8 breaths/min. (8) In our study, respiratory rates were relatively rapid, which was reported in ratites anesthetized with isoflurane? (22,23) Results of our study showed that controlled ventilation might be recommended during anesthesia of ostriches with isoflurane.

Pulse oximetry is a noninvasive procedure for measuring pulse rate and the percentage of OHS in the blood. Probes were placed on the wings of unanesthetized birds and on the intermandibular tissue of anesthetized birds. This provided a high success rate of pulse oximetry reading. Values for OHS did not change over time in the blood of anesthetized ostriches. We noticed that the values of OHS were relatively high (above 90%) even when the respiratory rate of the bird was significantly depressed. We could not determine whether these values were accurate. A study by Cornick-Seahorn (8) reported a limited effect when placing the probe on the lower beak.

The pulse rate of the anesthetized ostriches did not significantly change during the anesthesia. A similar result was reported in 4 healthy ostriches premedicated with midazolam-ketamine and maintained with isoflurane. (20) In general, bradycardia attributable to decreased sympathetic activity and enhanced vagal activity is a characteristic response to xylazine injection. (24) However, in the present study, the pulse rate did not significantly change from normal values after the administration of xylazine. A similar result was reported in pekin ducks. (19) Degernes et al (21) reported bradycardia in red-tailed hawks anesthetized intravenously with a combination of XK. In that study, the XK combination was given intravenously, with different doses from those used in our study. A nonsignificant increase in the pulse rate was seen in our study 30 minutes after the delivery of isoflurane. Pulse rate has been reported to increase during isoflurane anesthesia in ostriches. (23) Results of our study showed that use of anticholinergic drugs might not be necessary in ostriches. Anticholinergic therapy is indicated when the pulse rate drops below 30-35 beats/min or if a precipitous decrease from baseline rate occurs. (2) In addition to pulse rate, pulse quality and mucous membrane color should affect the decision to administer an anticholinergic drug. (8)

When measuring the blood pressure, the cuff was placed over the tibial artery on the leg above the tarsus. Blood pressure was relatively easy to measure with this technique. Covering the eyes and restraining the bird inside the movable cart allowed the researchers to successfully measure the parameters of physical function, including blood pressure on an awake bird. A significant reduction in the values of SBP, DBP, and MBP was seen 10 minutes after the delivery of isoflurane, and these values gradually increased during the recovery period. However, during the recovery period, values for SBP, DBP, and MBP continued to be significantly lower than baseline values. Isoflurane has a vasodilating effect, which reduces arterial blood pressure. (25) The relatively higher concentrations of isoflurane used in our study might have been a factor in the significant decrease in the arterial blood pressure. Matthews et al (26) reported premature ventricular contractions and apparent hypertension in adult ostriches anesthetized with isoflurane. However, a light plane of anesthesia or hypercapnia may have masked the characteristic cardiovascular effect of isoflurane in that study. In general, values of arterial blood pressure in ostriches are higher than those recorded for most mammalian species. (2) In our study, the values of SBP, DBP, and MBP ranged from 145 to 215, 86 to 106, and 115 to 144 mm Hg, respectively, during maintenance anesthesia with isoflurane.

The right jugular vein was used for collecting blood samples from the ostriches. In ostriches, the right jugular vein is very movable and usually approached on the dorsolateral aspect of the neck. (9) In addition to the right jugular vein, the left jugular vein, the brachial vein, (27) and the radial and ulnar veins (9) can be used for collecting blood samples from adult ostriches. Results of the CBC counts showed no significant changes during the period of anesthesia. Although values of RBCs and hemoglobin decreased during the delivery of isoflurane, changes were not significant.

A complicated recovery was reported in adult ostriches anesthetized for 45 minutes with isoflurane. (27) It has been reported that ostriches should be positioned in sternal recumbency and the head should be supported until the bird is able to maintain normal head posture,s A full recovery time of 60 minutes was reported in an ostrich anesthetized with a midazolam-ketamine combination and maintained with isoflurane. (20) In the present study, the ostriches were allowed to recover in a small, semidarkened, padded room. The birds were transferred to the recovery room and left to recover without any restraint or manual assistance. Full recovery occurred 50 [+ or -] 24 minutes after isoflurane delivery was terminated (Table 2). Recovery started within 8 minutes after discontinuing the delivery of inhalation anesthesia and was characterized by movement of the head and neck, attempts to extubate the endotracheal tube, and then movement of the legs. About 22 minutes (all times are mean) after the termination of anesthesia, the birds were able to sit sternally. At approximately 24 minutes after the cessation of anesthesia, the birds raised their heads and necks, and, at 29 minutes, they were able to sit on their heels. The first attempt to stand was at 31 minutes, and successful standing was at 50 minutes after discontinuing anesthesia. We concluded that anesthetic induction with XK followed by maintenence with isoflurane produces sufficient anesthesia for performing surgical operations with minimal complications and relatively smooth recovery in adult ostriches.

Acknowledgments: We thank Dr O. H. Omer for technical assistance. Special thanks to the Arabian Integral Ministration Company for the donation of the ostriches.

References

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(3.) Hartsfield SM. Advantages and guidelines for using ketamine for induction of anesthesia. Vet Clin North Am Small Anim Pract. 1992;22:266-267.

(4.) Gandini GCM, Keffen RH, Burroughs REJ, Ebedes H. An anaesthetic combination of ketamine, xylazine, and alphaxalone-alphadolone in ostriches (Struthio camelus). Vet Rec. 1986;118: 729-730.

(5.) Lin HC, Ko JCH. Anesthetic management of ratites. Compend Contin Educ Practicing Vet. 1997; 19(suppl 4):S127-S132.

(6.) Lin HC, Todhunter PG, Powe TA, Ruffin DC. Use of xylazine, butorphanol, tiletamine-zolazepam, and isoflurane for induction and maintenance of anesthesia in ratites. J Am Vet Med Assoc. 1997; 210:244-248.

(7.) Ostrowski S, Ancrenaz M. Chemical immobilization of red-necked ostriches (Struthio camelus) under field conditions. Vet Rec. 1995; 136:145-147.

(8.) Cornick-Seahorn JL. Anesthesiology of ratites. In: Tully TNJr, Shane SM, eds. Ratite Management, Medicine and Surgery. Malabar, FL: Krieger Publishing Co; 1996:79-94.

(9.) Gilsleider EF. Anesthesia and surgery of ratites. Vet Clin North Am Food Anim Pract. 1998;14:503-524.

(10.) Paul-Murphy J, Fialkkowski J. Injectable anesthesia and analgesia of birds. International Veterinary Information Service. www.ivis.org/advances/ Anesthesia_Gleed/paul/chapter.asp?LA=1. Updated August 5, 2001. Accessed May 12, 2009.

(11.) Marx KL. Therapeutic agents. In: Harrison GJ, Lightfoot TL, eds. Clinical Avian Medicine. Vol I. Palm Beach, FL: Spix Publishing; 2006:214-342.

(12.) De Lucas JJ, Rodriguez C, Marin M, et al. Pharmacokinetics of intramuscular ketamine in young ostriches premedicated with romifidine. J Vet Med. 2007;54:48-50.

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(16.) Heard DJ. Anesthesia and analgesia. In: Altman RB, Clubb SL, Dorrestein GM, Quesenberry K, eds. Avian Medicine and Surgery. Philadelphia, PA: WB Saunders; 1997:807-827.

(17.) Huchzermeyer FW. Ostrich Diseases. Onderstepoort, Republic of South Africa: Agricultural Research Council, Onderstepoort Veterinary Institute; 1994:77.

(18.) Taylor CR, Dmiel R, Fedak M, Schmidt-Nielsen K. Energetic cost of running and heat balance in a large bird, the rhea. Am J Physiol. 1971;221:597-601.

(19.) Ludders JW, Rode J, Mitchell GS, Nordheim EV. Effects of ketamine, xylazine, and a combination of ketamine and xylazine in Pekin ducks. Am J Vet Res. 1989;50:245-249.

(20.) Stegmann GF. Observations on the use of midazolam-ketamine for induction of anesthesia in four ostriches. S Afr J Wildl Res. 2000;20:58-61.

(21.) Degernes LA, Kreeger TJ, Mandsager R, Redig PT. Ketamine-xylazine anesthesia in red-tailed hawks with antagonism by yohimbine. J Wildl Dis. 1988;24:322-326.

(22.) Jensen J. Ratite anesthesia and surgery. Proc Ostrich Med Semin Vet. 1990:6-7.

(23.) Kimminau KM. Introducing the ostrich. Vet Tech. 1993;14:459-467.

(24.) Greene SA, Thurmon JC. Xylazine: a review of its pharmacology and use in veterinary medicine. J Vet Pharmacol Ther. 1988;11:295-313.

(25.) Eger EI. Isoflurane: a review. Anesthesiology. 1981;55:559-576.

(26.) Matthews NS, Burba D J, Cornick JL. Premature ventricular contractions and apparent hypertension during anesthesia in an ostrich. J Am Vet Med Assoc. 1991;198:1959-1961.

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Fahd A. Al-Sobayil, PhD, Ahmed F. Ahmed, PhD, Naser A. Al-Wabel, PhD, Ahmad A. Al-Thonayian, BVSc, Fars A. Al-Rogibah, BVSc, Abdulaziz H. Al-Fuaim, BVSc, Abdullah O. Al-Obaid, BVSc, and Abdulaziz M. Al-Muzaini, BVSc

From the Department of Veterinary Medicine, College of Agriculture and Veterinary Medicine, Qassim University, Buraydah 51452, PO Box 6622, Al-Qassim, Saudi Arabia.
Table 1. Physiologic parameters (mean [+ or -] SD) of ostriches
(n = 7) anesthetized with xylazine, ketamine, and isoflurane.

Time (min)    BT ([degrees]C)      RR (breaths/min)

    0        40.2 [+ or -] 0.2   34.0 [+ or -] 8.4
    20       40.1 [+ or -] 0.1   34.3 [+ or -] 4.1
    30       40.1 [+ or -] 0.2   39.6 [+ or -] 5.6
    40       40.1 [+ or -] 0.2   38.0 [+ or -] 5.8
    50       40.1 [+ or -] 0.1   24.6 [+ or -] 7.2 (a)
    60       40.1 [+ or -] 0.2   24.6 [+ or -] 4.7 (a)
    70       39.8 [+ or -] 0.5   22.5 [+ or -] 6.1 (a)
    80       40.1 [+ or -] 0.2   21.1 [+ or -] 5.T (a)
    90       40.7 [+ or -] 0.3   21.0 [+ or -] 6.6 (a)
   100       39.8 [+ or -] 0.3   24.4 [+ or -] 8.2 (a)
   110       39.9 [+ or -] 0.4   25.7 [+ or -] 3.5 (a)
   120       40.2 [+ or -] 0.3   31.3 [+ or -] 3.2
   130       40.1 [+ or -] 0.3   31.3 [+ or -] 5.4
   140       40.2 [+ or -] 0.3   33.4 [+ or -] 8.2

Time (min)     PR (beats/min)          OHS (%)

    0        66.6 [+ or -] 5.6    97.6 [+ or -] 0.6
    20       60.3 [+ or -] 4.1    97.3 [+ or -] 2.1
    30       65.6 [+ or -] 5.2    97.3 [+ or -] 2.2
    40       55.3 [+ or -] 9.5    97.6 [+ or -] 1.5
    50       51.0 [+ or -] 6.2    92.4 [+ or -] 1.7
    60       50.0 [+ or -] 6.2    91.0 [+ or -] 1.0
    70       60.0 [+ or -] 8.2    90.4 [+ or -] 1.8
    80       63.4 [+ or -] 13.7   92.3 [+ or -] 1.6
    90       62.7 [+ or -] 17.0   93.4 [+ or -] 2.6
   100       64.4 [+ or -] 14.1   90.2 [+ or -] 3.5
   110       67.6 [+ or -] 11.7   90.3 [+ or -] 1.2
   120       65.0 [+ or -] 10.1   93.0 [+ or -] 1.0
   130       65.4 [+ or -] 10.2   95.3 [+ or -] 1.2
   140       63.6 [+ or -] 7.3    96.7 [+ or -] 2.2

Time (min)         SBP (mm Hg)              DBP (mm Hg)

    0        208.0 [+ or -] 16.1       121.0 [+ or -] 15.2
    20       197.6 [+ or -] 15.1       143.6 [+ or -] 25.4
    30       217.3 [+ or -] 23.5       141.1 [+ or -] 26.3
    40       215.0 [+ or -] 18.0       1412 [+ or -] 22.5
    50       145.6 [+ or -] 16.1 (a)   90.0 [+ or -] 18.5 (a)
    60       149.3 [+ or -] 16.5 (a)   86.2 [+ or -] 16.2 (a)
    70       151.0 [+ or -] 9.8 (a)    89.0 [+ or -] 16.4 (a)
    80       165.1 [+ or -] 4.2 (a)    90.0 [+ or -] 16.0 (a)
    90       163.5 [+ or -] 25.1 (a)   88.3 [+ or -] 20.1 (a)
   100       157.4 [+ or -] 15.2 (a)   91.7 [+ or -] 11.2 (a)
   110       167.6 [+ or -] 21.6 (a)   94.0 [+ or -] 9.5 (a)
   120       173.5 [+ or -] 26.6 (a)   98.7 [+ or -] 10.4 (a)
   130       169.3 [+ or -] 29.7 (a)   103.4 [+ or -] 13.1
   140       175.4 [+ or -] 16.8 (a)   106.3 [+ or -] 14.5

Time (min)         MBP (mm Hg)

    0        162.3 [+ or -] 15.5
    20       170.6 [+ or -] 20.1
    30       176.6 [+ or -] 24.5
    40       176.3 [+ or -] 18.5
    50       117.3 [+ or -] 16.5 (a)
    60       115.5 [+ or -] 15.7 (a)
    70       119.4 [+ or -] 13.6 (a)
    80       126.0 [+ or -] 4.6 (a)
    90       125.3 [+ or -] 15.4 (a)
   100       123.7 [+ or -] 14.5 (a)
   110       131.7 [+ or -] 10.1
   120       137.6 [+ or -] 6.1
   130       141.4 [+ or -] 11.7
   140       144.3 [+ or -] 13.9

Abbreviations: BT indicates body temperature; RR, respiratory
rate; PR, pulse rate; OHS, oxygen hemoglobin saturation; SBP,
systolic blood pressure; DBP, diastolic blood pressure; MBP,
mean blood pressure.

(a) Value significantly different from 0 min value (base value)
at P < .05.

Table 2. Stages of recovery after discontinuing
isoflurane in adult ostriches (n = 7) anesthetized with
xylazine, ketamine, and isoflurane.

                                  Time after discontinuing
Position of the bird       isoflurane (mean [+ or -] SD) (min)
Moving head and neck,
  trying to extubate the
  endotracheal tube                   8 [+ or -] 2
Moving legs                          10 [+ or -] 3
Sitting on sternum                   22 [+ or -] 3
Raising head and neck                24 [+ or -] 3
Sitting on heels                     29 [+ or -] 6
First attempt to stand               31 [+ or -] 5
Full standing                        50 [+ or -] 24
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