The effect of induction with propofol or ketamine and diazepam on quality of anaesthetic recovery in dogs.

OBJECTIVE: To evaluate the quality of recovery in dogs undergoing elective orthopaedic surgery induced with either propofol or a combination of ketamine and diazepam. MATERIALS AND METHODS: Sixty client-owned dogs undergoing single-limb elective orthopaedic procedures were enrolled. Dogs were randomly assigned to receive induction with propofol (4 mg/kg) (group P) or ketamine (5 mg/kg) with diazepam (0.25 mg/kg) (group KD) to which all scorers were blinded. The recovery monitoring period lasted for 1 hour following extubation. The recovery period was video-recorded for blinded scoring at a later time. Scoring for quality of recovery was carried out using three different systems (lower numbers=better quality): a simple descriptive scale (1 to 5), a visual analogue scale (0 to 10 cm) and a numeric rating scale (0 to 10). Videos were reviewed by three ACVAA board-certified anaesthesiologist raters. RESULTS: Five dogs were deemed to be ineligible. The mean (±SD) duration of anaesthesia was 260.4 ±57.84 minutes in group KD and 261.1 ±51.83 minutes in group P. There was no difference between groups for time to extubation, head lift or sternal recumbency. The number of dogs having a recovery that was scored overall as bad (mean simple descriptive scale > 4, mean visual analogue scale or numeric rating scale > 5) was not different between groups. Dogs in group KD had significantly lower scores than group P dogs (simple descriptive scale P=0.01, numeric rating scale P=0.03, visual analogue scale P=0.03). CLINICAL SIGNIFICANCE: Induction with ketamine and diazepam resulted in a smoother recovery from anaesthesia than induction with propofol.

Assessment of v-gel supraglottic airway device placement in cats performed by inexperienced veterinary students.

Endotracheal intubation has been associated with several complications in cats. The v-gel supraglottic airway device (SGAD) has been developed to adapt to the unique oropharynx of the cat and to overcome these complications. Thirty-three cats were randomly assigned to receive an endotracheal tube (ETT group) or a v-gel SGAD (v-gel group) after induction of general anaesthesia. Third year veterinary students without previous clinical experience placed these devices under direct supervision of an anaesthesiologist. Amount of propofol, number of attempts, time required to secure the airway, leakage around the device, signs of upper airway discomfort and food consumption were compared between the two groups. The v-gel group required less propofol (P=0.03), less time (P<0.01) and fewer attempts (P<0.01) to secure the cats' airway. The incidence of leakage was lower for the v-gel group immediately after placement of the device (P<0.01) and 60 minutes after induction of general anaesthesia (P=0.04). Cats that received the v-gel SGAD presented a lower incidence of upper airway discomfort immediately after the device was removed (P=0.03) and recorded a higher food consumption score (P=0.03). The v-gel SGAD is a feasible way to secure the airway of healthy cats when performed by inexperienced personnel.

The effect of midazolam on the recovery quality, recovery time and the minimum alveolar concentration for extubation in the isoflurane-anesthetized pig.

There are no reported studies evaluating the effect of midazolam on recovery quality, recovery time or minimum alveolar concentration (MAC) at which extubation occurs (MAC extubation). Our hypotheses were that midazolam administered prior to recovery would decrease MAC extubation, prolong recovery time but provide a smoother recovery. Sixteen Yorkshire pigs were anesthetized with isoflurane for approximately 5 h. The end-tidal isoflurane concentration was then stabilized at 1.4% for 20 min. Pigs were randomly assigned to receive midazolam or saline. The vaporizer was decreased by 10% every 10 min until extubation. Pigs were declared awake by a blinded observer and were assigned a recovery score by the same observer. Mean MAC extubation was not significantly different for pigs receiving saline prior to recovery compared with those pigs receiving midazolam. The overall mean MAC extubation for both groups was 0.6 ± 0.4 vol%. Time to extubation was not significantly longer with midazolam (124 ± 36 min) compared with the saline group (96 ± 61 min; P = 0.09). Recovery score was not significantly different between groups (midazolam, 0.86 ± 1.1; saline 0.5 ± 0.5; P = 0.26). In conclusion, midazolam did not affect MAC extubation. There was no advantage of administering midazolam in the recovery period when performing step-down titration of isoflurane anesthesia.

A multisite case report on the clinical use of sevoflurane in dogs.

The purpose of this report was to evaluate the clinical safety and efficacy of sevoflurane as an inhalant anesthetic in dogs. Subjective and objective data from 196 clinical cases utilizing sevoflurane as the maintenance anesthetic was collected at three sites. After preanesthetic evaluation, the attending anesthesiologist assigned the dogs to one of the following six anesthetic protocols: protocol 1, oxymorphone premedication and thiopental induction; protocol 2, oxymorphone/acetylpromazine premedication and thiopental induction; protocol 3, xylazine/butorphanol premedication and thiopental induction; protocol 4, opioid premedication and propofol induction; protocol 5, optional premedication and mask induction with sevoflurane in oxygen; and protocol 6, optional premedication and optional induction. The average quality of induction, maintenance, and recovery was good to excellent in all protocols. The three most common side effects during maintenance and recovery were hypotension, tachypnea, and apnea. Sevoflurane produces anesthesia in dogs comparable to the other inhalation anesthetics currently used (i.e., halothane and isoflurane) for diagnostic or therapeutic procedures.

Use of a hyaluronate membrane for jejunal anastomosis in horses.

OBJECTIVE: To compare the outcomes of double-layer inverting anastomosis (DIA), single-layer anastomosis (SLA), and single-layer anastomosis combined with a hyaluronate membrane (SLA+HA-membrane) with respect to stomal diameter, adhesion formation, surgery time, and anastomotic healing in horses. ANIMALS: 18 adult horses. PROCEDURE: Midline celiotomy and end-to-end anastomoses were performed. In control horses (n = 6), DIA was performed; in treated horses, SLA was performed (6) or SLA+HA-membrane was performed (6). Horses were euthanatized 21 days after surgery. Abdominal adhesions were evaluated grossly and histologically. Stomal diameters were measured ultrasonographically and compared with adjacent luminal diameters. Anastomotic healing was evaluated histologically for fibrosis and inflammation, tissue alignment, and inversion. Surgery times were recorded for the anastomotic procedure and compared among groups. RESULTS: There were significantly more adhesions in the SLA group, compared with the DIA and SLA+HA-membrane groups. Reduction in stomal diameters in the DIA group was significantly greater than the SLA and SLA+HA-membrane groups. Surgery times for the DIA group were significantly greater than the SLA and SLA+HA-membrane groups. Histologic findings of fibrosis, inflammation, and mucosal healing were similar among groups. There was significant tissue inversion in the DIA group, compared with the 2 treatment groups. Tissue alignment was not different among groups. CONCLUSIONS AND CLINICAL RELEVANCE: Use of a SLA+HA-membrane was an effective small intestinal anastomotic technique. This technique was faster to perform and resulted in a larger stomal diameter, compared with the DIA technique and significantly fewer perianastomotic adhesions, compared with the SLA technique.

Sevoflurane anesthesia in psittacines.

Duration of anesthesia onset (time to intubation) and recovery (time to extubation, sternal and standing) and quality of recovery were compared for sevoflurane and isoflurane in 10 adult psittacines. Both agents were initially administered at an equal volume percentage (2%) rather than at equal minimum alveolar concentrations (MACs), therefore the initial concentration was above the isoflurane MAC for dogs and birds (1.3%) but below the sevoflurane MAC for dogs (2.3%). The time to intubation was significantly longer with sevoflurane because of initially delivering the sevoflurane below suspected MAC for birds. Although recovery times (time to extubation, sternal, and standing) were not significantly different, birds recovering from sevoflurane were less ataxic. Sevoflurane is a suitable inhalant agent for use in these psittacines and merits further study.

Changes in cortisol concentration in response to stress and postoperative pain in client-owned cats and correlation with objective clinical variables.

OBJECTIVE: To identify clinical variables that indicate postoperative pain in cats after ovariohysterectomy in a veterinary hospital setting. ANIMALS: 40 cats. PROCEDURE: Cats were anesthetized and ovariohysterectomized by senior veterinary students. Butorphanol (0.1 mg/kg [n = 20] or 0.3 mg/kg [20] of body weight) was administered IM after surgery. Blood samples were obtained before, during, and after the anesthetic period for measurements of PCV and blood glucose and cortisol concentrations. Clinical variables measured included heart rate, systolic blood pressure, respiratory rate, and rectal temperature. Data for these variables were compared with changes in cortisol concentrations and with similar data-which was used as historical control data-obtained from 20 cats in another study (10 that had been ovariohysterectomized but had not received butorphanol and 10 that had only been anesthetized). RESULTS: Surgical durations were longer in this study, and cats had higher cortisol concentrations, compared with historical control cats. Objective clinical variables did not consistently correlate with changes in cortisol concentration. CONCLUSIONS: Cortisol concentration increased in response to surgical stress and pain. This response was greater in cats in which duration of surgery was longer. CLINICAL RELEVANCE: The objective clinical variables evaluated in this study were not consistent indicators of pain in an uncontrolled, clinical situation.

Anesthetic considerations for laser, laparoscopy, and thoracoscopy procedures.

Laser surgery and laparoscopy are two relatively new surgical techniques gaining popularity in veterinary medicine, which require special consideration when being performed on the anesthetized patient. For laser surgery, consideration must be given to the possibility of atmospheric contamination, inappropriate energy transfer, eye injury, perforation of a vessel or anatomic structure, perforation of the endotracheal tube, and fire. The primary concern with laparoscopy and thoracoscopy is the creation of a pneumoperitoneum or pneumothorax, which can result in (1) hypercarbia and inadequate ventilation, (2) poor cardiac output and systemic blood pressure, and (3) gas embolism. To minimize complications, patients should be placed on positive pressure ventilation, be well hydrated before and during the procedure, and be thoroughly monitored (ECG, capnography, pulse oximetry.

Anesthesia in a Baird's tapir (Tapirus bairdii).

A Baird's tapir (Tapirus bairdii) was satisfactorily immobilized on two occasions with i.m. detomidine (0.065-0.13 mg/kg) and butorphanol (0.13-0.2 mg/kg). On the second occasion, anesthesia was induced by i.v. administration of ketamine (2.2 mg/kg). Twenty minutes later, endotracheal intubation was performed after an additional i.v. injection of ketamine (1.5 mg/kg). Anesthesia was maintained with isoflurane, which provided excellent conditions for radiology and surgery. Anesthesia was associated with hypoxemia when the tapir was allowed to breathe air and with hypoventilation. Mean arterial pressure remained satisfactory. No antagonist drugs were administered, and recovery from anesthesia was rapid and smooth.

Cardiorespiratory and anesthetic effects of propofol and thiopental in dogs.

OBJECTIVE: To compare cardiorespiratory and anesthesia effects of IV administered propofol and thiopental in dogs. ANIMALS: 6 healthy mixed-breed dogs. PROCEDURE: Each dog was anesthetized with isoflurane, then a thermistor catheter was inserted in the pulmonary artery. After a minimum of 2.5 hours of recovery, a catheter was placed in a cephalic vein for administration of lactated Ringer's solution and drugs. Propofol (8 mg/kg of body weight) or thiopental (19.4 mg/kg) was administered to each dog in a randomized crossover design study. All dogs were intubated and allowed to breathe 100% oxygen spontaneously. Heart rate and rhythm; systolic, diastolic, and mean arterial blood pressures; respiratory rate; end-tidal carbon dioxide concentration; tidal volume; and reflexes (toe web pinch, palpebral response, and jaw tone) were measured before and every 2 minutes for the first 10 minutes, then at 15, 30, and 60 minutes after drug administration. Cardiac output was determined at 0, 2, 6, 10, 15, 30, and 60 minutes, and blood samples were collected at 0, 2, 10, and 30 minutes. Time to endotracheal extubation, head lift, and ability to sit sternally and walk unaided were recorded. RESULTS: 3 of 6 dogs in each group were apneic after drug administration. Reflexes were decreased similarly for both anesthetic agents, but were not completely lost. Time to sternal position and walking unaided were significantly shorter in response to propofol. CONCLUSION: Anesthesia was rapid; however, respiratory depression and apnea were major adverse effects associated with propofol and thiopental. Propofol has the advantage of inducing rapid, coordinated anesthesia recovery.

Use of partial prostatectomy for treatment of prostatic abscesses and cysts in dogs.

OBJECTIVE: To determine whether dogs had prostatic disease, urinary incontinence, or urinary tract infection 1 year after partial prostatectomy to treat prostatic abscesses and cysts. DESIGN: Prospective study. ANIMALS: 20 male dogs with prostatic abscesses or cysts. Fifteen dogs had evidence of urinary tract infection. Only 8 dogs urinated normally; the remainder dribbled, had obstructions, or required medical treatment. PROCEDURE: Partial prostatectomy was performed on each dog. Sexually intact dogs (n = 12) also were castrated. RESULTS: None of the dogs had return of prostatic cystic enlargement or clinical signs of prostatic disease during the first year after surgery. Two dogs were euthanatized within 1 year after surgery, with 1 dog having prostatic enlargement and adenocarcinoma and 1 dog having unrelated lymphosarcoma. Fifteen dogs were continent. The remaining 5 dogs urinated normally but had intermittent and minor incontinence. Eleven dogs had no signs of infection 1 year after surgery, 5 had pyuria or positive urine bacteriologic culture results, 2 did not have urinalysis performed, and 2 were euthanatized. CLINICAL IMPLICATIONS: Dogs with severe prostatic abscesses or cysts and infections can be successfully treated by partial prostatectomy with an ultrasonic surgical aspirator and castration, resulting in long-term disease resolution. Although most dogs with severe prostatic disease do not urinate normally before surgery, nearly all dogs resume normal micturition after partial prostatectomy. Postoperative results of partial prostatectomy appear to be better than those of previous drainage techniques for treatment of prostatic cavitary disease.

Indicators of postoperative pain in cats and correlation with clinical criteria.

OBJECTIVE: To identify clinical indicators that may help identity postoperative pain in cats after ovariohysterectomy. ANIMALS: Healthy, laboratory animal source cats. PROCEDURE: Clinical indicators of pain were identified, and relief from pain in response to butorphanol was studied in 5 groups of cats. 10 cats had 1 hour of general anesthesia only, followed by recovery without additional medication. 10 cats had general anesthesia and ovariohysterectomy, followed by recovery without additional medication. 10 cats had general anesthesia, ovariohysterectomy, and postoperative administration of 0.1 mg of butorphanol/kg of body weight. Another 10 cats had general anesthesia, ovariohysterectomy, and postoperative administration of 0.3 mg butorphanol/kg. 10 cats received 0.1 mg of butorphanol/kg, IM, only. Samples and recorded data were obtained before, during, and after the anesthesia period. Clinical variables measured included heart rate, blood pressure, respiratory rate, rectal temperature, PCV, and blood glucose concentration. Results were compared with changes in norepinephrine, epinephrine, and cortisol concentrations. RESULTS: Cats that did not receive analgesics had higher cortisol concentration than did cats without surgery and cats that received butorphanol after surgery. Systolic blood pressure measured by ultrasonic Doppler was found to be predictive of cortisol concentration, using a multiple linear regression model. CONCLUSIONS: Cortisol concentration increased in response to surgical stress and pain, and this increase was diminished by use of butorphanol. CLINICAL RELEVANCE: Systolic blood pressure was the best clinical predictor of postoperative pain.

Nasotracheal intubation in calves.

Nasotracheal intubation can be accomplished in calves by use of a silicone nasotracheal tube of a Murphy design. For intubation, the calf's head and neck should be extended to facilitate tube passage through the naris into the ventral meatus and then through the larynx into the trachea. Preanesthetic medication may assist in tube passage by decreasing the alertness of the calf and decreasing the ability of the calf to swallow the tube into the esophagus. Nasotracheal intubation allows the inhalant anesthetic agent to be delivered with minimal room pollution and less stress to the calf. It would be useful for oral surgery when an orotracheal tube would obstruct the surgical site.

Butorphanol does not reduce the minimum alveolar concentration of halothane in dogs.

This study evaluated the effect of butorphanol tartrate, a synthetic opioid agonist-antagonist, on halothane minimum alveolar concentration (MAC) in dogs. Baseline halothane MAC was determined in each of six dogs. Butorphanol was administered and halothane MAC was redetermined. Each dog received butorphanol at 0.2, 0.4, and 0.8 mg/kg intravenously at 1 week intervals. Heart rate and arterial blood pressure decreased after butorphanol administration, but returned to baseline by 50 minutes. There was little effect on respiratory parameters. A halothane-sparing effect was not noted with any butorphanol dose.

Endotracheal tube displacement during cervical manipulation in the dog.

A retrospective study was performed to identify positional changes of endotracheal tubes (ETT) during cervical spine radiography in 153 dogs. Three neck positions were identified: traction, hyperextension, and flexion. A properly placed ETT was defined as having the caudal tip of the tube located between the caudal half of the fourth cervical (C) vertebra (C4) and the caudal half of C7. In the traction position, before neck flexion and extension, the caudal tip of 13% of ETT were located caudal to C7, and one tube was in the endobronchial position at the seventh thoracic (T) vertebra (T7). In the hyperextended position, 60% of ETT moved cranially. The average distance moved was 0.6 vertebral spaces. In the flexed position, all ETT moved caudally. The average distance moved was 3.5 vertebral spaces, with 81.8% of ETT located caudal to C7 and seven tubes in endobronchial positions. Endotracheal tube occlusion caused by kinking at the atlanto-occipital joint was seen in four dogs during flexion of the neck. Based on this study, ETT position should be monitored during cervical manipulation.

Evaluation of toenail blood samples for blood gas analysis in the dog.

Blood gas values were compared in blood collected from cut toenails and femoral arteries in 50 healthy crossbred dogs that were sedated and allowed to breathe room air spontaneously. Blood samples from cut toenails were collected by microcapillary technique with Natelson tubes. Femoral artery samples were collected by arterial puncture. Blood values for PO2, PCO2, pH, and HCO3 were compared. There was good correlation for pH, PCO2, and bicarbonate, but not for PO2. Microcapillary samples should be collected in 10 seconds or less for the most accurate results. A metal mixing "flea" was unnecessary. When properly handled, the Natelson tube technique provides an alternative method for collection of blood gas samples.