Search Results

Abstract

Objective—To compare anesthetic, analgesic, and cardiorespiratory effects in dogs after IM administration of dexmedetomidine (7.5 μg/kg)–butorphanol (0.15 mg/kg)–tiletamine-zolazepam (3.0 mg/kg; DBTZ) or dexmedetomidine (15.0 μg/kg)-tramadol (3.0 mg/kg)-ketamine (3.0 mg/kg; DTrK) combinations.

Animals—6 healthy adult mixed-breed dogs.

Procedures—Each dog received DBTZ and DTrK in a randomized, crossover-design study with a 5-day interval between treatments. Cardiorespiratory variables and duration and quality of sedation-anesthesia (assessed via auditory stimulation and sedation-anesthesia scoring) and analgesia (assessed via algometry and electrical nerve stimulation) were evaluated at predetermined intervals.

Results—DBTZ or DTrK induced general anesthesia sufficient for endotracheal intubation ≤ 7 minutes after injection. Anesthetic quality and time from drug administration to standing recovery (131.5 vs 109.5 minutes after injection of DBTZ and DTrK, respectively) were similar between treatments. Duration of analgesia was significantly longer with DBTZ treatment, compared with DTrK treatment. Analgesic effects were significantly greater with DBTZ treatment than with DTrK treatment at several time points. Transient hypertension (mean arterial blood pressure > 135 mm Hg), bradycardia (heart rate < 60 beats/min), and hypoxemia (oxygen saturation < 90% via pulse oximetry) were detected during both treatments. Tidal volume decreased significantly from baseline with both treatments and was significantly lower after DBTZ administration, compared with DTrK, at several time points.

Conclusions and Clinical Relevance—DBTZ or DTrK rapidly induced short-term anesthesia and analgesia in healthy dogs. Further research is needed to assess efficacy of these drug combinations for surgical anesthesia. Supplemental 100% oxygen should be provided when DBTZ or DTrK are used.

Abstract

Abstract

Objective—To determine in vitro output temperature differences of 3 IV fluid warmers.

Design—Prospective, randomized study.

Sample—3 IV fluid warmers.

Procedures—Warming capabilities of a distance-dependent blood and fluid warmer marketed for human and veterinary use (product A) and a veterinary-specific distance-dependent fluid warmer (product B) were compared at 0, 4, 8, and 12 cm from the device to the test vein and at flow rates of 20, 60, 100, 140, 180, 220, 260, and 300 mL/h with room temperature (approx 22°C) fluids (phase 1). The superior warming device was compared against a distance-independent IV fluid warmer (product C) with room temperature fluids at the same flow rates (phase 2). The effect of prewarmed fluids (38°C) versus room temperature fluids was evaluated with the superior warming device from phase 2 (phase 3).

Results—In phase 1, product B produced significantly warmer fluids than product A for all flow rates and distances. Both distance-dependent devices produced warmer fluid at 0 cm, compared with 4, 8, and 12 cm. In phase 2, product B produced warmer fluid than product C at 60, 100, 140, and 180 mL/h. In phase 3, there was no significant benefit to use of prewarmed fluids versus room temperature fluids. Output temperatures ≥ 36.4°C were achieved for all rates ≥ 60 mL/h.

Conclusions and Clinical Relevance—Product B had superior warming capabilities. Placing the fluid warmer close to the patient is recommended. Use of prewarmed fluids had no benefit. Lower IV fluid flow rates resulted in lower output fluid temperatures.

Abstract

Objective—To determine whether heavy (≥ 680 kg [≥ 1,500 lb]) draft horses undergoing surgical treatment for acute signs of abdominal pain were at a greater risk for anesthetic and postoperative complications and lower postoperative survival rates than light (< 680 kg) draft horses.

Design—Retrospective case series.

Animals—72 draft horses.

Procedures—Medical records of draft horses that underwent exploratory celiotomy for signs of acute abdominal pain from October 1983 to December 2002 were reviewed. Medical records of draft horses in which a celiotomy was performed for correction of reproductive abnormalities were not included in the study.

Results—When compared with light draft horses, heavy draft horses had longer durations of anesthesia, more postoperative complications, and lower survival rates. Seventy-six percent of horses that recovered from anesthesia had postoperative complications. Postoperative complications associated with low survival rates included myopathy and neuropathy, ileus, diarrhea, and endotoxemia. All horses with postoperative myopathy and neuropathy died or were euthanized. The short-term survival rate for horses that recovered from anesthesia was 60%. Horses undergoing small intestinal surgery had a worse prognosis for short-term survival than those undergoing large intestinal surgery. The survival rate for horses for which long-term (> 1 year) follow-up information was available was 50%.

Conclusions and Clinical Relevance—Draft horses weighing > 680 kg that underwent surgery because of acute signs of abdominal pain had longer durations of anesthesia, more postoperative complications, and higher mortality rates than draft horses weighing < 680 kg.

Abstract

Objective—To compare efficacy and cardiorespiratory effects of dexmedetomidine and ketamine in combination with butorphanol, hydromorphone, or buprenorphine (with or without reversal by atipamezole) in dogs undergoing castration.

Design—Prospective, randomized, split-plot, blinded study.

Animals—30 healthy client-owned sexually intact male dogs.

Procedures—Dogs (n = 10 dogs/group) were assigned to receive dexmedetomidine (15 μg/kg [6.82 μg/lb]) and ketamine (3 mg/kg [1.36 mg/lb]) with butorphanol (0.2 mg/kg [0.09 mg/lb]; DKBut), the same dosages of dexmedetomidine and ketamine with hydromorphone (0.05 mg/kg [0.023 mg/lb]; DKH), or the same dosages of dexmedetomidine and ketamine with buprenorphine (40 μg/kg [18.18 μg/lb]; DKBup). All drugs were administered as a single IM injection for induction and maintenance of anesthesia for castration. At conclusion of the surgery, 5 dogs in each treatment group received atipamezole (150 μg/kg [68.18 μg/lb], IM), and the remainder received saline (0.9% NaCl) solution IM. Cardiorespiratory variables and quality of anesthesia were assessed. Supplemental isoflurane was administered to the dogs when anesthesia was considered inadequate during surgery.

Results—All drug combinations rapidly induced anesthesia. Dogs were intubated within 10 minutes after injection. Supplemental isoflurane was needed during surgery in 1, 3, and 4 dogs in the DKBup, DKBut, and DKH groups, respectively. Dogs that received atipamezole had a significantly shorter recovery time. Some dogs in each group had bradycardia and hypoxemia with hypertension.

Conclusions and Clinical Relevance—DKBup was the most suitable injectable anesthetic combination used. Recovery was shortened by IM administration of atipamezole. There were minimal adverse effects in all groups.

Abstract

Objective—To investigate hemodynamic effects of acepromazine and dexmedetomidine premedication in dogs undergoing general anesthesia induced with propofol and maintained with isoflurane in oxygen and assess the influence of these drugs on oxygen-carrying capacity and PCV.

Design—Prospective, randomized crossover study.

Animals—6 healthy adult dogs.

Procedures—Dogs received acepromazine (0.05 mg/kg [0.023 mg/lb]) or dexmedetomidine (15.0 μg/kg [6.82 μg/lb]) IM. Fifteen minutes later, anesthesia was induced with propofol and maintained at end-tidal isoflurane concentration of 1.28% (1 minimum alveolar concentration) for 30 minutes. Hemodynamic variables were recorded at predetermined times. The experiment was repeated 48 hours later with the alternate premedication. Results were analyzed by repeated-measures ANOVA with a mixed-models procedure.

Results—Bradycardia, hypertension, and significant cardiac output (CO) reduction developed after dexmedetomidine premedication but improved during isoflurane anesthesia. Hypotension developed after acepromazine administration and persisted throughout the isoflurane maintenance period, but CO was maintained throughout the anesthetic period when dogs received this treatment. Oxygen delivery and consumption were not different between treatments at most time points, whereas arterial oxygen content was lower with acepromazine premedication owing to lower PCV during isoflurane anesthesia.

Conclusions and Clinical Relevance—Acepromazine exacerbated hypotension, but CO did not change in dogs anesthetized with propofol and isoflurane. Dexmedetomidine reduced CO but prevented propofol-isoflurane–induced hypotension. In general, oxygen-carrying capacity and PCV were higher in dexmedetomidine-treated than in acepromazine-treated dogs anesthetized with propofol and isoflurane.

Abstract

Objective—To evaluate hemodynamic effects in dogs after IM administration of dexmedetomidine (7.5 μg/kg, butorphanol (0.15 mg/kg), and tiletamine-zolazepam (3 mg/kg [DBTZ]) or dexmedetomidine (15 μg/kg), butorphanol (0.3 mg/kg), and ketamine (3 mg/kg [DBK]).

Animals—5 healthy adult mixed-breed dogs.

Procedures—Each dog received DBTZ and DBK in a randomized crossover study with a 48-hour interval between treatments. Anesthesia was induced and maintained with sevoflurane in 100% oxygen while instrumentation with Swan-Ganz and arterial catheters was performed. Following instrumentation, hemodynamic measurements were recorded at 3.54% (1.5 times the minimum alveolar concentration) sevoflurane; then sevoflurane administration was discontinued, and dogs were allowed to recover. Six hours after cessation of sevoflurane administration, baseline hemodynamic measurements were recorded, each dog was given an IM injection of DBTZ or DBK, and hemodynamic measurements were obtained at predetermined intervals for 70 minutes.

Results—DBTZ and DBK induced hypoventilation (Paco ₂, approx 60 to 70 mm Hg), respiratory acidosis (pH, approx 7.2), hypertension (mean arterial blood pressure, approx 115 to 174 mm Hg), increases in systemic vascular resistance, and reflex bradycardia. Cardiac output, oxygen delivery, and oxygen consumption following DBTZ or DBK administration were similar to those following sevoflurane administration to achieve a surgical plane of anesthesia. Blood l-lactate concentrations remained within the reference range at all times for all protocols.

Conclusions and Clinical Relevance—In healthy dogs, both DBTZ and DBK maintained oxygen delivery and oxygen consumption to tissues and blood lactate concentrations within the reference range. However, ventilation should be carefully monitored and assisted when necessary to prevent hypoventilation.

Abstract

Objective—To determine the cardiovascular and respiratory effects of water immersion in horses recovering from general anesthesia.

Animals—6 healthy adult horses.

Procedure—Horses were anesthetized 3 times with halothane and recovered from anesthesia while positioned in lateral or sternal recumbency in a padded recovery stall or while immersed in a hydropool. Cardiovascular and pulmonary functions were monitored before and during anesthesia and during recovery until horses were standing. Measurements and calculated variables included carotid and pulmonary arterial blood pressures (ABP and PAP, respectively), cardiac output, heart and respiratory rates, arterial and mixed venous blood gases, minute ventilation, end expiratory transpulmonary pressure (P_endXes), maximal change in transpulmonary pressure (ΔP_tpmax), total pulmonary resistance (R_L), dynamic compliance (C_dyn), and work of breathing ().

Results—Immersion in water during recovery from general anesthesia resulted in values of ABP, PAP, P_endXes, ΔP_tpmax, R_L, and that were significantly greater and values of C_dyn that were significantly less, compared with values obtained during recovery in a padded stall. Mode of recovery had no significant effect on any other measured or calculated variable.

Conclusions and Clinical Relevance—Differences in pulmonary and cardiovascular function between horses during recovery from anesthesia while immersed in water and in a padded recovery stall were attributed to the increased effort needed to overcome the extrathoracic hydrostatic effects of immersion. The combined effect of increased extrathoracic pressure and PAP may contribute to an increased incidence of pulmonary edema in horses during anesthetic recovery in a hydropool. (Am J Vet Res 2001;62:1903–1910)

Abstract

Objective—To compare the effect of oral administration of tramadol alone and with IV administration of butorphanol or hydromorphone on the minimum alveolar concentration (MAC) of sevoflurane in cats.

Design—Crossover study.

Animals—8 healthy 3-year-old cats.

Procedures—Cats were anesthetized with sevoflurane in 100% oxygen. A standard tail clamp method was used to determine the MAC of sevoflurane following administration of tramadol (8.6 to 11.6 mg/kg [3.6 to 5.3 mg/lb], PO, 5 minutes before induction of anesthesia), butorphanol (0.4 mg/kg [0.18 mg/lb], IV, 30 minutes after induction), hydromorphone (0.1 mg/kg [0.04 mg/lb], IV, 30 minutes after induction), saline (0.9% NaCl) solution (0.05 mL/kg [0.023 mL/lb], IV, 30 minutes after induction), or tramadol with butorphanol or with hydromorphone (same doses and routes of administration). Naloxone (0.02 mg/kg [0.009 mg/lb], IV) was used to reverse the effects of treatments, and MACs were redetermined.

Results—Mean ± SEM MACs for sevoflurane after administration of tramadol (1.48 ± 0.20%), butorphanol (1.20 ± 0.16%), hydromorphone (1.76 ± 0.15%), tramadol and butorphanol (1.48 ± 0.20%), and tramadol and hydromorphone (1.85 ± 0.20%) were significantly less than those after administration of saline solution (2.45 ± 0.22%). Naloxone reversed the reductions in MACs.

Conclusions and Clinical Relevance—Administration of tramadol, butorphanol, or hydromorphone reduced the MAC of sevoflurane in cats, compared with that in cats treated with saline solution. The reductions detected were likely mediated by effects of the drugs on opioid receptors. An additional reduction in MAC was not detected when tramadol was administered with butorphanol or hydromorphone.

Abstract

Objective—To compare the efficacy of preoperative administration of buprenorphine (via oral transmucosal [OTM] and IV routes) for postoperative analgesia in dogs undergoing ovariohysterectomy.

Design—Prospective, randomized, blinded study.

Animals—18 dogs undergoing routine ovariohysterectomy.

Procedures—Dogs were allocated to 3 groups (6 dogs/group) and were assigned to receive buprenorphine (20 μg/kg [9.09 μg/lb], IV; a low dose [20 μg/kg] via OTM administration [LOTM]; or a high dose [120 μg/kg [54.54 μg/lb] via OTM administration [HOTM]) immediately before anesthetic induction with propofol and maintenance with isoflurane for ovariohysterectomy. Postoperative pain was assessed by use of a dynamic interactive pain scale. Dogs were provided rescue analgesia when postoperative pain exceeded a predetermined threshold. Blood samples were collected, and liquid chromatography-electrospray ionization-tandem mass spectrometry was used to determine plasma concentrations of buprenorphine and its metabolites. Data were analyzed with an ANOVA.

Results—Body weight, surgical duration, propofol dose, isoflurane concentration, and cardiorespiratory variables did not differ significantly among treatment groups. Number of dogs requiring rescue analgesia did not differ significantly for the HOTM (1/6), IV (3/6), and LOTM (5/6) treatments. Similarly, mean ± SEM duration of analgesia did not differ significantly for the HOTM (20.3 ± 3.7 hours), IV (16.0 ± 3.8 hours), and LOTM (7.3 ± 3.3 hours) treatments. Plasma buprenorphine concentration was ≤ 0.60 ng/mL in 7 of 9 dogs requiring rescue analgesia.

Conclusions and Clinical Relevance—Buprenorphine (HOTM) given immediately before anesthetic induction can be an alternative for postoperative pain management in dogs undergoing ovariohysterectomy.