Total intravenous anesthesia with Ketofol in rabbits: a comparison of the effects of constant rate infusion of midazolam, fentanyl or dexmedetomidine.

BACKGROUND: When inhalant anesthetic equipment is not available or during upper airway surgery, intravenous infusion of one or more drugs are commonly used to induce and/or maintain general anesthesia. Total intravenous anesthesia (TIVA) does not require endotracheal intubation, which may be more difficult to achieve in rabbits. A range of different injectable drug combinations have been used as continuous infusion rate in animals. Recently, a combination of ketamine and propofol (ketofol) has been used for TIVA in both human patients and animals. The purpose of this prospective, blinded, randomized, crossover study was to evaluate anesthetic and cardiopulmonary effects of ketofol total intravenous anesthesia (TIVA) in combination with constant rate infusion (CRI) of midazolam, fentanyl or dexmedetomidine in eight New Zealand White rabbits. Following IV induction with ketofol and endotracheal intubation, anesthesia was maintained with ketofol infusion in combination with CRIs of midazolam (loading dose [LD]: 0.3 mg/kg; CRI: 0.3 mg/kg/hr; KPM), fentanyl (LD: 6 µg/kg; CRI: 6 µg/kg/hr; KPF) or dexmedetomidine (LD: 3 µg/kg; CRI: 3 µg/kg/hr; KPD). Rabbits in the control treatment (KPS) were administered the same volume of saline for LD and CRI. Ketofol infusion rate (initially 0.6 mg kg- 1 minute- 1 [0.3 mg kg- 1 minute- 1 of each drug]) was adjusted to suppress the pedal withdrawal reflex. Ketofol dose and physiologic variables were recorded every 5 min. RESULTS: Ketofol induction doses were 14.9 ± 1.8 (KPM), 15.0 ± 1.9 (KPF), 15.5 ± 2.4 (KPD) and 14.7 ± 3.4 (KPS) mg kg- 1 and did not differ among treatments (p > 0.05). Ketofol infusion rate decreased significantly in rabbits in treatments KPM and KPD as compared with saline. Ketofol maintenance dose in rabbits in treatments KPM (1.0 ± 0.1 mg/kg/min) and KPD (1.0 ± 0.1 mg/kg/min) was significantly lower as compared to KPS (1.3 ± 0.1 mg/kg/min) treatment (p < 0.05). Ketofol maintenance dose did not differ significantly between treatments KPF (1.1 ± 0.3 mg/kg/min) and KPS (1.3 ± 0.1 mg/kg/min). Cardiovascular variables remained at clinically acceptable values but ketofol infusion in combination with fentanyl CRI was associated with severe respiratory depression. CONCLUSIONS: At the studied doses, CRIs of midazolam and dexmedetomidine, but not fentanyl, produced ketofol-sparing effect in rabbits. Mechanical ventilation should be considered during ketofol anesthesia, particularly when fentanyl CRI is used.

Effect of direct therapeutic ultrasound exposure of ovaries on histopathology, inflammatory response, and oxidative stress in dogs.

BACKGROUND: This research was designed to evaluate the effects of therapeutic ultrasound waves on ovarian germinal tissue and inflammatory cytokines (interleukin-6 (IL-6), IL1ß, tumor necrosis factor-α (TNF-α)), acute phase proteins (serum amyloid A (SAA), C reactive protein (CRP)) and oxidative stress (total antioxidant capacity (TAC), and malondialdehyde (MDA)) in dogs. Twenty-six clinically healthy adult mix-breed female dogs were aligned into three groups. Laparotomy was performed in control (n = 6) and treatment (T5, n = 10; T10, n = 10) groups. The ultrasonic exposure of ovaries in treatment groups was performed during laparotomy by round motions of the therapeutic ultrasonic transducer on both ovaries (1 MHz frequency, 1.5 W/cm2) for 5 min in the T5 group and for 10 min in the T10 group. Blood samples were collected from the jugular vein into a plain glass tube on days 0 (before laparotomy), 3, 6, and 9 after surgery. All control and treatment groups' dogs were ovariectomized for histological evaluation on day 60 after laparotomy or laparotomy + ultrasound exposure. RESULTS: Direct exposure of ovaries with therapeutic ultrasound waves induced inflammation and oxidative stress comparison with the control group. Histopathological evaluation of treated ovaries with ultrasound waves indicated a decreased number of primordial follicles (ovarian reserve) and oocyte preservation scores compared with ovaries in the control group. CONCLUSIONS: These changes may cause subfertility in the long term. It seems that inflammatory response and oxidative stress are factors in the permanent damage of ovarian tissue.

Comparison of propofol infusion rate required to abolish swallowing or pedal withdrawal reflexes in dogs.

In a prospective, randomized, experimental non-blinded study, the continuous infusions rates of propofol required to prevent swallowing (P-SR) or pedal withdrawal reflex (P-WR) were evaluated in healthy premedicated dogs. Dogs were randomly assigned to one of two treatments at weekly intervals. Following premedication with a combination of acepromazine and methadone, anesthesia was induced with propofol (4.00 mg kg-1 per min) and was maintained for 90 min. The propofol infusion rate was increased or decreased by 0.05 mg kg-1 per min based on positive or negative swallowing (P-SR) or pedal withdrawal reflexes (P-WR). Propofol induction doses were 2.12 ± 0.43 mg kg-1 (P-SR) and 2.14 ± 0.31 mg kg-1 (P-WR), which were not significantly different. The mean (±SD) propofol infusion rate was significantly higher for P-WR (0.26 ± 0.10 mg kg-1 per min) when compared to P-SR (0.22 ± 0.12 mg kg-1 per min). During the last 30 min, the mean propofol infusion rates were 0.09 ± 0.02 and 0.18 ± 0.03 mg kg-1 per min for P-SR and P-WR, respectively. There were no significant differences between treatments with respect to heart rate (HR), respiratory rate, arterial blood pressure, end-tidal CO2 partial pressure, hemoglobin oxygen saturation, partial pressures of oxygen or pH. Transient apnea lasting up to three minutes was observed in three dogs with each treatment. Propofol infusion rate of 0.22 ± 0.12 mg kg-1 per min can be used in premedicated dogs requiring tracheal intubation and undergoing mechanical ventilation, non-painful procedures or painful procedures with local anesthetic techniques.

Ketamine-propofol for total intravenous anaesthesia in rabbits: a comparison of premedication with acepromazine-medetomidine, acepromazine-midazolam or acepromazine-morphine.

OBJECTIVE: To describe ketamine-propofol total intravenous anaesthesia (TIVA) following premedication with acepromazine and either medetomidine, midazolam or morphine in rabbits. STUDY DESIGN: Randomized, crossover experimental study. ANIMALS: A total of six healthy female New Zealand White rabbits (2.2 ± 0.3 kg). METHODS: Rabbits were anaesthetized on four occasions, each separated by 7 days: an intramuscular injection of saline alone (treatment Saline) or acepromazine (0.5 mg kg-1) in combination with medetomidine (0.1 mg kg-1), midazolam (1 mg kg-1) or morphine (1 mg kg-1), treatments AME, AMI or AMO, respectively, in random order. Anaesthesia was induced and maintained with a mixture containing ketamine (5 mg mL-1) and propofol (5 mg mL-1) (ketofol). Each trachea was intubated and the rabbit administered oxygen during spontaneous ventilation. Ketofol infusion rate was initially 0.4 mg kg-1 minute-1 (0.2 mg kg-1 minute-1 of each drug) and was adjusted to maintain adequate anaesthetic depth based on clinical assessment. Ketofol dose and physiological variables were recorded every 5 minutes. Quality of sedation, intubation and recovery times were recorded. RESULTS: Ketofol induction doses decreased significantly in treatments AME (7.9 ± 2.3) and AMI (8.9 ± 4.0) compared with treatment Saline (16.8 ± 3.2 mg kg-1) (p < 0.05). The total ketofol dose to maintain anaesthesia was significantly lower in treatments AME, AMI and AMO (0.6 ± 0.1, 0.6 ± 0.2 and 0.6 ± 0.1 mg kg-1 minute-1, respectively) than in treatment Saline (1.2 ± 0.2 mg kg-1 minute-1) (p < 0.05). Cardiovascular variables remained at clinically acceptable values, but all treatments caused some degree of hypoventilation. CONCLUSIONS AND CLINICAL RELEVANCE: Premedication with AME, AMI and AMO, at the doses studied, significantly decreased the maintenance dose of ketofol infusion in rabbits. Ketofol was determined to be a clinically acceptable combination for TIVA in premedicated rabbits.

Effects of epididymal sperm recovery methods on fresh and frozen-thawed sperm characteristics in dogs.

The cauda epididymis holds a collectible source of fertile spermatozoa in cases of obstructive azoospermia, sudden death, and after elective or emergency castration. The current study was conducted to compare three different epidydimal sperm collection methods (Percutaneous epididymal sperm aspiration (PESA), microsurgical epididymal sperm aspiration (MESA) and retrograde epididymal wash (EW)) in the dog. Fifteen large-breed adult dogs were applied for comparing the PESA (left testicles) with MESA (right testicles) techniques, while five dogs were used for evaluation of MESA (left testicles) versus EW (right testicles). The recovered sperm cells from MESA and EW were subjected to cryopreservation. Total sperm recovery, level of blood contamination and sperm quality markers (viability, morphology, plasma and acrosome membrane integrity, DNA fragmentation, and metabolic activity) were evaluated for fresh and frozen-thawed spermatozoa. We showed that the collection of epididymal sperm cells through the PESA method resulted in lower total sperm recovery and significantly reduced fresh sperm kinematic and quality measures. While, both MESA and EW procedures resulted in a high number of intact epididymal spermatozoa with appropriate cryo-tolerance potential. In conclusion, EW and MESA methods provide high-quality epidydimal spermatozoa with high cryopreservation potential in domestic dogs.

The analgesic interaction of tramadol and morphine in rats: An isobolographic study.

In order to assess possible synergistic antinociceptive interactions, the analgesic effects of intra-peritoneal tramadol and morphine administered either separately or in combination were determined using tail-flick latency test following exposure to radiant heat in rats. Groups of eight male Sprague-Dawley rats received either tramadol (3.90, 7.00, 12.50, and 22.20 mg kg-1) and morphine (1.26, 2.25, 4.00 and 7.10 mg kg-1) or a combination of tramadol and morphine (4 different combinations). The baseline latency was obtained before drug injection for each rat, then at 15, 30, 45, 60 and 75 min after injection. The effective dose (ED)50 for either tramadol or morphine individually was 11.70 mgkg-1 and 2.26 mg kg-1, respectively. Based on isobolographic analysis, the ED50 values obtained by drug combination were significantly less than the calculated additive values; which indicates that the co-administration of tramadol and morphine produces synergistic antinociception in the radiant heat tail-flick assay. Combination of morphine and tramadol administered intra-peritoneally can be used for the control of acute pain in rats.

Plasma concentrations of lidocaine following laryngeal administration or laryngeal and intratesticular administration in cats.

OBJECTIVE To determine plasma concentrations of lidocaine after laryngeal administration or laryngeal and intratesticular administration in cats. ANIMALS 14 healthy adult sexually intact male cats (7 cats/treatment). PROCEDURES Cats were randomly allocated to receive 0.1 mL of 2% or 10% lidocaine hydrochloride solution (treatments L2 and L10, respectively) sprayed on the larynx for laryngeal desensitization, followed by endotracheal intubation and isoflurane anesthesia. After a 7-day washout period, cats were again randomly allocated to receive treatment L2 or L10, and castration was performed under isoflurane anesthesia following intratesticular administration of 2% lidocaine solution (0.1 mL/kg). In both experiments, a blood sample for measurement of plasma lidocaine concentration was obtained before (0 minutes) and 3, 5, 10, 15, 20, 30, 45, 60, and 75 minutes after laryngeal administration of lidocaine solution. Anesthesia was discontinued at 60 minutes. Plasma lidocaine concentrations were measured with high-performance liquid chromatography. RESULTS After treatments L2 and L10, median maximum plasma lidocaine concentrations were 34.1 ng/mL (range, 0 to 279.4 ng/mL) and 93.6 ng/mL (range, 79.3 to 182.2 ng/mL), respectively. Time to maximum plasma concentration was 10 minutes (range, 0 to 20 minutes) for each treatment. When cats received intratesticular lidocaine administration following L2 or L10 treatment, median maximum plasma concentration was 181.0 ng/mL (range, 103.7 to 600.2 ng/mL) and 301.2 ng/mL (range, 265.8 to 1,770.0 ng/mL), respectively. CONCLUSIONS AND CLINICAL RELEVANCE On the basis of these data, combined laryngeal and intratesticular administration of lidocaine solution at a total dose of approximately 5 mg/kg appears to be safe for use in healthy adult cats.

Evaluation of the Sedative Effects of Diazepam, Midazolam, and Xylazine After Intranasal Administration in Juvenile Ostriches ( Struthio camelus ).

The sedative effects of diazepam, midazolam, and xylazine after intranasal administration were evaluated in 72 (36 male and 36 female) juvenile healthy ostriches ( Struthio camelus ), weighing 50-61 kg and aged 4-5 months. The birds were randomly divided into 3 groups (n = 24), then each group was further subdivided to 4 subgroups (n = 6). For each drug, 4 different doses were chosen and the total calculated dose was equally administered into either naris of the individual bird. The appropriate dose of each drug to produce standing chemical restraint or sternal recumbency was evaluated based on the onset time, the duration of maximum effect, and the duration of sedation. Midazolam showed significantly shorter onset time (2.9 ± 1.2 minutes) compared with xylazine (4.4 ± 1 minute) and diazepam (4.3 ± 0.4 minutes). Longer duration of sedation was also achieved with midazolam compared with xylazine and diazepam. Moderate sedation was achieved with diazepam (0.8 mg/kg), midazolam (0.4 mg/kg), and xylazine (2 mg/kg) for standing chemical restraint, with the maximum duration effects of 7.0 ± 1.4, 17.7 ± 4.1, and 9.2 ± 2.5 minutes, respectively. Deep sedation was also achieved with midazolam (0.8 mg/kg) and xylazine (4 mg/kg), with sternal recumbency duration of 21.7 ± 4.9 and 13.5 ± 2.6 minutes, respectively. The results of the present study show that intranasal administration can be an effective route for delivery of sedatives in juvenile ostriches. Intranasal midazolam and xylazine could be suggested for standing chemical restraint or inducing sternal recumbency in juvenile ostriches.

Comparison of lidocaine, lidocaine-morphine, lidocaine-tramadol or bupivacaine for neural blockade of the brachial plexus in fat-tailed lambs.

OBJECTIVE: To evaluate the onset time and duration of action of lidocaine, lidocaine-morphine, lidocaine-tramadol or bupivacaine for a neural blockade of the brachial plexus in fat-tailed lambs. STUDY DESIGN: Prospective, randomized, crossover, experimental study. ANIMALS: Seven healthy female fat-tailed Ghezel lambs weighing 27.0 ± 2.2 kg (mean ± SD). METHODS: Each lamb was administered four treatments for brachial plexus block (BPB): lidocaine 2% (5 mg kg(-1)) (LID), lidocaine 2% combined with morphine (0.1 mg kg(-1)) (LIDMO), lidocaine 2% combined with tramadol (1 mg kg(-1)) (LIDTR) or bupivacaine 0.5% (1.25 mg kg(-1)) (BUP), for a total treatment volume of 0.25 mL kg(-1). The brachial plexus was located with a peripheral nerve stimulator, and the treatment volume was injected in increments. Treatments were randomized and separated by at least 7 days. Onset and duration of a sensory block of the distal thoracic limb were evaluated using superficial and deep pin pricks and pinching of the skin with haemostatic forceps. RESULTS: The mean duration of sensory block was 100 ± 38 minutes in LID, 103 ± 35 minutes in LIDMO, 79 ± 28 minutes in LIDTR, and 335 ± 134 minutes in BUP. The mean duration of sensory and motor blocks in BUP were significantly longer compared with other treatments (p < 0.05). No clinical signs of local anaesthetic toxicity were noticed, and the rectal temperature did not differ significantly from baseline values in any treatments. CONCLUSIONS AND CLINICAL RELEVANCE: The addition of morphine or tramadol to lidocaine did not affect the duration of antinociception of lidocaine for brachial plexus block in fat-tailed lambs. Administration of bupivacaine provided a prolonged duration of action without obvious adverse effects.

Evaluation of the anti-nociceptive effects of morphine, tramadol, meloxicam and their combinations using the tail-flick test in rats.

The purpose of the present study was to evaluate anti-nociceptive effects of morphine, tramadol, meloxicam and their combinations in rats. Seventy male Wistar rats were divided into seven equal groups and randomly assigned to receive intraperitoneal saline (S) (control group, 1.0 mL kg(-1)), morphine (MO) (4.0 mg kg(-1)), tramadol (TR) (12.5 mg kg(-1)), meloxicam (ML) (1.0 mg kg(-1)), tramadol- morphine (TR-MO), meloxicam-morphine (ML-MO) and meloxicam-tramadol (ML-TR) at the same doses. Anti-nociception was evaluated using tail flick latency (TFL) test at 45, 60, 75, 90 and 120 min after drug injection. The TFL was significantly higher in TR and MO groups compared to S group for 90 and 120 min, respectively. No significant change in TFL from baseline values was observed at all time points in ML group. Among rats that received combination of analgesics, those that received TR-MO had significantly greater TFL. There was no significant difference in TFL between ML-TR and ML-MO groups. In conclusion, TR, MO and their combination all provided acceptable anti-nociceptive effects in rats. Meloxicam at the given dosage (1.0 mg kg(-1)) did not demonstrate any anti-nociceptive effect when evaluated by TFL test.

Caudal epidural anti-nociception using lidocaine, bupivacaine or their combination in cows undergoing reproductive procedures.

OBJECTIVE: To evaluate the anti-nociceptive effects of lidocaine, lidocaine-bupivacaine combination or bupivacaine following caudal epidural administration in cows undergoing reproductive procedures. STUDY DESIGN: Blinded, randomized experimental study. ANIMALS: Thirty seven healthy Holstein cows (mean weight ± SD, 633 ± 41 kg). METHODS: Animals were allocated randomly to receive one of four treatments: group LID, 0.2 mg kg(-1) lidocaine 2%; group LID-BUP, lidocaine-bupivacaine mixture in a 1:1 volume ratio (0.1 mg kg(-1) and 0.025 mg kg(-1), respectively); group BUP-LD, 0.05 mg kg(-1) bupivacaine 0.5%; and group BUP-HD, 0.06 mg kg(-1) bupivacaine 0.5%. The onset and duration of perineal anti-nociception were determined using superficial and deep pin pricks and the number of cows with complete perineal anti-nociception was recorded. Parameters were compared using anova followed by Duncan's test where relevant. RESULTS: Mean ± SD time to onset of anti-nociception following epidural administration of BUP-LD was significantly longer than for LID-BUP (p < 0.05). The duration (in minutes) of perineal anti-nociception was significantly longer following epidural administration of BUP-HD (247 ± 31) versus LID-BUP (181 ± 33) and LID (127 ± 25) minutes respectively. The % of cows with complete anti-nociception was increased in the group treated with BUP-HD compared to BUP-LD. Severe ataxia or recumbency did not occur in any groups. CONCLUSIONS AND CLINICAL RELEVANCE: Epidurally administered bupivacaine, at a dose of 0.06 mg kg(-1), may provide satisfactory caudal epidural anti-nociception for longer-duration obstetric and surgical procedures.

Brachial plexus block using lidocaine/epinephrine or lidocaine/xylazine in fat-tailed sheep.

This blinded, randomized experimental study was designed to evaluate the analgesic effects of adding epinephrine or xylazine to lidocaine solution for brachial plexus block (BPB) in sheep. Nine healthy, fat-tailed female lambs (26.6 ± 1.5 kg) were randomly allocated into three groups: lidocaine 2%, 5 mg kg(-1) (LID, n = 6), lidocaine (5 mg kg(-1)) with epinephrine 5 µg mL(-1) (LIDEP, n = 6) or lidocaine (5 mg kg(-1)) with xylazine 0.05 mg kg(-1) (LIDXY, n = 6). Each animal was tested twice. The sheep received a total volume of 0.25 mL kg(-1) for BPB. A nerve stimulator was used to locate the nerves of the brachial plexus. Onset and duration of analgesia of the forelimb were evaluated using superficial and deep pin prick and pinching of skin with a hemostat clamp. Heart and respiratory rates, and rectal temperature were recorded before and at predetermined intervals following the completion of the block. Brachial administration of LID, LIDEP or LIDXY produced forelimb analgesia within 11.3, 11.0 and 7.0 minutes, respectively. The mean duration of analgesia was 100.0 min in LID and 133.2 min in LIDEP group. The mean duration of analgesia in LIDXY group (186.8 min) was significantly longer compared with LID group. In LIDEP group a significant increase in heart rate occurred 5 min after drug administration. Heart rate decreased from 35 to 80 min in sheep received LIDXY. In conclusion, the addition of xylazine to lidocaine solution for BBP provided a prolonged duration of action without any adverse effects in fat-tailed sheep.

The effects of adding epinephrine or xylazine to lidocaine solution for lumbosacral epidural analgesia in fat-tailed sheep.

This blinded, randomised experimental study was designed to compare the analgesic effects of lumbosacral epidural administration of lidocaine-epinephrine or lidocaine-xylazine combinations in fat-tailed sheep. Nine healthy fat-tailed male lambs (mean ± s.d. age, 4.6 ± 0.4 months; weight, 24.6 kg ± 2.5 kg) were randomly allocated into four groups of six sheep: lidocaine 2% (LID), lidocaine-epinephrine 5 µg/mL (LIDEP), lidocaine-xylazine 0.05 mg/kg (LIDXY) or bupivacaine 0.5% (BUP). The onset and duration of flank, perineum and hindlimb anaesthesia and the onset and duration of hindlimb paralysis were recorded. Epidural administration of LID, LIDEP, LIDXY or BUP produced anaesthesia within 6.6 min, 7.6 min, 3.4 min and 8.4 min, respectively. The mean onset of anaesthesia in the LIDXY group was significantly shorter compared with the BUP group (p = 0.02). The mean duration of anaesthesia was 107.9 min, 190.4 min, 147.6 min and 169.7 min for LID, LIDEP, LIDXY and BUP, respectively. The onset of hindlimb paralysis was faster in the LIDXY group than in the BUP group; however, the duration of hindlimb paralysis was shorter in LIDXY compared with LIDEP. Epidural administration of LIDEP or LIDXY provides a comparable duration of local anaesthesia without any adverse effects in fat-tailed sheep. Epidural LIDXY did not appear to be advantageous over epidural LIDEP.

Comparison of lidocaine, lidocaine/epinephrine or bupivacaine for thoracolumbar paravertebral anaesthesia in fat-tailed sheep.

OBJECTIVE: To evaluate the speed of onset and duration of loss of sensation in the flank following paravertebral administration of lidocaine (with or without epinephrine) or bupivacaine. STUDY DESIGN: Blinded, randomized experimental study. ANIMALS: Nine healthy fat-tailed male lambs (mean weight ± SD, 22.9 ± 3 kg). Each animal was used twice. METHODS: Animals were allocated randomly to receive two of three treatments: lidocaine 2% (LID, n = 6), lidocaine with epinephrine 5 µg mL(-1) (LIDEP, n = 6) or bupivacaine 0.5% (BUP, n = 6). The sheep received a total volume of 9 mL (3 mL for each paravertebral nerve) of anaesthetic. Onset and duration of loss of sensation on the flank were evaluated using nociceptive stimuli (superficial and deep pin-prick and clamping with a haemostat). Values for heart (HR) and respiratory (f(R) ) rates, rectal and skin temperatures were recorded before and at predetermined intervals after paravertebral injection. Parameters were compared using anova followed by Duncan's test where relevant. RESULTS: Mean ± SD times to onset of loss of flank sensation following paravertebral administration of LID, LIDEP or BUP were 1.8 ± 1.2, 2.0 ± 0.9 and 3.6 ± 1.3 minutes, respectively. Durations of action in minutes were 65 ± 18, 95 ± 46 and 303 ± 98, respectively. Onset and duration of effects after BUP treatment were significantly longer than after LID or LIDEP (p < 0.05), but did not differ significantly between LID and LIDEP. No clinical signs of local anaesthetic toxicity were noticed and HR and f(R) remained stable with all protocols. CONCLUSIONS AND CLINICAL RELEVANCE: Paravertebral administration of bupivacaine produces a longer duration of anaesthesia when compared to lidocaine with or without epinephrine and is indicated when prolonged flank surgery is to be performed.

Evaluation of the isoflurane-sparing effects of lidocaine infusion during umbilical surgery in calves.

OBJECTIVE: To evaluate the isoflurane-sparing effects of lidocaine administered by constant rate infusion (CRI) during umbilical surgery in calves. STUDY DESIGN: Randomized 'blinded' prospective clinical study. ANIMALS: Thirty calves (mean 4.7 ± SD 2.5 weeks old) undergoing umbilical surgery. METHODS: After premedication with xylazine (0.1 mg kg(-1) , IM), anaesthesia was induced with ketamine (4 mg kg(-1) , IV) and maintained with isoflurane in O(2) administered through a circle breathing system. The calves were assigned randomly to receive a bolus of 2 mg kg(-1) lidocaine IV after induction of anaesthesia, followed by CRI of 50 µg kg(-1) minute(-1) (group L, n=15) or a bolus and CRI of 0.9% sodium chloride (NaCl, group S, n=15). End-tidal isoflurane was adjusted to achieve adequate depth of anaesthesia. Heart rate, direct arterial blood pressure and body temperature were measured intraoperatively. Groups were compared by t- tests, anova or Mann-Whitney rank sum test as appropriate. RESULTS: The end-tidal concentration of isoflurane (median, IQR) was significantly lower in group L [1.0% (0.94-1.1)] compared to group S [1.2% (1.1-1.5)], indicating a 16.7% reduction in anaesthetic requirement during lidocaine CRI. Cardiopulmonary parameters and recovery times did not differ significantly between groups. CONCLUSION AND CLINICAL RELEVANCE: Lidocaine CRI may be used as a supplement to inhalation anaesthesia during umbilical surgery in calves in countries where such a protocol would be within the legal requirements for veterinary use in food animals. This study did not show any measurable benefit to the calves other than a reduction in isoflurane requirement.

Clinical evaluation of intranasal benzodiazepines, alpha-agonists and their antagonists in canaries.

OBJECTIVE: To evaluate the effects of intranasal benzodiazepines (midazolam and diazepam), alpha(2)-agonists (xylazine and detomidine) and their antagonists (flumazenil and yohimbine) in canaries. STUDY DESIGN: Prospective randomized study. ANIMALS: Twenty-six healthy adult domesticated canaries of both sexes, weighing 18.3 +/- 1.0 g. METHODS: In Study 1 an attempt was made to determine the dose of each drug that allowed treated canaries to be laid in dorsal recumbency for at least 5 minutes, i.e. its effective dose. This involved the evaluation of various doses, during which equal volumes of the tested drug were administered slowly into each nostril. In study 2 the onset of action, duration and quality of sedation induced by each drug at its effective dose were evaluated. The efficacy of flumazenil and yohimbine in antagonizing the effects of the sedative drugs was also studied. RESULTS: In study 1 administration of 25 microL per nostril diazepam (5 mg mL(-1) solution) or midazolam (5 mg mL(-1) solution) to each bird caused adequate sedation within 1-2 minutes; birds did not move when placed in dorsal recumbency. After administration of 12 microL per nostril of either xylazine (20 mg mL(-1)) or detomidine (10 mg mL(-1)), birds seemed heavily sedated and assumed sternal recumbency but could not be placed in dorsal recumbency. Higher doses of xylazine (0.5 mg per nostril) or detomidine (0.25 mg per nostril) prolonged sedation but did not produce dorsal recumbency. In study 2 in all treatment groups, onset of action was rapid. Duration of dorsal recumbency was significantly longer (p < 0.05) with diazepam (38.4 +/- 10.5 minutes) than midazolam (17.1 +/- 2.2 minutes). Intranasal flumazenil (2.5 microg per nostril) significantly reduced recumbency time. Duration of sedation was longer with alpha(2)-agonists compared with benzodiazepines. Detomidine had the longest duration of effect (257.5 +/- 1.5 minutes) and midazolam the shortest (36.9 +/- 2.4 minutes). Nasally administered flumazenil significantly reduced the duration of sedation with diazepam and midazolam while yohimbine (120 microg per nostril) effectively antagonized the effects of xylazine and detomidine. CONCLUSION: Intranasal benzodiazepines produce rapid and effective sedation in canaries. Intranasal alpha(2) agonists produce sedation but not sustained recumbency. Specific antagonists are also effective when used by this route. Clinical relevance Intranasal sedative drug administration is an acceptable alternative method of drug delivery in canaries.

Sedative effects of midazolam and xylazine with or without ketamine and detomidine alone following intranasal administration in Ring-necked Parakeets.

OBJECTIVE: To evaluate the effects of intranasal administration of midazolam and xylazine (with or without ketamine) and detomidine and their specific antagonists in parakeets. DESIGN: Prospective study. ANIMALS: 17 healthy adult Ring-necked Parakeets (Psittacula krameri) of both sexes (mean weight, 128.83+/-10.46 g [0.28+/-0.02 lb]). PROCEDURE: The dose of each drug or ketamine-drug combination administered intranasally that resulted in adequate sedation (ie, unrestrained dorsal recumbency maintained for >or=5 minutes) was determined; the onset of action, duration of dorsal recumbency, and duration of sedation associated with these treatments were evaluated. The efficacy of the reversal agents flumazenil, yohimbine, and atipamezole was also evaluated. RESULTS: In parakeets, intranasal administration of midazolam (7.3 mg/kg [3.32 mg/lb]) or detomidine (12 mg/kg [5.45 mg/lb]) caused adequate sedation within 2.7 and 3.5 minutes, respectively. Combinations of midazolam (3.65 mg/kg [1.66 mg/lb]) and xylazine (10 mg/kg [4.55 mg/lb]) with ketamine (40 to 50 mg/kg [18.2 to 22.7 mg/lb]) also achieved adequate sedation. Compared with detomidine, duration of dorsal recumbency was significantly longer with midazolam. Intranasal administration of flumazenil (0.13 mg/kg [0.06 mg/lb]) significantly decreased midazolam-associated recumbency time. Compared with the xylazineketamine combination, duration of dorsal recumbency was longer after midazolam-ketamine administration. Intranasal administration of flumazenil, yohimbine, or atipamezole significantly decreased the duration of sedation induced by midazolam, xylazine, or detomidine, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Intranasal administration of sedative drugs appears to be an acceptable method of drug delivery in Ring-necked Parakeets. Reversal agents are also effective when administered via this route.