Atracurium infusion in the dog

The non-depolarizing muscle relaxant atracurium was administered to 25 dogs undergoing a variety of surgical procedures under general anaesthesia. An initial dose of 0–5 mg/kg was administered and when the block began to wear off an infusion was begun. A dose of 0–5 mg/kg/hr was administered by a simple infusion technique. Reversal of the neuromuscular block was carried out with either neostigmine or edrophonium preceded by atropine.     

Vecuronium infusion in the dog

The non-depolarising muscle relaxant vecuronium bromide was administered to 20 dogs undergoing a variety of surgical procedures under general anaesthesia. An initial dose of 0–1 mg/kg was administered and followed by an infusion of 0–1 mg/kg/hour. Reversal of the neuromuscular block was carried out with neostigmine and atropine.     

The clinical use of the neuromuscular blocking agent rocuronium in dogs

Objective The aim of this study was to characterize the onset and duration of action of the aminosteroid muscle relaxant rocuronium in dogs under clinical conditions. Study design Prospective single dose trial. Animals Twenty‐three dogs aged between 6 months and 12 years, weighing between 5.5 and 61.5 kg admitted to the University of Liverpool Small Animal Hospital between January and March 2000, and undergoing elective surgical procedures under general anaesthesia. Materials and methods Following induction of general anaesthesia, neuromuscular function was evaluated using train‐of‐four (TOF) stimulation. An initial dose of 0.4 mg kg^?1 rocuronium was administered intravenously (IV) and neuromuscular blockade was monitored by visually assessing the number of responses (twitches) to TOF stimulation (train‐of‐four count: TOFC). Incremental doses of 0.16 mg kg^?1 rocuronium were administered as indicated, when at least two twitches of the TOFC had returned. Results Rocuronium (0.4 mg kg^?1) abolished all responses to TOF stimulation in all dogs. The mean time to onset of neuromuscular blockade (complete abolition of all twitches) was 98 ± 52 seconds. Neuromuscular blockade (absence of all twitches to return of all four) lasted 32.3 ± 8.2 minutes. Incremental doses of 0.16 mg kg^?1 had a mean duration of action of 20.8 ± 4.9 minutes and up to seven increments were shown to be noncumulative. The effects of rocuronium were readily antagonized with neostigmine and atropine. Small transient increases in arterial blood pressure, which occurred in three dogs after the administration of rocuronium, were the only cardiovascular side‐effects observed. Conclusions Rocuronium is an effective nondepolarizing neuromuscular blocking agent in the dog, with a rapid onset of neuromuscular block after intravenous administration and an intermediate duration of action. Clinical relevance Rocuronium produced a neuromuscular block with similar characteristics to those obtained with vecuronium, thus apparently offering little advantage over vecuronium. However, its availability in aqueous solution and a longer shelf‐life increases convenience.     

Clinical observations on the use of the muscle relaxant rocuronium bromide in the dog

This study was designed to evaluate the effectiveness of neuromuscular blockade with rocuronium bromide (rocuronium) in eighty dogs anaesthetised for a variety of surgical procedures. Rocuronium 0.3 or 0.6 mg/kg (G03 and G06) was administered intravenously (IV) and neuromuscular function was monitored with an acceleromyograph. Lag time (LT) was >1 min in both groups. Onset time (OT) was 2+/-0.9 and 1.1+/-0.6 min in the groups given 0.3 and 0.6 mg/kg, respectively. There was a significantly longer time of action with 0.6 mg/kg in contrast to 0.3 mg/kg rocuronium. Time of no response (TonR) was 9.1+/-4.9-16.9+/-6.1 min in the groups given 0.3 and 0.6 mg/kg, respectively. The time from the end of injection until 25% recovery of the first twitch from the baseline value (T1(25)) was 13.8+/-5.5 and 22.3+/-6.7 min in the groups given 0.3 and 0.6 mg/kg, respectively. T1(25-75) was similar in both groups. Total recovery to baseline values was achieved in 23.8+/-6.6 and 31.9+/-6.5 min in the groups given 0.3 and 0.6 mg/kg, respectively (P<0.05). Premedication, maintenance agent, body position and stimulation site had no significant influence on the pharmacodynamic parameters in both groups. It was concluded that rocuronium is an effective non-depolarising muscle relaxant in the dog under clinical conditions.     

Evaluation of neostigmine antagonism at different levels of vecuronium-induced neuromuscular blockade in isoflurane anesthetized dogs

Residual neuromuscular block (NMB) during recovery from general anesthesia may be minimized by antagonizing NMB with neostigmine. We examined neostigmine for restoring neuromuscular function when administered at 2 levels of vecuronium-induced NMB in dogs. Eight healthy adult dogs received vecuronium 0.1 mg/kg body weight (BW), IV, during isoflurane anesthesia. Recovery from vecuronium occurred spontaneously (control group; C), or was enhanced with neostigmine, 0.04 mg/kg BW, IV, administered when 2 (N2) or 4 (N4) responses to train-of-four (TOF) stimulation were first observed. Duration of NMB was significantly shorter for N2 and N4 than for C. The period of complete NMB was equal for all groups; differences were observed during the recovery phase of NMB. Time of neostigmine-enhanced recovery was significantly shorter for N4 than N2, but overall duration of NMB was not reduced. Recovery from NMB was faster with neostigmine. There is no clinical advantage in delaying neostigmine administration once 2 responses to TOF are present.     

Neuromuscular blocking action of vecuronium in the dog and its reversal by neostigmine

Vecuronium bromide is one of a new series of competitive or nondepolarising muscle relaxants which is closely related chemically to pancuronium. Doses of 0.06, 0.1 and 0.2 mg kg-1 produced neuromuscular block in the anaesthetised dog. There were no observable effects on arterial blood pressure. The neuromuscular block was readily reversible with neostigmine preceded by atropine.     

Neuromuscular blocking properties of atracurium during sevoflurane or propofol anaesthesia in dogs

OBJECTIVE: To quantify the neuromuscular blockade (NMB) produced by atracurium in either sevoflurane or propofol-anaesthetized dogs. ANIMALS: Twelve healthy, female adult mixed-breed dogs weighing 13 +/- 3 kg (range 10-22 kg). MATERIALS AND METHODS: Three doses of atracurium (0.1, 0.2 and 0.3 mg kg(-1)) were tested at 1-week intervals. Anaesthesia was induced with inhaled sevoflurane or intravenous propofol and maintained with end-tidal sevoflurane concentrations of 1.95% (1.25 x MAC) or propofol 0.6 mg kg(-1) minute(-1) respectively. Acceleromyography and train-of-four stimulation of the fibular nerve were used for the assessment of NMB. The percentage depression of the first twitch (T1) and the fourth to the first twitch ratio (T4/T1), the maximum degree of neuromuscular block achieved and surgical muscle relaxation were recorded. Before and during neuro muscular blockade (at 10 minute intervals) body temperature, ECG, arterial blood pressure, inspired and expired CO2 concentrations and SpO2 were recorded. RESULTS: Atracurium produced a dose-dependent duration of NMB in both propofol and sevoflurane-anaesthetized dogs. Duration of block was longer in dogs anaesthetized with sevoflurane. All studied doses of atracurium caused twitch depression > or =95% with little or no cardiovascular changes. CONCLUSIONS: Sevoflurane produces a clinically relevant potentiation of atracurium-induced NMB in dogs compared with propofol. CLINICAL RELEVANCE: Significant differences in the potentiation of NMB drugs are encountered with commonly used anaesthetics in the dog.     

Influence of induced hypermagnesemia and hypocalcemia on neuromuscular blocking property of oxytetracycline in the horse.

The neurally evoked contractile response of the upper lip muscles of horses anesthetized with halothane was used to evaluate the neuromuscular blocking property of oxytetracycline which was administered intravenously at total dose rate of 21 to 28 mg/kg. This dose rate did not alter the contractile response which had a mean control value (and standard error; SE) of 1.76 plus or minus 0.22 kg. Arterial blood pressure was not affected by these dose rates. Neuromuscular blocking effect of the antibiotic occurred when it was administered during partial neuromuscular blockade which had been induced by infusion of magnesium sulfate (0.12 or 0.16 g/kg). Moderate hypocalcemia induced by infusion of sodium oxalate did not enhance the neuromuscular blocking property of this antibiotic. Since the dose rates of the oxytetracycline preparation used had a small effect on calcium concentration of equine serum (smaller than 0.3 mg/dl), calcium binding does not seem to play a major role in the neuromuscular blocking effect of this antibiotic. It was concluded that the weak neuromuscular blocking effect of oxytetracycline is not a significant etiologic factor in the acute type of adverse reaction to this antibiotic that is occasionally encountered in horses.     

Interactions between vecuronium and suxamethonium in the dog

The non-depolarising muscle relaxant vecuronium (0.2 mg kg-1) was administered to four dogs. At 50 per cent return of neuromuscular activity, as measured by the train-of-four technique, the depolarising muscle relaxant suxamethonium (0.3 mg kg-1) was injected intravenously. At 50 per cent return of neuromuscular activity reversal of the block was achieved with atropine and neostigmine. The duration of action of suxamethonium was reduced by the prior administration of vecuronium. In the second series of experiments the order of administration of the suxamethonium and vecuronium was reversed. Suxamethonium (0.3 mg kg-1) was administered first and at 50 per cent recovery vecuronium (0.2 mg kg-1) was given. At 50 per cent recovery of the twitch response after vecuronium administration the block was reversed with atropine and neostigmine. The previous administration of suxamethonium prolonged the duration of the vecuronium induced neuromuscular block.     

Observations on the neuromuscular blocking action of pipecuronium in the dog

Pipecuronium bromide is a nondepolarising muscle relaxant which is an analogue of pancuronium. Doses of 0.025 and 0.05 mg kg-1 produced neuromuscular block in the anaesthetised dog. Previous work would suggest that the drug has minimal effects on the cardiovascular system. However, a dose of 0.05 mg kg-1 produced a profound hypotension in one dog on one occasion. The neuromuscular blocking action of the drug would appear to be extremely variable as indicated by the wide range of the results. The neuromuscular block was readily reversible with neostigmine preceded by atropine.     

Use of rocuronium for endotracheal intubation of North American Gulf Coast box turtles

OBJECTIVE: To determine whether rocuronium, a reversible neuromuscular blocking agent, would provide safe, short-term immobilization to facilitate endotracheal intubation in turtles. DESIGN: Prospective study. ANIMALS: 30 healthy adult Gulf Coast box turtles. PROCEDURE: Turtles were given rocuronium, and responses were recorded every 3 minutes. Times to onset of effects, intubation, and recovery were recorded and analyzed for associations with dose and patient characteristics to determine an optimal dose range. Neostigmine and glycopyrrolate were given to augment recovery from neuromuscular blockade. RESULTS: Rocuronium administered at a dose of 0.25 to 0.5 mg/kg (0.11 to 0.23 mg/lb), IM, permitted intubation; lower doses were not effective. Mean +/- SD time to loss of the palpebral reflex was 6.4 +/- 4.0 minutes, and mean time to intubation was 9.2 +/- 6.4 minutes. Mean time to return of the palpebral reflex was 44 +/- 13.2 minutes, and mean time to walking was 55 +/- 16.6 minutes. Time to onset of effects was not associated with dose, but recovery times were prolonged with higher doses of rocuronium. Cardiac arrhythmias were observed in 13 (43%) turtles. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of rocuronium at a dose of 0.25 to 0.5 mg/kg is a safe and effective adjunct to general anesthesia in Gulf Coast box turtles. Because rocuronium does not provide any analgesic or sedative effects, the duration of neuromuscular blockade without anesthesia should be minimized to avoid undue distress.     

Neuromuscular block monitoring after the administration of 1 mg/kg intravenous cis‐atracurium in the anaesthetized pig

Neuromuscular blocking agents should be included as part of a balanced anaesthetic protocol to improve anaesthetic management, although doses are not always established for each species. Cis‐atracurium is a benzylisoquinolinium neuromuscular blocking agent with an intermediate duration of action devoid of significant adverse effects previously used in pigs with a wide dosage range. Cis‐atracurium was administered at 1 mg/kg bolus to sixteen pigs to establish its time profile and effects. The pigs were premedicated intramuscularly with 4 mg/kg azaperone, 8 mg/kg ketamine and 0.2 mg/kg morphine IM and maintained with isoflurane in oxygen. After cis‐atracurium administration, neuromuscular monitoring via acceleromyography was started until the recovery of the 90% of the train of four ratio. Complete decrease in the train of four ratio was accomplished in eleven pigs. Onset of action was 70 s, with a recovery of the fourth twitch at 26 min and a recovery of a train of four ratio greater than 90% in 60 min. In conclusion, 1 mg/kg intravenous cis‐atracurium in the pig allowed for a rapid onset of action and a complete recovery after 60 min although high variability in the time profile is seen.     

The efficacy of an albendazole-medicated block in controlling sheep nematodes in Xinjiang Province,north-west China

Medicated feed-blocks containing 2 mg/kg albendazole were fed for 12 days to ewe-lambs naturally infected with nematode worms in north-west China. The cumulative total average intake of albendazole was 15 mg/kg body weight. This treatment was compared with a single oral drench of 15 mg/kg albendazole and with no treatment. Both albendazole treatments were 99% effective in reducing the total strongyle egg counts. The medicated block was 100% effective in reducing the total trichostrongylid worm count, although only 86.4% of the sheep consumed an adequate amount. The single drench was 97% effective. Under the management conditions available to sheep herders in the northern provinces of China, albendazole-medicated feed-blocks used at strategic times could effectively control trichostrongylid nematodes.     

Atracurium as an Adjunct to Halothane-Oxygen Anesthesia in a Llama Undergoing Intraocular Surgery A Case Report

Atracurium (0.2 mg/kg intravenously [IV]) was administered to a llama anesthetized with halothane in oxygen, to insure immobilization of the globe during intraocular surgery. Recovery of neuromuscular function was facilitated by administration of edrophonium (0.5 mg/kg IV).     

Neuromuscular and cardiovascular effects of atracurium in isoflurane-anesthetized chickens.

Atracurium besylate, a nondepolarizing neuromuscular blocking agent, was administered to 24 isoflurane-anesthetized domestic chickens. Birds were randomly assigned to 4 groups, and atracurium was administered at dosage of 0.15, 0.25, 0.35 or 0.45 mg/kg of body weight. The time of onset of twitch depression, the amount of maximal twitch depression, and the duration of muscular relaxation were recorded. After return to control twitch height, atracurium was further administered to achieve > 75% twitch depression. When twitch depression reached 75% during noninduced recovery, 0.5 mg of edrophonium/kg was administered to reverse the muscle relaxation. Throughout the experimental period, cardiovascular, arterial blood gas, and acid-base variables were monitored. The effective dosage of atracurium to result in 95% twitch depression in 50% of birds, (ED95/50) was calculated, using probit analysis, to be 0.25 mg/kg, whereas the ED95/95, the dosage of atracurium to result in 95% twitch depression in 95% of birds, was calculated by probit analysis to be 0.46 mg/kg. The total duration of action at dosage of 0.25 mg/kg was 34.5 +/- 5.8 minutes; at the highest dosage (0.45 mg/kg), total duration increased to 47.8 +/- 10.3 minutes. The return to control twitch height was greatly hastened by administration of edrophonium. Small, but statistically significant changes in heart rate and systolic blood pressure, were associated with administration of atracurium and edrophonium. These changes would not be clinically relevant. In this study, atracurium was found to be safe and reliable for induction of muscle relaxation in isoflurane-anesthetized chickens.     

Interactions between pipecuronium and suxamethonium in the dog

The depolarising muscle relaxant suxamethonium (0.3 mg kg-1) and the non-depolarising muscle relaxant pipecuronium (0.05 mg kg-1) were administered to four dogs. In the first series of experiments pipecuronium was administered intravenously, followed at 50 per cent of return of neuromuscular activity by suxamethonium. At 50 per cent return of activity atropine and neostigmine were administered to reverse the neuromuscular block. In the second series the sequence was reversed and pipecuronium was administered after suxamethonium. At 50 per cent recovery atropine and neostigmine were given. In the first series of experiments the time for the onset of suxamethonium block was significantly increased after prior administration of pipecuronium. However, in the second series of experiments the prior administration of suxamethonium had no significant effect on the duration of action of pipecuronium.     

Preliminary studies on the effectiveness of the novel pulicide, spinosad, for the treatment and control of fleas on dogs

Spinosad is a novel mode-of-action insecticide produced from a family of natural products derived from fermentation of the actinomycete, Saccharopolyspora spinosa. Separate studies were undertaken to determine the minimum effective dose of spinosad given orally for the treatment of experimentally induced flea infestations (Ctenocephalides felis) on dogs, and to assess any potential impacts of feeding canned or dry food at the time of dosing. Both were randomized block (blocked by gender and pre-treatment flea counts), blinded parallel-arm studies, with dogs selected on health and ability to maintain pre-treatment flea populations. For dose selection, 48 dogs were allocated among six groups (8 dogs/group; 4 males, 4 females): placebo-treated negative control, spinosad in gelatin capsules at 15, 20, 30 and 40 mg/kg administered per os; and topical imidacloprid (10 mg/kg) as a positive control. Placebo and spinosad treatments were administered on Days 0, 30 and 60, imidacloprid only on Day 0. In a second study to assess the impact of food type at the time of dosing, three groups were formed: placebo-treated control (8 dogs; 4 males, 4 females), spinosad (30 mg/kg) administered with canned food (8 male dogs, 8 females); and spinosad (30 mg/kg) with dry food (8 males, 8 females). Treatments were administered on Days 0 and 30. To assess post-treatment persistent efficacy, flea infestations were repeated at regular post-treatment intervals, beginning on Day 5 through Day 89 in the dose selection study and Day 58 in the impact of food type and dosing study. Flea counts were performed 48 h post-infestation by study personnel who were blinded to treatments. In the dose selection study, compared to geometric mean live flea counts in the control group, each spinosad dose was highly effective (99.8–100%) at 7, 14 and 21 days after treatment. Only the 30 and 40 mg/kg doses maintained high efficacy (97.2–100%) until 30 days after treatment, with no difference between the two. Imidacloprid was highly effective at Day 30, with significant difference only from the 15 mg/kg spinosad group. Because there was no significant difference between the higher spinosad rates, 30 mg/kg was selected as the optimal minimum effective dose. In the second study, spinosad was highly effective at all post-treatment flea counts (98–100%). Taken together, these studies demonstrate that repeated monthly oral treatments with spinosad at 30 mg/kg provide sustained control of C. felis on dogs. There were no treatment-related adverse events in either study, indicating that spinosad has potential to be used monthly as a safe and effective flea adulticide, providing sustained activity that matches that of currently used topical products.     

Curing experimental Bryophyllum tubiflorum poisoning of cattle with activated carbon, electrolyte replacement solution and antiarrhythmic drugs

A slurry of activated carbon (activated charcoal) in electrolyte replacement solution given by stomach tube and antiarrhythmic drugs given parenterally cured 9 of 11 calves dosed 7 to 24 h previously with a lethal amount (20g/kg) of Bryophyllum tubiflorum flower heads. Two of another 4 calves treated 26 to 36 h after dosing with flowers survived. B. tubiflorum toxins are bufadienolides (cardiac glycosides). Activated carbon was effective at a single dose of 5 g/kg. Calves were rehydrated with oral electrolyte replacement solution at 150 ml/kg in divided doses over 24 h. Tachycardia was treated with intravenous lignocaine (200 mg doses) or propranolol (5 mg doses) and atrioventricular block with atropine (0.5 mg/kg).     

Evaluation of the analgesic effect of lidocaine and bupivacaine used to provide a brachial plexus block for forelimb surgery in 10 dogs

Twenty adult dogs weighing between 1.4 and 53.5 kg and aged between six months and nine years were anaesthetised and the brachial plexus was localised with the aid of a nerve stimulator. In 10 of the dogs a brachial plexus block was induced with a mixture of lidocaine and bupivacaine and the other 10 each received 0.25 ml/kg saline as a control. The end-tidal isoflurane concentration was maintained between 1.3 and 1.4 per cent during surgery for carpal arthrodesis or a fracture of the radius or ulna. Acute heart rate or blood pressure increases of 20 per cent or more were treated with 1 microg/kg fentanyl intravenously. Postoperatively, signs of pain were scored by a single blinded observer at hourly intervals until eight hours after the block had been induced, on a scale from 0 to 18. Dogs with pain scores above 5 received 0.1 to 0.2 mg/kg methadone intravenously, repeated as necessary. During surgery the control dogs received significantly more fentanyl (median 0.05 microg/kg/minute, range 0.02 to 0.20 microg/kg/minute) than the group given local anaesthetic (median 0 microg/kg/minute, range 0 to 0.02 microg/kg/minute). Postoperatively, the control group required significantly more methadone (median 0.2 mg/kg, range 0.1 to 1 mg/kg) than the treated group (median 0 mg/kg, range 0 to 0.13 mg/kg).     

Recovery from neuromuscular block in dogs: restoration of spontaneous ventilation does not exclude residual blockade

ObjectiveTo evaluate if return of spontaneous ventilation to pre-relaxation values indicates complete recovery from neuromuscular blockade.Study designProspective, with each individual acting as its own control.AnimalsTen healthy adult female Beagle dogs weighing 6.2–9.4 kg.MethodsDogs were anesthetized with propofol, dexemedetomidine and isoflurane. Spontaneous ventilation was assessed by measuring end-tidal CO₂, expired tidal volume, peak inspiratory flow, respiratory rate and minute ventilation. Vecuronium 25 μg kg^?1 IV was administered and neuromuscular block was evaluated by measuring the train-of-four (TOF) ratio with acceleromyography in the hind limb. During spontaneous recovery from neuromuscular block, the TOF ratio when each ventilatory variable returned to baseline was recorded.ResultsThis dose of vecuronium produced moderate neuromuscular block in all dogs, with TOF ratio values of 0–18% at maximal block. Expired tidal volume, peak inspiratory flow and minute ventilation returned to pre-relaxation values when the median TOF ratio was ≤ 20%. The median TOF ratio was 42% when the end-tidal CO₂ returned to pre-relaxation values.Conclusions and clinical relevanceSignificant residual neuromuscular block could be measured at the hind limb with acceleromyography when ventilation had spontaneously returned to pre-vecuronium values. Monitoring spontaneous ventilation, including end-tidal CO₂, expired tidal volume, peak inspiratory flow or minute ventilation cannot be used as a surrogate for objective neuromuscular monitoring, and this practice may increase the risk of postoperative residual paralysis.