Epidurally administered neostigmine reduced the use of supplemental analgesia after ovariohysterectomy in dogs. However, analgesic effects were less pronounced than for epidurally administered morphine or morphine-neostigmine. Adding neostigmine to epidurally administered morphine did not potentiate opioid-induced analgesia.

PURPOSE: To evaluate hemodynamics and bispectral index (BIS) in bitches anesthetized with ketamine and midazolam in combination with dexmedetomidine or medetomidine and submitted to ovariohysterectomy. METHODS: Twenty bitches pretreated with levomedetomidine and buprenorphine were anesthetized with 5 mg.kg-1 ketamine and 0.2 mg.kg-1 midazolam i.v. Continuous infusion of 0.4 mg.kg-1.h-1 midazolam and 20 mg.kg-1.h-1 ketamine was initiated in combination with DEX (n=10): 20 µg.kg-1.h-1 dexmedetomidine or MED (n=10): 30 µg.kg-1.h-1 medetomidine over 30 minutes. A pharmacokinetic study provided dexmedetomidine plasma concentration, set to be 3.0 ng.mL-1. RESULTS: BIS decreased in both groups (P<0.05), but it was lower in DEX (P<0.05) as compared to MED. No differences were found in hemodynamic parameters (heart rate, systolic, diastolic and mean arterial pressure) between groups (P>0.05), but heart rate decreased in both groups, as compared to control values (P<0.05). Respiratory rate decreased (P<0.05) and expired end tidal CO2 increased progressively (P<0.05) and similarly in both groups. Anesthetic recovery period was similar between groups (P<0.05) with no adverse effects. CONCLUSION: Continuous administration of dexmedetomidine with calculated plasma concentration equal to 3 ng.mL-1 in combination with midazolam and ketamine provides suitable anesthesia for spay surgery in bitches, hemodynamic stability and calm awakening with no adverse effects.

PURPOSE: To compare two propofol infusion techniques in bitches subjected to ovaryhisterectomy by estimating the efficiency of the propofol target-dose, evaluating the cardiorespiratory and hemogasimetric attributes, and the bispectral scale index (BIS) as well as the recovery period characteristics. METHODS: Twenty anesthetized bitches were divided into two groups of 10 each (G1, G2). Animals of G1 were pre-treated with methotrimeprazine and anesthetized with target-controlled propofol infusion by means of a Harvard infusion pump combined to remifentanil through a syringe pump. RESULTS: Bradycardia and light hypotension, hemogasimetric and respiratory stability besides a good myorelaxation, more evident during continuous infusion and good hypnosis. CONCLUSIONS: Dosis used in both techniques, after methotrimeprazine pre-treatment and combined to the opioid, were efficient for the surgery. The target-controlled anesthesia required a smaller anesthetic consumption (propofol) with faster recovery periods.

Purpose:To evaluate the parameters of dogs anesthetized by different dissociative drugs protocols through continuous intravenous infusion. Methods: Thirty healthy dogs of both sexes were assigned randomly to three groups (G1, G2, and G3). G1 was administered with methotrimeprazine as a pre-anesthetic medication, intravenously midazolam-ketamine as bolus for induction and midazolam-ketamine by continuous intravenous infusion for a 60 minute-period of maintenance. G2: the same as for G1. plus an increase in the midazolam dose during maintenance. G3: the same treatment as for G2, plus the addition of xylazine during maintenance. Immediately after induction the anesthetic maintenance started, and measures were taken 15 minutes after pre-medication, at 10 minutes intervals, during maintenance (M0 to M7). Results: Bradycardia, atrioventricular blockage, bradypnea and hypoxemia were shown in G3. G1 and G2 showed a slight hypotension only. Conclusion: There were some advantages by using the continuous intravenous via: no parameters oscillation and reduction in the anesthetic recovery period. The increase in midazolam dose brought about little parametric variations which were greater when xylazine was used, with a consequent hypoxemia, bradyarrhytmia, and decrease in respiratory frequency and minute volume. Key words: Anesthesia. Methotrimeprazine. Midazolam. Xylazine. Dogs. RESUMOObjetivo: Avaliar os parâmetros de cães anestesiados com diferentes protocolos de fármacos dissociativos por infusão intravenosa contínua. Métodos: Foram utilizados 30 cães, machos e fêmeas, clinicamente sadios, distribuídos aleatoriamente em três grupos (G1,G2 e G3) (*)). Em G1 utilizou-se levomepromazina como medicação pré-anestésica (MPA), midazolamcetamina pela via intravenosa em bolus para indução e midazolam-cetamina em infusão intravenosa contínua por 60 minutos para manutenção. Em G2 procedeu-se da mesma forma que em G1 elevando-se, porém, a dose de midazolam durante a manutenção. Em G3 repetiu-se o tratamento empregado em G2, acrescentando-se a xilazina à manutenção. Após a indução, iniciou-se imediatamente a manutenção anestésica, realizando-se aferições, 15 minutos depois da MPA, em intervalos de 10 minutos, durante a manutenção (M0 a M7). Resultados: Em G3 ocorreu bradicardia, bloqueio átrio-ventricular, bradipnéia e hipoxemia e em G1 e G2, discreta hipotensão. Conclusão: A via intravenosa contínua apresentou vantagens quanto a: não oscilação dos parâmetros e redução no período de recuperação anestésica. A elevação da dose de midazolam resultou em discretas variações paramétricas, estas, acentuadas pelo uso da xilazina, que causou hipoxemia, bradiarritmia, diminuição da freqüência respiratória e volume minuto.

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PURPOSE: To compare, by continuous infusion of ketamine or medetomidine combined to methotrimeprazine and buprenorphine, ketamine and midazolam, the degree of hypnosis, myorelaxation, anesthetic quality and surgical feasibility through evaluation of possible parametric alterations and recovery quality. METHODS: 20 healthy adult females dogs, aged 3 to 5 years, body weight between 7 and 15 kg, were assigned randomly and homogenously to 2 groups of 10 animals each (n=10), group 1 (G1) and group 2 (G2), respectively. Animals of G1 were subjected to a pre-treatment with intravenous 1.0 mg/kg methotrimeprazine and or 3ì/kg. After 15 minutes, a 5.0 mg/kg ketamine and 0.2 mg/kg midazolam were intravenously injected. Immediately after induction, an anesthetic combination of 0.4 mg/kg/h midazolam, 20 mg/kg/h ketamine and 1.0 mg/kg/h xylazine, was continuously and intravenously administered for 30 minutes. The same techniques were used in G2 except for the substitution of xylazine for 30ìg/kg/h medetomidine. RESULTS: In G1 there was a 1st and 2nd degree atrioventricular heart block, a longer recovery period and lower quality. In G2 a 1st degree atrioventricular heart block occurred but isolated and ephemeral. CONCLUSIONS: The continuous infusion method, besides reducing drugs utilization, prevented collateral effects allowing a more tranquil recovery with no excitations, both protocols permitted the surgical procedure (ovary-hysterectomy) bringing about a reduction in hypnosis and an accentuated myorelaxation. Xylazine and medetomidine showed a similar pharmacodynamic behavior but with different clinical aspects. The electrocardiographic alterations observed in G2 and in a lower degree in G1 must be well studied. Describers: dogs, ketamine, methotrimeprazine, medetomidine, midazolam and xylazine.