Determination of the sevoflurane sparing effect of methadone in cats

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Romifidine or xylazine combined with ketamine in dogs premedicated with methotrimeprazine

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effects of buprenorphine, carprofen and saline on thermal and mechanical nociceptive thresholds in cats

To evaluate a prototype pressure stimulus device for use in the cat and to compare with a known thermal threshold device.Eight healthy adult cats weighing between 3.0 and 4.9 kg.Pressure stimulation was given via a plastic bracelet taped around the forearm. Three 2.4 mm diameter ball bearings, in a 10-mm triangle, were advanced against the craniolateral surface of the antebrachium by manual inflation of a modified blood pressure bladder. Pressure in the cuff was recorded at the end point (leg shake and head turn). Thermal threshold was also tested. Stimuli were stopped if they reached 55 degrees C or 450 mmHg without response. After four pressure and thermal threshold baselines, each cat received SC buprenorphine 0.01 mg kg(-1), carprofen 4 mg kg(-1) or saline 0.3 mL in a three period cross-over study with a 1-week interval. The investigator was blinded to the treatment. Measurements were made at 0.25. 0.5, 0.75, 1, 2, 3, 4, 6, 8, and 24 hours after injection. Data were analyzed by using ANOVA.There were no significant changes in thermal or pressure threshold after administration of saline or carprofen, but thermal threshold increased from 60 minutes until 8 hours after administration of buprenorphine (p < 0.05). The maximum increase in threshold from baseline (Delta T-max) was 3.5 +/- 3.1 degrees C at 2 hours. Pressure threshold increased 2 hours after administration of buprenorphine (p < 0.05) when the increase in threshold above baseline (Delta P-max) was 162 +/- 189 mmHg.This pressure device resulted in thresholds that were affected by analgesic treatment in a similar manner but to a lesser degree than the thermal method. Pressure stimulation may be a useful additional method for analgesic studies in cats.

Anestesia epidural com ropivacaína, lidocaína ou associação de lidocaína e xilazina em cães: efeitos cardiorrespiratório e analgésico

Este estudo investigou o efeito da ropivacaína, da lidocaína e da associação de lidocaína e xilazina na anestesia epidural de cães. Trinta cães foram tranqüilizados com acepromazina intravenosa, distribuídos em três grupos e submetidos à anestesia epidural no espaço lombo-sacro, com lidocaína 2% com vasoconstrictor (GL), ropivacaína 1% (GR) ou com xilazina associada à lidocaína (GXL). Mensuraram-se as freqüências cardíaca (FC) e respiratória (f), a pressão arterial sistólica (PAS), a concentração final expirada de CO2 (EtCO2), o volume minuto (VM) e a temperatura retal (T). Para avaliação da analgesia somática, utilizou-se o teste do panículo e o teste térmico a 55°C. Os protocolos produziram anestesia da região retro-umbilical, sendo que a associação XL produziu bloqueio anestésico mais cranial, porém causou bradicardia moderada. A duração da anestesia foi mais prolongada nos animais dos grupos GXL (240 min) e GR (250 min), quando comparada as do grupo GL (120 min).

Effects of methadone on the minimum alveolar concentration of isoflurane in dogs

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Comparative study on the sedative effects of morphine, methadone, butorphanol or tramadol, in combination with acepromazine, in dogs

To compare the effects of morphine (MOR), methadone (MET), butorphanol (BUT) and tramadol (TRA), in combination with acepromazine, on sedation, cardiorespiratory variables, body temperature and incidence of emesis in dogs.Prospective randomized, blinded, experimental trial.Six adult mixed-breed male dogs weighing 12.0 +/- 4.3 kg.Dogs received intravenous administration (IV) of acepromazine (0.05 mg kg(-1)) and 15 minutes later, one of four opioids was randomly administered IV in a cross-over design, with at least 1-week intervals. Dogs then received MOR 0.5 mg kg(-1); MET 0.5 mg kg(-1); BUT 0.15 mg kg(-1); or TRA 2.0 mg kg(-1). Indirect systolic arterial pressure (SAP), heart rate (HR), respiratory rate (f(R)), rectal temperature, pedal withdrawal reflex and sedation were evaluated at regular intervals for 90 minutes.Acepromazine administration decreased SAP, HR and temperature and produced mild sedation. All opioids further decreased temperature and MOR, BUT and TRA were associated with further decreases in HR. Tramadol decreased SAP whereas BUT decreased f(R) compared with values before opioid administration. Retching was observed in five of six dogs and vomiting occurred in one dog in MOR, but not in any dog in the remaining treatments. Sedation scores were greater in MET followed by MOR and BUT. Tramadol was associated with minor changes in sedation produced by acepromazine alone.When used with acepromazine, MET appears to provide better sedation than MOR, BUT and TRA. If vomiting is to be avoided, MET, BUT and TRA may be better options than MOR.

Effects of methadone, alone or in combination with acepromazine or xylazine, on sedation and physiologic values in dogs

Objective To evaluate the effects of methadone, administered alone or in combination with acepromazine or xylazine, on sedation and on physiologic values in dogs.Study design Randomized cross-over design.Animals Six adult healthy mixed-breed dogs weighing 13.5 +/- 4.9 kg.Methods Dogs were injected intramuscularly with physiologic saline (Control), or methadone (0.5mg kg(-1)) or acepromazine (0.1 mg kg(-1)) or xylazine (1.0 mg kg(-1)), or acepromazine (0.05 mg kg(-1)) plus methadone (0.5 mg kg(-1)) or xylazine (0.5 mg kg(-1)) plus methadone (0.5 mg kg(-1)) in a randomized cross-over design, with at least 1-week intervals. Sedation, pulse rate, indirect systolic arterial pressure, respiratory rate (RR), body temperature and pedal withdrawal reflex were evaluated before and at 15-minute intervals for 90 minutes after treatment.Results Sedation was greater in dogs receiving xylazine alone, xylazine plus methadone and acepromazine plus methadone. Peak sedative effect occurred within 30 minutes of treatment administration. Pulse rate was lower in dogs that received xylazine either alone or with methadone during most of the study. Systolic arterial pressure decreased only in dogs receiving acepromazine alone. When methadone was administered alone, RR was higher than in other treatments during most of the study and a high prevalence of panting was observed. In all treatments body temperature decreased, this effect being more pronounced in dogs receiving methadone alone or in combination with acepromazine. Pedal withdrawal reflex was absent in four dogs receiving methadone plus xylazine but not in any dog in the remaining treatments.Conclusions Methadone alone produces mild sedation and a high prevalence of panting. Greater sedation was achieved when methadone was used in combination with acepromazine or xylazine. The combination xylazine-methadone appears to result in better analgesia than xylazine administered alone. Both combinations of methadone/sedative were considered effective for premedication in dogs.

Effects of meperidine or saline on thermal, mechanical and electrical nociceptive thresholds in cats

Objective To measure cutaneous electrical nociceptive thresholds in relation to known thermal and mechanical stimulation for nociceptive threshold detection in cats.Study design Prospective, blinded, randomized cross-over study with 1-week washout interval.Animals Eight adult cats [bodyweight 5.1 +/- 1.8 kg (mean + SD)].Methods Mechanical nociceptive thresholds were tested using a step-wise manual inflation of a modified blood pressure bladder attached to the cat's thoracic limb. Thermal nociceptive thresholds were measured by increasing the temperature of a probe placed on the thorax. The electrical nociceptive threshold was tested using an escalating current from a constant current generator passed between electrodes placed on the thoracic region. A positive response (threshold) was recorded when cats displayed any or all of the following behaviors: leg shake, head turn, avoidance, or vocalization. Four baseline readings were performed before intramuscular injection of meperidine (5 mg kg(-1)) or an equal volume of saline. Threshold recordings with each modality were made at 15, 30, 45, 60, 90, and 120 minutes post-injection. Data were analyzed using ANOVA and paired t-tests (significance at p < 0.05).Results There were no significant changes in thermal, mechanical, or electrical thresholds after saline. Thermal thresholds increased at 15-60 minutes (p < 0.01) and mechanical threshold increased at 30 and 45 minutes after meperidine (p < 0.05). Maximum thermal threshold was +4.1 +/- 0.3 degrees C above baseline at 15 minutes while maximum mechanical threshold was 296 +/- 265 mmHg above baseline at 30 minutes after meperidine. Electrical thresholds following meperidine were not significantly different than baseline (p > 0.05). Thermal and electrical thresholds after meperidine were significantly higher than saline at 30 and 45 minutes (p < 0.05), and at 120 minutes (p < 0.05), respectively. Mechanical thresholds were significantly higher than saline treatment at 30 minutes (p <= 0.05).Conclusion and clinical relevance Electrical stimulation did not detect meperidine analgesia whereas both thermal and mechanical thresholds changed after meperidine administration in cats.

Post-operative analgesic effects of butorphanol or firocoxib administered to dogs undergoing elective ovariohysterectomy

ObjectiveTo compare the post-operative analgesic effects of butorphanol or firocoxib in dogs undergoing ovariohysterectomy.Study designProspective, randomized, blinded, clinical trial.AnimalsTwenty-five dogs > 1 year of age.MethodsDogs received acepromazine intramuscularly (IM), 0.05 mg kg-1 and either butorphanol IM, 0.2 mg kg-1 (BG, n = 12) or firocoxib orally (PO), 5 mg kg-1 (FG, n = 13), approximately 30 minutes before induction of anesthesia with propofol. Anesthesia was maintained with isoflurane. Ovariohysterectomy was performed by the same surgeon. Pain scores using the dynamic and interactive visual analog scale (DIVAS) were performed before and at 1, 2, 3, 4, 6, 8 and 20 hours after the end of surgery by one observer, blinded to the treatment. Rescue analgesia was provided with morphine (0.5 mg kg-1) IM and firocoxib, 5 mg kg-1 (BG only) PO if DIVAS > 50. Groups were compared using paired t-tests and Fisher's exact test (p < 0.05). Data are presented as mean +/- SD.ResultsThe BG required significantly less propofol (BG: 2.6 +/- 0.59 mg kg-1; FG: 5.39 +/- 0.7 mg kg-1) (p < 0.05) but the anesthesia time was longer (BG: 14 +/- 6, FG: 10 +/- 4 minutes). There were no differences for body weight (BG: 7.9 +/- 5.0, FG: 11.5 +/- 4.6 kg), sedation scores, and surgery and extubation times (BG: 10 +/- 2, 8 +/- 5 minutes; FG: 9 +/- 3, 8 +/- 4 minutes, respectively) (p > 0.05). The FG had significantly lower pain scores than the BG at 1, 2 and 3 hours following surgery (p < 0.05). Rescue analgesia was administered to 11/12 (92%) and 2/13 (15%) dogs in the BG and FG, respectively (p < 0.05).Conclusion and clinical relevanceFirocoxib produced better post-operative analgesia than butorphanol. Firocoxib may be used as part of a multimodal analgesia protocol but may not be effective as a sole analgesic.

Postoperative analgesic effects of intravenous, intramuscular, subcutaneous or oral transmucosal buprenorphine administered to cats undergoing ovariohysterectomy

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Electroacupuncture analgesia in dogs: is there a difference between uni- and bi-lateral stimulation?

Objective To compare the analgesic effect of uni- and bi-lateral electroacupuncture (EA) in response to thermal and mechanical nociceptive stimuli and to investigate the cardiorespiratory, endocrine, and behavioral changes in dogs submitted to EA.Study design Prospective, randomized cross-over experimental study.Animals Eight adult, clinically healthy, cross-breed dogs, weighing 13 +/- 4 kg.Methods Dogs underwent electrostimulation at false acupoints (T-false); bilateral EA at acupoints, stomach 36, gall bladder 34 and spleen 6 (T-EA/bil); unilateral EA at the same points (T-EA/uni) or were untreated (T-control). All animals received acepromazine (0.05 mg kg(-1)) IV; and heart rate, pulse oximetry, indirect arterial blood pressure, respiratory rate, PECO2, rectal temperature, and plasma cortisol concentration were measured before, during, and after EA. Analgesia was tested using thoracic and abdominal cutaneous thermal and mechanical stimuli, and an interdigital thermal stimulus. Behavior was classified as calm or restless. Analysis of variance for repeated measures followed by Tukey's test was used for analysis of the data.Results There were no cardiorespiratory differences among the treatments. The cutaneous pain threshold was higher after EA, compared with false points. The latency period was shorter and analgesia was more intense in T-EA/bil than T-EA/uni, when both were compared with T-false and T-control. Six out of eight animals treated with EA were calm during treatment, and 5/8 and 4/8 of the T-false and T-control animals, respectively, were restless. Latency to interdigital thermal stimulation increased in T-EA/bil compared with the others. There was no difference in plasma cortisol concentrations among the treatments.Conclusions Bilateral EA produced a shorter latency period, a greater intensity, and longer duration of analgesia than unilateral stimulation, without stimulating a stress response.Clinical relevance Bilateral EA produces a better analgesic effect than unilateral EA.

Effect of intravenous propofol and remifentanil on heart rate, blood pressure and nociceptive response in acepromazine premedicated dogs

ObjectiveTo investigate the cardiorespiratory, nociceptive and endocrine effects of the combination of propofol and remifentanil, in dogs sedated with acepromazine.Study designProspective randomized, blinded, cross-over experimental trial.AnimalsTwelve healthy adult female cross-breed dogs, mean weight 18.4 +/- 2.3 kg.MethodsDogs were sedated with intravenous (IV) acepromazine (0.05 mg kg-1) followed by induction of anesthesia with IV propofol (5 mg kg-1). Anesthesia was maintained with IV propofol (0.2 mg kg-1 minute-1) and remifentanil, infused as follows: R1, 0.125 mu g kg-1 minute-1; R2, 0.25 mu g kg-1 minute-1; and R3, 0.5 mu g kg-1 minute-1. The same dogs were administered each dose of remifentanil at 1-week intervals. Heart rate (HR), mean arterial pressure (MAP), respiratory rate (f(R)), end tidal CO(2) (Pe'CO(2)), arterial hemoglobin O(2) saturation, blood gases, and rectal temperature were measured before induction, and 5, 15, 30, 45, 60, 75, 90, and 120 minutes after beginning the infusion. Nociceptive response was investigated by electrical stimulus (50 V, 5 Hz and 10 ms). Blood samples were collected for plasma cortisol measurements. Statistical analysis was performed by anova (p < 0.05).ResultsIn all treatments, HR decreased during anesthesia with increasing doses of remifentanil, and increased significantly immediately after the end of infusion. MAP remained stable during anesthesia (72-98 mmHg). Antinociception was proportional to the remifentanil infusion dose, and was considered satisfactory only with R2 and R3. Plasma cortisol concentration decreased during anesthesia in all treatments. Recovery was smooth and fast in all dogs.Conclusions and clinical relevanceInfusion of 0.25-0.5 mu g kg-1 minute-1 remifentanil combined with 0.2 mg kg-1 minute-1 propofol produced little effect on arterial blood pressure and led to a good recovery. The analgesia produced was sufficient to control the nociceptive response applied by electrical stimulation, suggesting that it may be appropriate for performing surgery.

Effect of lidocaine on the minimum alveolar concentration of sevoflurane in dogs

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Ropivacaína isolada e associada ao fentanil ou ao tramadol administrados pela via peridural em cães

A anestesia peridural é amplamente difundida no meio veterinário, utilizando-se o anestésico local isolado ou associado aos opióides, capazes de promover aumento do efeito analgésico. O objetivo deste estudo foi avaliar a função cardiorrespiratória e analgésica da ropivacaína isolada ou associada ao fentanil ou tramadol. Para tanto, oito cães foram tranqüilizados com acepromazina, submetidos à anestesia peridural com um dos seguintes protocolos: GR (ropivacaína), GRF (ropivacaína + fentanil), GRT (ropivacaína + tramadol), em volume total de 0,25ml kg-1, e foram avaliados os parâmetros: freqüência cardíaca e respiratória, temperatura retal, pressão arterial sistólica, e gasometria do sangue arterial, os bloqueios sensitivo e motor, o grau de sedação e a ocorrência de possíveis efeitos indesejáveis. A diminuição da freqüência cardíaca nos grupos GRF e GRT foi mais intensa e ocorreu hipotermia significativa no GRF. Foi evidenciada sedação severa em GRF e GRT. O período de recuperação foi mais curto nos animais de GRT. O GRT foi o grupo que apresentou bloqueio mais cranial. Foram observadas bradicardia, hipotermia e síndrome de Shiff-Sherrington no período trans-anestésico em animais de todos os grupos. Nas 24 horas de período pós-anestésico, não foram evidenciados efeitos indesejáveis nos grupos. O GRF apresentou maior duração de anestesia e analgesia, enquanto que o GRT apresentou a menor duração de anestesia com analgesia intermediária e o GR apresentou duração intermediária, com menor analgesia. Não foram encontradas alterações respiratórias e hemogasométricas, porém, bradicardia, hipotermia e síndrome de Schiff-Sherrington, alterações trans-anestésicas comuns na anestesia peridural foram encontradas.