Influence of intravenous fentanyl or dexmedetomidine infusions, combined with lidocaine and ketamine, on cardiovascular response, sevoflurane requirement and postoperative pain in dogs anesthetized for unilateral mastectomy.

OBJECTIVE: To compare the effects of constant rate infusions (CRI) of fentanyl or dexmedetomidine, combined with lidocaine and ketamine, on cardiovascular response during surgery, sevoflurane requirement and postoperative pain in dogs undergoing mastectomy. STUDY DESIGN: Prospective, randomized, blinded, clinical trial. ANIMALS: A total of 29 female dogs with mammary tumors. METHODS: Premedication consisted of intramuscular acepromazine and morphine. General anesthesia was induced with intravenous propofol and maintained with sevoflurane. Dogs were randomized to be administered intravenous DLK [dexmedetomidine 1 µg kg-1 loading dose (LD) and 1 µg kg-1 hour-1; lidocaine 2 mg kg-1 LD and 3 mg kg-1 hour-1; ketamine 1 mg kg-1 LD and 0.6 mg kg-1 hour-1; n = 14] or FLK (fentanyl 5 µg kg-1 LD and 9 µg kg-1 hour-1; same doses of lidocaine and ketamine; n = 15) during anesthesia. Cardiorespiratory variables and end-tidal sevoflurane (Fe'Sevo) were recorded during surgery. The number of dogs administered ephedrine to treat arterial hypotension [mean arterial pressure (MAP) < 60 mmHg] was recorded. Meloxicam was administered to both groups. Postoperative pain and rescue analgesia requirement were assessed for 24 hours using the short form of the Glasgow Composite Measure Pain Scale. Data were compared using a mixed effects model or a Mann-Whitney test. RESULTS: More dogs required ephedrine in FLK than in DLK (67% versus 7%). Heart rate was not significantly different between groups, whereas lower values of MAP (p ≤ 0.01) and Fe'Sevo (p = 0.018) were observed in FLK than in DLK. Rescue analgesia was administered to 2/15 dogs in FLK and 0/14 dogs in DLK. CONCLUSIONS AND CLINICAL RELEVANCE: Based on the cardiovascular response during surgery, intraoperative infusions of FLK and DLK provided adequate antinociception. Infusion of DLK provided greater stability of blood pressure. Both protocols resulted in minimal need for additional analgesia within 24 hours postoperatively.

Agreement between hematocrit values determined by the Cobas b121 blood gas analyzer and the microhematocrit method in dogs, cats, and horses.

BACKGROUND: Packed cell volume (PCV) is important for assessing a patient's health status. Some blood gas analyzers measure hematocrit, and the agreement with PCV varies among different analyzers. OBJECTIVES: We aimed to determine the agreement between PCV measured by microcentrifugation and hematocrit measured by the Cobas b121 blood gas analyzer in dogs, cats, and horses. METHODS: Whole blood samples for PCV and blood gas analysis were collected in lithium-heparin syringes and analyzed within 10 min of collection. Agreement and association between the PCV and Cobas b121 generated hematocrit were assessed by the Bland-Altman method, Pearson's correlation, Deming regression analysis, and paired t tests. A total allowable error of 10% was used for the analysis. RESULTS: This study included 45 dogs, 45 cats, and 33 horses. The respective mean ± SD (minimum-maximum) of PCVs and hematocrits were: dogs, 34.9 ± 9.9% (9.0-55.0) and 32.5 ± 8.8% (10.4-50.6); cats, 29.0 ± 9.6% (11.0-51.0) and 26.9 ± 9.3% (10.2-50.9); horses, 34.2 ± 6.5% (24.0-47.0) and 34.1 ± 6.0% (22.5-46.1). There were no significant differences between the methods. The bias ± SD was: dogs, -2.4 ± 2.6%; cats, -2.2 ± 2.3%; horses, -0.1 ± 2.4%. Pearson's correlation coefficients were > 0.90 for all species (P < 0.0001). In 60%, 49%, and 85% of the samples for dogs, cats, and horses, respectively, the percentage differences between the methods were within 10%. CONCLUSIONS: The Cobas b121 blood gas analyzer provided accurate estimates of PCVs in horses. However, in dogs and cats, there was a large frequency of unacceptable differences between the methods.

Influence of Constant Rate Infusions of Fentanyl Alone or in Combination With Lidocaine and Ketamine on the Response to Surgery and Postoperative Pain in Isoflurane Anesthetized Dogs Undergoing Unilateral Mastectomy: A Randomized Clinical Trial.

The aim of this study was to compare the effects of constant rate infusions (CRI) of fentanyl alone or combined with lidocaine and ketamine (FLK), on physiological parameters, isoflurane requirements and the number of postoperative analgesic rescues in dogs undergoing unilateral mastectomy. Twenty-two dogs were premedicated with acepromazine 0.02 mg/kg and morphine 0.5 mg/kg and anesthetized with propofol and isoflurane. Dogs were randomly assigned to 1 of 2 groups: Fentanyl group (fentanyl 5 µg/kg loading dose [LD] and 9 µg/kg/h CRI; n = 11); FLK group (fentanyl [same doses]; lidocaine 2 mg/kg LD and 3 mg/kg/h CRI; ketamine 1.0 mg/kg LD and 0.6 mg/kg/h CRI; = 11). Intraoperative evaluations were performed before the start of surgery and administration of the treatments (T0); three minutes after the LD (T1); during incision and tissue divulsion (T2); during closure of the surgical wound (T3). Meloxicam (0.1 mg/kg) was administered at T3. Blood samples were collected for determination of plasma concentrations of fentanyl, lidocaine and ketamine. Pain scores and the number of postoperative analgesic rescues with morphine (0.5 mg/kg) were evaluated for 24 hours postoperatively using the short form of the Glasgow Composite Measure Pain Scale. Compared to T0, significant decreases in heart rate (from 84 ± 28 to 53 ± 16 bpm in the Fentanyl group and from 93 ± 16 to 63 ± 15 bpm in FLK) and mean arterial pressure (from 61 ± 5 to 49 ± 10 mmHg in Fentanyl and from 59 ± 3 to 38 ± 6 mmHg in FLK) were observed at T1. Arterial hypotension was transient, with normalization of values at T2 and T3. The expired fraction of isoflurane did not differ significantly between the groups. Plasma concentrations of fentanyl, lidocaine and ketamine remained within the therapeutic range. Postoperatively, the number of dogs requiring analgesic rescue was significantly lower in the FLK (0/11, 0%) than in the Fentanyl group (5/11, 45%). In dogs administered morphine and meloxicam as part of the anesthesia protocol, an intraoperative CRI of FLK abolished the requirement for postoperative analgesic rescue for 24 hours in dogs undergoing mastectomy.

Determination of the effective dosage of tiletamine-zolazepam-ketamine-xylazine, with or without methadone, in dogs.

OBJECTIVE: To determine the effective dosage of the combination tiletamine-zolazepam-ketamine-xylazine (TKX), with or without methadone, in dogs. STUDY DESIGN: Prospective, randomized, experimental study. ANIMALS: A total of 29 dogs. METHODS: Dogs were randomly administered TKX (group TKX, n = 13) or combined with 0.3 mg kg-1 of methadone (group TKXM, n = 16) intramuscularly. The TKX solution contained tiletamine (50 mg mL-1), zolazepam (50 mg mL-1), ketamine (80 mg mL-1) and xylazine (20 mg mL-1). The effective dosages for immobility in 50% and 95% of the population (ED50 and ED95) were estimated using the up-and-down method. Approximately 20 minutes after drug administration, a skin incision was performed and the response was judged as positive or negative if the dogs moved or did not move, respectively. The TKX volume for the subsequent dog in the same group was increased or decreased by 0.005 mL kg-1 if the response of the previous dog was positive or negative, respectively. Heart and respiratory rates, and sedation/anesthesia scores (range 0-21) were recorded before and 15 minutes after drug administration. RESULTS: Estimated ED50 and ED95 (95% confidence intervals) were: TKX, 0.025 (0.020-0.029) and 0.026 (0.010-0.042) mL kg-1; TKXM, 0.022 (0.018-0.025) and 0.033 (0.017-0.049) mL kg-1. Median (interquartile range) scores for sedation/anesthesia were 17 (16-18) and 17 (15-20), and times until lateral recumbency were 5 (4-6) and 6 (4-10) minutes in TKX and TKXM, respectively (p > 0.05). In both groups heart and respiratory rates decreased, but values remained acceptable for anesthetized dogs. CONCLUSIONS AND CLINICAL RELEVANCE: The results provide a guide for volumes of TKX and TKXM in dogs requiring restraint for minimally invasive procedures. Inclusion of methadone in the TKX combination did not influence ED50.

Evaluation of music therapy to reduce stress in hospitalized cats.

OBJECTIVES: This study aimed to evaluate the use of two different types of music - cat-specific music and classical music - compared with no music, to reduce stress in cats during hospitalization. METHODS: Thirty-five hospitalized cats were randomly divided into three groups and each group received a different stimulus - cat-specific music, classical music or no music (control) - throughout their hospitalization. Respiratory rate, salivary cortisol and social interaction were documented. A blinded researcher performed the Cat Stress Score (CSS) during the video analysis of recordings at five specific times over 31 h of hospitalization. RESULTS: There was no difference in the mean CSS between cats listening to cat-specific music, classical music and control throughout the five evaluations. Cat-specific music had a higher percentage of positive social interactions than the other groups on the first evaluation (P <0.05). The average respiratory rate was significantly lower in the classical music group vs control on the fourth evaluation (P <0.05). Although statistically insignificant, the average respiratory rate decreased only in the classical music group during the five evaluations. Cortisol quantification did not seem to follow the CSS results. However, owing to the low and unrepresentative number of samples, it was not possible to perform statistical analysis on these results or a group sample comparison. CONCLUSIONS AND RELEVANCE: Both cat-specific music and classical music seem to have some benefit to hospitalized cats. The salivary cortisol analysis was not adequate nor useful to measure stress in hospitalized cats in our study.

Epidural administration of combinations of ropivacaine, morphine and xylazine in bitches undergoing total unilateral mastectomy: a randomized clinical trial.

OBJECTIVE: To investigate the epidural administration of combinations of ropivacaine, morphine and xylazine in bitches undergoing unilateral mastectomy. STUDY DESIGN: Prospective, randomized, blinded, clinical study. ANIMALS: A total of 22 bitches scheduled to undergo unilateral mastectomy for mammary tumor excision. METHODS: Dogs were anesthetized with acepromazine (0.02 mg kg-1) and morphine (0.3 mg kg-1) intramuscularly, propofol intravenously (IV) and isoflurane. Prior to the beginning of surgery, dogs were randomly administered one of three epidural treatments: ropivacaine (0.75 mg kg-1) with morphine (0.1 mg kg-1) (group RM, n = 7); ropivacaine with xylazine (0.1 mg kg-1) (group RX, n = 8); or ropivacaine with morphine and xylazine (group RMX, n = 7). Cardiopulmonary variables and the expired concentration of isoflurane (Fe'Iso) were recorded intraoperatively. Meloxicam (0.1 mg kg-1) was administered IV during skin closure. Postoperative pain scores were evaluated with the Glasgow composite measure pain scale short form for 24 hours, and rescue analgesia with morphine (0.5 mg kg-1) was administered intramuscularly when pain scores were ≥ 6/24. RESULTS: Fe'Iso was significantly higher in group RM than in groups RX and RMX. Heart rate decreased significantly in groups RX and RMX, but blood pressure remained within acceptable values. The number of dogs administered rescue analgesia within 24 hours was significantly higher in group RX (seven dogs, 87.5%) than in groups RM (one dog, 14.3%; p = 0.01) and RMX (two dogs, 28.6%; p = 0.04). Time to standing was significantly longer in group RX than in group RM. CONCLUSIONS AND CLINICAL RELEVANCE: All epidural treatments provided adequate antinociception with minimal cardiovascular adverse effects during mastectomy. The inclusion of morphine (groups RM and RMX) provided the best postoperative analgesia. Owing to the undesirable effect of xylazine on ambulation, the combination ropivacaine-morphine appeared to provide greater benefits in bitches undergoing unilateral mastectomy.

Hemodynamic effects of incremental doses of acepromazine in isoflurane-anesthetized dogs.

OBJECTIVE: To evaluate the effects of incremental doses of acepromazine on hemodynamics in isoflurane-anesthetized dogs. STUDY DESIGN: Prospective, experimental study. ANIMALS: Healthy, adult, mixed-breed dogs (two male and four female) weighing 16.8 ± 5.1 kg (mean ± standard deviation). METHODS: Dogs were anesthetized with propofol (7 mg kg-1) intravenously (IV) and isoflurane. Thermodilution and arterial catheters were placed for hemodynamic monitoring and arterial blood sampling for blood gas analysis. Baseline measurements were performed with stable expired concentration of isoflurane (Fe'Iso) at 1.8%. Each dog was then administered four incremental acepromazine injections (10, 15, 25 and 50 µg kg-1) IV, and measurements were repeated 20 minutes after each acepromazine injection with Fe'Iso decreased to 1.2%. The four acepromazine injections resulted in cumulative doses of 10, 25, 50 and 100 µg kg-1 (time points ACP10, ACP25, ACP50 and ACP100, respectively). RESULTS: Compared with baseline, cardiac index (CI) increased significantly by 34%, whereas systemic vascular resistance index (SVRI) decreased by 25% at ACP50 and ACP100. Arterial oxygen content (CaO2) was significantly lower than baseline after all acepromazine injections (maximum decreases of 11%) and was lower at ACP50 and ACP100 than at ACP10. No significant change was found in heart rate, stroke index, oxygen delivery index and systolic, mean and diastolic blood pressures. Hypotension (mean arterial pressure < 60 mmHg) was observed in one dog at baseline, ACP10, ACP25 and ACP100, and in two dogs at ACP50. CONCLUSIONS AND CLINICAL RELEVANCE: Compared with isoflurane alone, anesthesia with acepromazine-isoflurane resulted in increased CI and decreased SVRI and CaO2 values. These effects were dose-related, being more pronounced at ACP50 and ACP100. Under the conditions of this study, acepromazine administration did not change blood pressure.

Sedative effects of acepromazine in combination with nalbuphine or butorphanol, intramuscularly or intravenously, in healthy cats: a randomized, blinded clinical trial.

OBJECTIVES: The aim of this study was to compare the sedative effects in cats administered acepromazine-nalbuphine and acepromazine-butorphanol, intramuscularly (IM) and intravenously (IV), and the occurrence of adverse cardiorespiratory effects. METHODS: Forty-six cats were randomly divided into four groups and administered acepromazine (0.05 mg/kg) combined with nalbuphine (0.5 mg/kg) or butorphanol (0.4 mg/kg), IV (ACP-NALIV and ACP-BUTIV groups, respectively) or IM (ACP-NALIM and ACP-BUTIM groups, respectively). Sedation scores, ease of intravenous catheter placement (simple descriptive scale [SDS] scores), physiologic variables, venous blood gases and the propofol dose required for anesthetic induction were recorded. RESULTS: Mild sedation was observed in all groups approximately 30 mins after treatment administration (timepoint T1, prior to propofol administration). Sedation scores at T1 increased above baseline in all groups (P <0.05), but no significant difference was observed among groups. Dynamic interactive visual analogue scale sedation scores (range 0-100 mm) recorded at T1 were (median [interquartile range]): ACP-NALIM, 12 (10-12); ACP-NALIV, 11 (6-16); ACP-BUTIM, 11 (7-14); and ACP-BUTIV, 12 (7-19). Overall, SDS scores did not change from baseline at T1 and there was no significant difference among groups. The propofol dose did not differ among groups. Blood gases remained within the reference intervals for cats. Significant decreases from baseline were detected for all groups in systolic arterial pressure (SAP). Mean ± SD values at T1 were (mmHg): ACP-NALIM, 108 ± 13; ACP-NALIV, 102 ± 10; ACP-BUTIM, 97 ± 13; and ACP-BUTIV, 98 ± 21. Arterial hypotension (SAP <90 mmHg) was recorded at T1 in 0/11, 1/13, 4/11 and 5/11 cats in groups ACP-NALIM, ACP-NALIV, ACP-BUTIM and ACP-BUTIV, respectively, and was further exacerbated after the induction of anesthesia with propofol. CONCLUSIONS AND RELEVANCE: In healthy cats administered acepromazine-nalbuphine and acepromazine-butorphanol, IM and IV, the degree of sedation was mild regardless of the protocol and the route of administration. The main adverse effect observed was a reduction in arterial blood pressure.

Hemodynamic, respiratory and sedative effects of progressively increasing doses of acepromazine in conscious dogs.

OBJECTIVE: To evaluate the effects of progressively increasing doses of acepromazine on cardiopulmonary variables and sedation in conscious dogs. STUDY DESIGN: Prospective, experimental study. ANIMALS: A group of six healthy, adult, mixed-breed dogs weighing 16.5 ± 5.0 kg (mean ± standard deviation). METHODS: Dogs were instrumented with thermodilution and arterial catheters for evaluation of hemodynamics and arterial blood gases. On a single occasion, acepromazine was administered intravenously to each dog at 10, 15, 25 and 50 µg kg-1 at 20 minute intervals, resulting in cumulative acepromazine doses of 10 µg kg-1 (ACP10), 25 µg kg-1 (ACP25), 50 µg kg-1 (ACP50) and 100 µg kg-1 (ACP100). Hemodynamic data and sedation scores were recorded before (baseline) and 20 minutes after each acepromazine dose. RESULTS: Compared with baseline, all acepromazine doses significantly decreased stroke index (SI), mean arterial pressure (MAP) and arterial oxygen content (CaO2) with maximum decreases of 16%, 17% and 21%, respectively. Cardiac index (CI) decreased by up to 19% but not significantly. Decreases of 26-38% were recorded for oxygen delivery index (DO2I), with significant differences for ACP50 and ACP100. Systemic vascular resistance index (SVRI) and heart rate did not change significantly. No significant difference was found among acepromazine doses for hemodynamic data. After ACP10, mild sedation was observed in five/six dogs and moderate sedation in one/six dogs, whereas after ACP25, ACP50 and ACP100, moderate sedation was observed in five/six or six/six dogs. CONCLUSIONS AND CLINICAL RELEVANCE: In conscious dogs, acepromazine decreased MAP, SI, CaO2 and DO2I, but no significant dose effect was detected. SVRI was not significantly changed, suggesting that the reduction in MAP resulted from decreased CI. The ACP25, ACP50 and ACP100 doses resulted in moderate sedation in most dogs; ACP10 resulted in only mild sedation.

Total intravenous anesthesia in domestic chicken (Gallus gallus domesticus) with propofol alone or in combination with methadone, nalbuphine or fentanyl for ulna osteotomy.

OBJECTIVE: To compare the propofol infusion rate and cardiopulmonary effects during total intravenous anesthesia with propofol alone and propofol combined with methadone, fentanyl or nalbuphine in domestic chickens undergoing ulna osteotomy. STUDY DESIGN: Prospective, randomized, experiment trial. ANIMALS: A total of 59 healthy Hissex Brown chickens weighing 1.5 ± 0.2 kg. METHODS: Anesthesia was induced with propofol (9 mg kg-1) administered intravenously (IV) and maintained with propofol (1.2 mg kg-1 minute-1) for 30 minutes. Birds were intubated and supplemented with 100% oxygen through a nonrebreathing circuit under spontaneous ventilation. Thereafter, each animal was randomly assigned to one of four groups: group P, no treatment; group PM, methadone (6 mg kg-1) intramuscularly (IM); group PN, nalbuphine IM (12.5 mg kg-1); and group PF, fentanyl IV (30 µg kg-1 loading dose, 30 µg kg-1 hour-1 constant rate infusion). During the osteotomy surgery, the propofol infusion rate was adjusted to avoid movement of birds and provide adequate anesthesia. Pulse rate, invasive blood pressure, respiratory frequency, end-tidal carbon dioxide partial pressure (Pe'CO2) and hemoglobin oxygen saturation (SpO2) were recorded. RESULTS: Data were available from 58 chickens. The mean ± standard deviation propofol infusion rate (mg kg-1 minute-1) for the duration of anesthesia was: group P, 0.81 ± 0.15; group PM, 0.66 ± 0.11; group PN, 0.60 ± 0.14; and group PF, 0.80 ± 0.07. Significant differences were P versus PM (p = 0.042), P versus PN (p = 0.002) and PF versus PN (p = 0.004). Pulse rate, blood pressure and SpO2 remained acceptable for anesthetized birds with minor differences among groups. Values of Pe'CO2 >60 mmHg (8 kPa) were observed in all groups. CONCLUSIONS AND CLINICAL RELEVANCE: Methadone and nalbuphine, but not fentanyl, decreased the propofol infusion rate required for anesthesia maintenance, but resulted in no obvious benefit in physiological variables.

Effects of 3 morphine doses, in combination with acepromazine, on sedation and some physiological parameters in dogs.

This study evaluated the effects of 3 morphine doses combined with acepromazine, on sedation and physiological parameters in 5 clinically healthy dogs. Four treatments were administered intramuscularly in a randomized, blinded, crossover design: acepromazine, 0.05 mg/kg, alone (ACP) and acepromazine plus morphine at doses of 0.25, 0.5, and 1.0 mg/kg body weight (BW) (AM0.25, AM0.5, and AM1.0, respectively). Sedation scores and cardiorespiratory variables were evaluated for 120 min after drug administration. The sedation scores were significantly higher with the AM0.25 and AM1.0 treatments than with the ACP treatment. At 30 min the scores were 36% to 66% higher with AM1.0 than with AM0.25 and AM0.5, respectively, but these differences were not significant. The physiological variables remained acceptable for dogs. The results of this study do not support the use of AM0.5 over AM0.25 to improve sedation in dogs, but they do indicate that sedation may be greater with AM1.0 than with AM0.25 and AM0.5. Studies with a greater number of samples are warranted to confirm this statement.

Cette étude visait à évaluer les effets de trois doses de morphine combinées à de l'acépromazine, sur la sédation et des paramètres physiologiques chez cinq chiens cliniquement en santé. Quatre traitements furent administrés par voie intramusculaire dans un design croisé randomisé à l'aveugle : acépromazine, 0,05 mg/kg seule (ACP) et acépromazine plus morphine à des doses de 0,25, 0,5, et 1,0 mg/kg de poids corporel (AM0,25, AM0,5, et AM1,0, respectivement). Les pointages de sédation et des variables cardiorespiratoires furent évalués pour 120 min après l'administration des drogues. Les pointages de sédation étaient significativement plus élevés avec les traitements AM0,25 et AM1,0 qu'avec le traitement ACP. À 30 min, les pointages étaient 36 % et 66 % plus élevés avec AM1,0 qu'avec AM0,25 et AM0,5, respectivement, mais ces différences n'étaient pas significatives. Les variables physiologiques sont demeurées acceptables pour les chiens. Les résultats de cette étude ne militent pas en faveur de l'utilisation d'AM0,5 par rapport à AM0,25 pour améliorer la sédation chez les chiens, mais ils indiquent que la sédation peut être plus grande avec AM1,0 qu'avec AM0,25 et AM0,5. Des études avec un plus grand nombre d'échantillons sont requises pour confirmer cet énoncé.(Traduit par Docteur Serge Messier).

Effects of three methadone doses combined with acepromazine on sedation and some cardiopulmonary variables in dogs.

OBJECTIVE: To evaluate the sedative and cardiopulmonary effects of three methadone doses, combined with acepromazine, in dogs. STUDY DESIGN: Prospective, randomized, complete block study. ANIMALS: Six healthy, adult, cross-bred dogs weighing 17.2±4.4 kg (mean±standard deviation). METHODS: Each dog was administered four treatments: acepromazine (0.05 mg kg-1) alone or acepromazine (same dose) in combination with methadone (0.25, 0.50 or 0.75 mg kg-1). All drugs were administered intramuscularly. Sedation was scored by a numeric descriptive scale (NDS, range 0-3) and a simple numerical scale (SNS, range 0-10). Heart rate, invasive blood pressure, arterial blood gases and rectal temperature were measured at 15 to 30 minute intervals for 120 minutes. RESULTS: According to NDS scores, mild to moderate sedation (NDS=1-2) was observed in most dogs in the acepromazine treatment, with only one out of six dogs scored as exhibiting intense sedation (NDS=3). All treatments with methadone resulted in significantly higher SNS scores compared with acepromazine alone. In these treatments, most dogs exhibited intense sedation (NDS=3). Increasing the dose of methadone from 0.25 to 0.50 or 0.75 mg kg-1 prolonged sedation in a dose-related manner, but did not influence the degree of sedation. The main adverse effects following administration of acepromazine-methadone treatments were decreased blood pressure, mild respiratory acidosis and decreased rectal temperature. These effects were well tolerated and resolved without treatment. CONCLUSIONS AND CLINICAL RELEVANCE: In this study in six dogs, acepromazine-methadone administration resulted in intense sedation in most dogs. The results are interpreted to indicate that a low dose of methadone (0.25 mg kg-1) administered in combination with acepromazine (0.05 mg kg-1) will induce short-term sedation in dogs, whereas higher doses of methadone should be administered when prolonged sedation is desired.

Tramadol does not enhance sedation induced by acepromazine in dogs.

The sedative effect of acepromazine combined with 2 doses of tramadol [3 and 5 mg/kg body weight (BW)] was compared with the sedative effect of acepromazine alone in dogs and the effects of each sedative protocol on cardiorespiratory variables were examined. This was a prospective, randomized, blinded, crossover study. Each of 6 dogs received 3 treatments at 1-week intervals. During all anesthetic episodes, dogs received 0.05 mg/kg BW acepromazine. Approximately 25 min later, dogs were given physiological saline (control) or tramadol [3 mg/kg BW (TR3) or 5 mg/kg BW (TR5)]. All drugs were administered intravenously. Variables evaluated included heart rate (HR), respiratory rate (RR), systolic, mean, and diastolic blood pressures (SAP, MAP, and DAP), and sedation [by use of a simple descriptive scale (SDS, range: 0 to 3) and a numeric rating scale (NRS, range: 0 to 10)]. Variables were recorded 25 min after acepromazine and for 80 min after saline or tramadol. Acepromazine administration resulted in mild sedation in most dogs and decreased RR, SAP, MAP, and DAP in all treatments. Tramadol administration did not significantly increase SDS or NRS scores compared to acepromazine alone. The only exception to this rule was observed at 20 min after TR3, when NRS was higher in this group than in the control treatment. Administration of tramadol (TR3 and TR5) decreased HR. Under the conditions of this study, sedation induced by acepromazine with tramadol was similar to that of acepromazine alone. The main adverse effects of the combination were a decrease in blood pressure and HR, without clinical significance.

L'effet sédatif de l'acépromazine combiné à deux doses de tramadol [3 et 5 mg/kg de poids corporel (PC)] a été comparé à l'effet sédatif de l'acépromazine seul chez des chiens et les effets de chaque protocole de sédation sur des variables cardio-respiratoires ont été examinés. Il s'agissait d'une étude prospective croisée, randomisée, réalisée à l'aveugle. Chacun des six chiens a reçu trois traitements à des intervalles de 1 semaine. Durant tous les épisodes anesthétiques, les chiens ont reçu 0,05 mg/kg PC d'acépromazine. Environ 25 min plus tard, les chiens ont reçu de la saline physiologique (témoin) ou du tramadol [3 mg/kg PC (TR3) ou 5 mg/kg PC (TR5)]. Toutes les drogues étaient administrées par voie intraveineuse. Les variables évaluées incluaient le rythme cardiaque (RC), le rythme respiratoire (RR), les pressions sanguines systolique, moyenne, et diastolique (PSS, PSM, et PSD), et la sédation [en utilisant une échelle descriptive simple (EDS, écart : 0 à 3) et une échelle de gradation numérique (EGN, écart : 0 à 10)]. Les variables ont été enregistrées 25 min après l'acépromazine et pendant 80 min après l'administration de saline ou de tramadol. L'administration d'acépromazine a résulté en une légère sédation chez la plupart des chiens et on nota une diminution de RR, PSS, PSM, et PSD avec tous les traitements. L'administration de tramadol ne fit pas augmenter de manière significative les pointages EDS et EGN lorsque comparée à l'acépromazine seul. La seule exception à cette règle a été observée à 20 min après TR3, alors que l'EGN était plus élevée dans ce groupe comparativement au témoin. L'administration de tramadol (TR3 et TR5) entraîna une diminution du RC. Dans les conditions de la présente étude, la sédation induite par l'acépromazine avec du tramadol était similaire à celle de l'acépromazine seul. Les principaux effets adverses de la combinaison étaient une diminution de la pression sanguine et du RC, mais sans signification clinique.(Traduit par Docteur Serge Messier).

Effects of a prolonged infusion of fentanyl, with or without atropine, on the minimum alveolar concentration of isoflurane in dogs.

OBJECTIVES: To evaluate the effect of a prolonged constant rate infusion (CRI) of fentanyl on the minimum alveolar concentration (MAC) of isoflurane (ISOMAC ) and to establish whether concurrent atropine administration influences ISOMAC in dogs. STUDY DESIGN: Prospective, crossover study. ANIMALS: Six healthy dogs weighing 13.0 ± 4.1 kg. METHODS: Dogs were anesthetized with isoflurane under conditions of normocapnia and normothermia. Arterial blood pressure was monitored invasively. Each dog was administered two treatments, on different occasions, in a crossover design. The dogs were administered intravenously (IV) an atropine bolus 0.02 mg kg(-1) and CRI at 0.04 mg kg(-1) hour(-1) (fentanyl-atropine treatment) or no atropine (fentanyl treatment). For each dog, baseline ISOMAC was measured in duplicate using a tail clamp technique. Subsequently, all dogs were administered a fentanyl bolus (5 µg kg(-1)) and CRI (9 µg kg(-1) hour(-1)) IV, and ISOMAC was re-determined at 120 and 300 minutes after initiation of the fentanyl CRI. RESULTS: Baseline ISOMAC values in the fentanyl and fentanyl-atropine treatments were 1.38 ± 0.16% and 1.39 ± 0.14%, respectively. Fentanyl significantly decreased the ISOMAC by 50 ± 9% and 47 ± 13% after 120 minutes and by 51 ± 14% and 50 ± 9% after 300 minutes (p < 0.001) in the fentanyl and fentanyl-atropine treatments, respectively. Compared with baseline, heart rate decreased significantly in the fentanyl treatment by 35% and 43% at 120 and 300 minutes, respectively. In the fentanyl-atropine treatment, heart rate did not change significantly over time. In both treatments, systolic arterial pressure increased from baseline after fentanyl. CONCLUSIONS AND CLINICAL RELEVANCE: In this study, fentanyl reduced the ISOMAC by approximately 50%. The ISOMAC remained stable throughout the 300 minute CRI of fentanyl, suggesting no cumulative effect of the opioid. Atropine did not influence ISOMAC in dogs.

Effects of acepromazine-morphine and acepromazine-methadone premedication on the minimum alveolar concentration of isoflurane in dogs.

OBJECTIVE: To evaluate the effects of premedication with acepromazine-morphine or acepromazine-methadone on the minimum alveolar concentration of isoflurane (ISOMAC) and the incidence of bradycardia and hypotension in dogs. STUDY DESIGN: Prospective randomized clinical study. ANIMALS: Thirty-two female dogs undergoing elective ovariohysterectomy. METHODS: Dogs were randomly assigned to one of three groups: no premedication (CONTROL group; n = 9); acepromazine (0.02 mg kg(-1)) and morphine (0.5 mg kg(-1)) (ACPMOR group; n = 11); and acepromazine (0.02 mg kg(-1)) and methadone (0.5 mg kg(-1)) (ACPMET group; n = 12). All drugs were administered intramuscularly. Twenty minutes later, anesthesia was induced with propofol administered intravenously to effect. Determinations of the ISOMAC were conducted by use of the up-and-down method using a quantal study design to determine the MAC for the population. Cardiovascular variables were registered immediately before noxious stimulation that was performed approximately 30 minutes after anesthetic induction. The occurrence of bradycardia (heart rates ≤ 70 beats minute(-1) in dogs ≤15 kg and ≤60 beats minute(-1) in dogs >15 kg) and hypotension (mean arterial pressure < 60 mmHg) were registered. RESULTS: The ISOMAC in CONTROL was 1.20 ± 0.11%. Compared with CONTROL, the ISOMAC was reduced by 33.3% and 68.3% in ACPMOR and ACPMET, respectively (p < 0.001). The ISOMAC was lower in ACPMET than in ACPMOR (p < 0.001). Bradycardia was observed in 0%, 45% and 50% of dogs and hypotension was observed in 56%, 55% and 67% of dogs in CONTROL, ACPMOR and ACPMET, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: The percentage reduction of the ISOMAC in ACPMET was approximately twice that in ACPMOR. Premedication with acepromazine-morphine or acepromazine-methadone increased the incidence of bradycardia. Hypotension was observed in most dogs during isoflurane anesthesia regardless of premedication.

Postoperative analgesic effects of epidural administration of neostigmine alone or in combination with morphine in dogs undergoing orthopedic surgery of the pelvic limbs.

OBJECTIVE: To evaluate the postoperative analgesic effects of epidural administration of morphine and neostigmine, either alone or in combination, in dogs. ANIMALS: 30 dogs undergoing orthopedic surgery on a pelvic limb. PROCEDURES: Anesthetic protocols were standardized. At the end of surgery, 10 dogs each received 1 of 3 epidural treatments: morphine (0.1 mg/kg), neostigmine (5 µg/kg), or morphine plus neostigmine (0.1 mg/kg and 5 µg/kg, respectively). Postoperative pain scores and the need for rescue analgesia were evaluated for 24 hours. RESULTS: Pain scores were higher in the neostigmine group, compared with scores for the morphine-neostigmine group, at 2 and 24 hours after surgery and higher in the morphine group than in the morphine-neostigmine group at 2 and 4 hours. During 24 hours, rescue analgesia was provided for 4, 7, and 2 of 10 dogs each in the morphine, neostigmine, and morphine-neostigmine groups, respectively. The number of dogs given rescue analgesia was significantly different among groups at 2, 3, 4, and 6 hours after surgery. Dogs in the morphine and morphine-neostigmine groups had a lower probability of receiving rescue analgesia within 24 hours than did dogs in the neostigmine group. CONCLUSIONS AND CLINICAL RELEVANCE: When administered epidurally, morphine alone or in combination with neostigmine provided effective postoperative analgesia in most dogs after orthopedic surgery, whereas neostigmine alone did not. Findings for this study suggested a potential role for neostigmine as an adjuvant for epidural analgesia in dogs undergoing orthopedic surgeries on the pelvic limbs.

Randomized clinical trial of the effects of a combination of acepromazine with morphine and midazolam on sedation, cardiovascular variables and the propofol dose requirements for induction of anesthesia in dogs.

The present study evaluated the effects of acepromazine combined with midazolam and morphine on sedation and cardiovascular variables as well as the propofol dose required for induction of anesthesia in dogs compared with acepromazine-morphine or midazolam-morphine. Dogs were randomly assigned to receive an intramuscular administration of (1) acepromazine (0.05 mg/kg) with 0.5mg/kg of morphine (group AM, n=10), (2) midazolam (0.5mg/kg) with 0.5mg/kg of morphine (group MM, n=9), or (3) acepromazine with midazolam and morphine at the same doses (group AMM, n=10). After 30 min, sedation was assessed by a numeric descriptive scale (NDS, range 0-3) and a simple numerical scale (SNS, range 0-10). Dogs were then administered IV propofol to allow endotracheal intubation. NDS and SNS scores were significantly higher in the AMM than in the MM group (P<0.05). There was a trend towards more dogs presenting with intense sedation (NDS=3) in AMM (6/10 dogs) compared with AM (1/10 dogs) and MM (1/9 dogs) (P=0.057). The propofol dose required for induction of anesthesia was significantly lower in AMM (4.0mg/kg) compared with MM (6.0mg/kg, P<0.01) but not AM (4.6 mg/kg). Heart rate decreased in AM after treatment and after intubation. Blood pressure decreased in groups AM and AMM following treatment and in all groups after intubation. The combination AMM resulted in intense sedation more frequently than AM and MM, and provided the greatest sparing effect in the propofol dose. Administration of AM and AMM but not MM decreased blood pressure although hypotension was not recorded in healthy dogs.

Effects of 8 hemodynamic conditions on direct blood pressure values obtained simultaneously from the carotid, femoral and dorsal pedal arteries in dogs.

OBJECTIVES: This study aimed to evaluate the effect of 8 hemodynamic conditions on blood pressure measurements taken from the carotid, femoral and dorsal pedal arteries of dogs. ANIMALS: Six healthy dogs. METHODS: During isoflurane anesthesia, catheters were introduced into the carotid, femoral and dorsal pedal arteries of dogs to allow simultaneous monitoring of direct blood pressure in each artery. The dogs were submitted to 8 hemodynamic conditions induced by combining changes in heart rate (bradycardia, normocardia, tachycardia) with changes in blood pressure (hypotension, normotension, hypertension). Values obtained from each arterial catheter were compared and agreement between central (carotid) and peripheral (femoral and dorsal pedal) values were analyzed by the Bland-Altman method. RESULTS: During hypotensive conditions, systolic arterial pressure (SAP) was lower in the femoral and dorsal pedal arteries compared to the carotid artery whereas during normotensive and hypertensive conditions, SAP was higher in peripheral arteries. During hypotensive states, increases in heart rate resulted in greater bias between central and peripheral SAP whereas during normotensive states, the bias decreased as heart rate increased. Mean and diastolic arterial pressures were lower in the femoral and dorsal pedal arteries than in the carotid artery during most hemodynamic conditions. CONCLUSIONS: In healthy anesthetized dogs, invasive blood pressure measurements in peripheral arteries may differ significantly from measurements in a central artery. The greatest differences were observed in SAP and the magnitude of differences between central and peripheral blood pressure measurements varied according to the dog's hemodynamic condition.

Effects of tramadol alone, in combination with meloxicam or dipyrone, on postoperative pain and the analgesic requirement in dogs undergoing unilateral mastectomy with or without ovariohysterectomy.

OBJECTIVE: To compare the effects of tramadol alone, or in combination with dipyrone or meloxicam, on postoperative pain and analgesia requirement after unilateral mastectomy with or without ovariohysterectomy in dogs. STUDY DESIGN: Prospective, randomized, clinical study. ANIMALS: Twenty seven bitches undergoing unilateral mastectomy with or without ovariohysterectomy. METHODS: Anesthesia was induced with propofol and maintained with isoflurane and a constant rate infusion of morphine. Before the end of surgery, dogs were randomly assigned to receive intravenous tramadol alone (3 mg kg(-1), group T), combined with dipyrone (30 mg kg(-1), group TD) or meloxicam (0.2 mg kg(-1), group TM). Dogs received additional doses of tramadol (groups T and TM) or tramadol with dipyrone (group TD) at 8 and 16 hours after extubation. Postoperative pain was assessed by a blinded observer before anesthesia (baseline) and at 1, 2, 3, 4, 6, 8, 12, 16 and 24 hours after extubation using a visual analog scale (VAS) and a modified Glasgow scale. Rescue analgesia (morphine, 0.5 mg kg(-1)) was administered if the Glasgow pain score was >3.5. RESULTS: There were no significant differences among groups in pain scores evaluated by the VAS or the Glasgow scale. In groups T, TD and TM, pain scores were significantly higher than at baseline for 6, 8 and 2 hours, respectively. Rescue analgesia was administered to 3/9, 2/9 and 1/9 dogs in groups T, TD and TM, respectively (p > 0.05) [Correction added on 15 August 2013, after first online publication: 'T, TM and TD' was changed to 'T, TD and TM'.]. CONCLUSIONS AND CLINICAL RELEVANCE: Under the conditions of this study, tramadol alone or in combination with dypyrone or meloxicam provided effective analgesia for 24 hours in most dogs after unilateral mastectomy with or without ovariohysterectomy. Further evaluation of combination therapies is needed in larger groups of dogs.

Assessment of postoperative pain after unilateral mastectomy using two different surgical techniques in dogs.

BACKGROUND: There are few studies reporting pain and postoperative analgesia associated with mastectomy in dogs. The aim of this study was to evaluate postoperative pain after unilateral mastectomy using two different surgical techniques in the dog. FINDINGS: Twenty female dogs were assigned (n=10/group) to undergo unilateral mastectomy using either the combination of sharp and blunt dissection (SBD) or the modified SBD (mSBD) technique, in which the mammary chain is separated from the abdominal wall entirely by blunt (hand and finger) dissection except for a small area cranial to the first gland, in a prospective, randomized, clinical trial. All dogs were premedicated with intramuscular acepromazine (0.05 mg/kg) and morphine (0.3 mg/kg). Anesthesia was induced with intravenous ketamine (5 mg/kg) and diazepam (0.25 mg/kg), and maintained with isoflurane. Subcutaneous meloxicam (0.2 mg/kg) was administered before surgery. Postoperative pain was evaluated according to the University of Melbourne pain scale (UMPS) by an observer who was blinded to the surgical technique.. Rescue analgesia was provided by the administration of intramuscular morphine (0.5 mg/kg) if pain scores were >14 according to the UMPS. Data were analyzed using t-tests and ANOVA (P>0.05). There were no significant differences between the groups for age, weight, extubation time, and duration of surgery and anesthesia (P>0.05). There were no significant differences for postoperative pain scores between groups. Rescue analgesia was required in one dog in each group. CONCLUSIONS: The two surgical techniques produced similar surgical times, incidence of perioperative complications and postoperative pain. Multimodal analgesia is recommended for treatment of postoperative pain in dogs undergoing unilateral mastectomy.