Sedative and cardiorespiratory effects of dexmedetomidine alone or combined with acepromazine in healthy cats.

The purpose of this study was to assess sedation, emesis and cardiovascular effects of dexmedetomidine alone or combined with acepromazine in healthy cats. Fourteen male cats aged 0.9 ± 0.5 years and weighing 3.7 ± 0.7 kg were randomly assigned to one of two experimental groups: GD, dexmedetomidine 5 µg/kg; and GDA, dexmedetomidine 5 µg/kg with acepromazine 0.03 mg/kg, all intramuscularly. Measurements were recorded at baseline, at 20 minutes and then at 10-minute intervals following sedation and included heart rate (HR), respiratory rate (FR), systolic arterial pressure (SAP), rectal temperature (RT), number of episodes of emesis and sedation score (0-4). Data were compared using ANOVA for repeated measures followed by Sídák and Dunnet test. Sedation scores were compared between groups at T20 using Mann-Whitney test. Significance was considered when P <0.05. At T20, HR was significantly lower in GDA (99 ± 14 beats/min) compared with GD (133 ± 19 beats/min) and SAP was significantly lower in both groups compared with baseline (126 ± 14 vs. 148 ± 26 and 111 ± 13 vs. 144 ± 17 mmHg in GD and GDA, respectively). Duration of sedation was similar between groups, although sedation scores differed significantly at T20, with 1 (0-4) in GD and 4 (4-4) in GDA. More episodes of emesis were recorded in GD compared with GDA. The combination of dexmedetomidine and acepromazine produced more profound sedation with faster onset and lower incidence of emesis compared with dexmedetomidine alone in healthy cats.

Cardiorespiratory/sedative effects of a peptide identified in crotalic venom compared to acepromazine and xylazine in horses

The purpose of this study was to investigate whether intravenous crotalphine produces significant sedation, as well as physiological changes, in healthy standing horses. Six mares, aged 8 years and weighing 415kg underwent three different treatments in a crossover design: TA (acepromazine: 50μg.kg-1), TC (crotalphine: 0.01μg.kg-1) and TX (xylazine: 1000μg.kg-1), intravenously. At various time points over 60 minutes, physiologic variables were recorded: heart rate, respiratory rate, and rectal temperature. The head height from the ground (HHG) was evaluated in centimeters. Data were analyzed using ANOVA followed by Dunnett’s test or Friedman followed by Dunn’s test, under 5% significance. Heart rate decreased significantly at M5 and M10 compared with Mb in TX (28±7, 26±6 and 40±8 beats/minute-1, respectively; p=0.0004). Respiratory rate and rectal temperature did not differ among groups or time points. The HHG significantly decreased in all groups compared with Mb at various time points (p<0.0001). In conclusion, crotalphine did not produce reliable and durable sedation in healthy standing mares and did not influence cardiorespiratory variables in a clinically relevant manner.

O objetivo deste estudo foi investigar se a administração de crotalfina intravenosa produz sedação significativa e alterações fisiológicas em equinos saudáveis. Seis éguas, idade média de oito anos e peso médio de 415kg, foram submetidas a três tratamentos distintos: TA (acepromazina: 50μg/kg), TC (crotalfina: 0,01μg/kg) e TX xilazina: 1000μg/kg), por via intravenosa. Em vários momentos, ao de longo de 60 minutos, as variáveis fisiológicas registradas foram frequência cardíaca, frequência respiratória e temperatura retal. A altura de cabeça ao solo (ACS) foi avaliada em centímetros. Os dados foram analisados pela ANOVA, seguida pelo teste de Dunnett ou de Friedman e, depois, pelo teste de Dunn, sob 5% de significância. A frequência cardíaca diminuiu significativamente em M5 e M10 em comparação com Mb em TX (28±7, 26±6 e 40±8 bpm, respectivamente; P=0,0004). A frequência respiratória e a temperatura retal não diferiram entre os grupos ou os pontos de tempo. O HHG diminuiu significativamente em todos os grupos em comparação com Mb em vários momentos (P <0,0001). Em conclusão, a crotalfina não produziu sedação confiável e durável em éguas saudáveis e não influenciou as variáveis cardiorrespiratórias de maneira clinicamente relevante.

Comparison of Coinduction Adjuvants to Propofol in Healthy Cats Sedated With Dexmedetomidine.

This study aimed to compare the effects of different coinduction agents on the duration and dose of propofol in healthy cats. Six cats aged 4.8 ± 1.0 years and weighing 4.4 ± 1.1 kg participated in 4 treatment groups of propofol combined with: saline or control group (TC); ketamine 2 mg/kg (Tket); fentanyl 1 µg/kg (Tfen); or midazolam 0.3 mg/kg (Tmid). Twenty minutes following premedication with dexmedetomidine at 10 µg/kg, induction followed the same protocol in all groups, starting with a propofol bolus of 1 mg/kg over 1 minute followed by an adjuvant, then propofol again at 1 mg/kg/minute for orotracheal intubation. Variables recorded were (in minutes): time of extubation, time to return of palpebral reflex, eye recentralization, recovery of consciousness, quadrupedal position and total propofol dose used (mg/kg). A comparison between the 4 groups was performed by analysis of variance followed by Dunnett test under 5% significance. There was no significant difference in any of the times evaluated during anesthetic recovery between the groups. The propofol dose used to allow orotracheal intubation was significantly lower in all groups compared to TC (P < .05). Ketamine, midazolam, and fentanyl are indicated as suitable choices for coinduction with propofol in cats.

Comparison of two volumes for sciatic perineural injection using 1% methylene blue in rabbit cadavers / [Comparação de dois volumes para injeção perineural no nervo isquiático utilizando azul de metileno 1% em cadáveres de coelhos]

The purpose of this study was to assess the efficacy of a blind technique for sciatic and femoral nerve block in rabbit cadavers by evaluating the spread of 1% methylene blue at two different volumes. Nine recently euthanized rabbits weighing 2.5(0.3kg were used. The sciatic (SN) and femoral (FN) nerves of each limb were randomly assigned for injection with 1% methylene blue at 0.2mL/kg (G0.2) or 0.3mL/kg (G0.3). Nerves were dissected and measured for depth and extension of staining (cm). Mean comparisons were performed using paired t test. The relation between volume and nerve staining ( 2cm was assessed using chi-square test. The mean depth of SN was 1.9±0.2 and 1.6±0.3cm and staining 1.9±1.4 and 2.0±1.2cm, respectively in G0.2 and G0.3. No relation was found between depth and dye spread and there was no association between nerve staining ( 2.0cm and volume of solution. The FN failed to be stained in all subjects. In conclusion, SN injection can be successfully performed without guidance in rabbits. The lower volume (0.2mL/kg) is recommended to avoid systemic toxicity.(AU)

O objetivo deste estudo foi avaliar a eficácia de uma técnica para bloqueio às cegas dos nervos isquiático e femoral em cadáveres de coelhos, por meio da avaliação da dispersão de azul de metileno 1% em dois volumes distintos. Nove coelhos recém-eutanasiados, com peso 2,5(0,3kg, foram utilizados. Os nervos isquiático (NI) e femoral (NF) de cada membro foram aleatoriamente designados para injeção com azul de metileno 1% a 0,2mL/kg (G0,2) ou 0,3mL/kg (G0,3). Em seguida, foram dissecados e mensurados em relação à sua profundidade e extensão corada (cm). As médias foram comparadas por meio de teste t pareado. A relação entre volume e extensão corada ( 2cm foi avaliada utilizando-se teste de qui-quadrado. A profundidade média do NI foi 1,9±0,2 e 1,6±0,3cm, e a extensão corada 1,9±1,4 e 2,0±1,2cm, respectivamente, no G0,2 e no G0,3. Não houve relação entre a profundidade e a extensão corada ou entre a extensão corada ( 2,0cm e o volume de solução. Não foi observada coloração do NF em nenhum cadáver. Concluiu-se que a injeção do NI pode ser realizada com sucesso sem auxílio de tecnologias em coelhos. O menor volume (0,2mL/kg) é recomendado para evitar toxicidade sistêmica.(AU)

Propofol at Single Bolus and Continuous Rate Infusion Significantly Increases Serum Triglycerides, but not Cholesterol, In Healthy Bitches Undergoing Elective Ovariohysterectomy.

This study aimed to investigate the effects of a single bolus and continuous rate infusion (CRI) of 1% propofol on cholesterol and triglyceride levels of healthy bitches undergoing elective ovariohysterectomy. 10 healthy bitches undergoing elective ovariohysterectomy had blood samples obtained at baseline (TB), 15 minutes following premedication with acepromazine and morphine (TPM), after an intravenous bolus of propofol (induction to anesthesia, TIND) and following 90 minutes of CRI of propofol started at 0.4 mg kg-1 min-1 and adjusted according to individual requirements (TCRI). Data were initially tested for normality using the Shapiro-Wilk test, and comparisons were performed using Friedman followed by Dunn post-hoc test. Serum cholesterol levels significantly decreased at TIND and TCRI (median [min-max] 201 mg dL-1 [111-234 mg dL-1], and 215 mg dL-1 [111-239 mg dL-1]), respectively, compared with TB (232 [128-245 mg dL-1]) and TPM (206 [115-255 mg dL-1]). No differences were found between TIND and TCRI. Triglyceride levels increased significantly at TIND (120 [67-231 mg dL-1]) and TCRI (229 [73-549 mg dL-1]) compared with TPM (36 [51-29 mg dL-1]), and TCRI compared with TB. In conclusion, 1% propofol lipid emulsion significantly increases serum triglycerides and causes lipemia in healthy dogs at a single bolus or CRI.

Lidocaine administered at a continuous rate infusion does not impair left ventricular systolic and diastolic function of healthy rabbits sedated with midazolam.

Lidocaine is a versatile drug that not only provides local anesthesia, but also reduces anesthetic requirements of other agents and has antiarrhythmic, pro-kinetic, anti-inflammatory, antiendotoxemic and antioxidant effects. As it is a drug commonly used in critically ill patients, its safety from the cardiovascular system should be ensured. The aim of this study was to determine the effects of a continuous rate infusion (CRI) of lidocaine on left ventricular systolic and diastolic function of healthy rabbits sedated with midazolam by use of transthoracic echocardiography. Ten New Zealand healthy rabbits were sedated with intramuscular midazolam (1 mg/kg) and enrolled in two experimental treatments (control or lidocaine). The control treatment (CT) comprised an intravenous bolus of 0.9% sodium chloride (0.05 mL/kg) followed by CRI at 5 mL/h, whereas the lidocaine treatment (LT) comprised a bolus of 2% lidocaine without epinephrine at 1 mg/kg followed by CRI at 50 µg/kg/minute. Echocardiographic and hemodynamic variables were studied. Variables were recorded at baseline (TB) and 20, 40 and 60 minutes following start of CRI (T20, T40 and T60, respectively). No differences were found between treatments. The results of this study demonstrate that a continuous rate infusion of lidocaine at 50 µg/kg/minute does not impair echocardiographic indices of left ventricular systolic and diastolic function of healthy rabbits sedated with midazolam.

Different rates of tramadol infusion for peri and postoperative analgesia in dogs undergoing orthopedic surgery / Comparação de diferentes taxas de infusão de tramadol para analgesia peri e pós-operatória em cães submetidos a procedimentos cirúrgicos ortopédicos sob anestesia geral inalatória

The study aimed to determine the continuous rate infusion of tramadol associated with peri- and postoperative analgesia for orthopedic surgeries in dogs, as well as cardiorespiratory and adverse effects. Thirty dogs aged 4.2±1.2 years and weighing 15.1±0.9kg were enrolled in the study, premedicated intramuscularly with acepromazine (0.04mg kg-1) and tramadol (2mg kg-1); anesthesia was induced with propofol and maintained with isoflurane in oxygen. Three infusion rates were compared, comprising three experimental groups: G2: 2.0mg kg-1 h-1; G2.5: 2.5mg kg-1 h-1; and G3: 3.0mg kg-1 h-1. Surgery was initiated 15 minutes following the start of tramadol infusion. During anesthesia, animals were monitored in predefined time points: immediately after tracheal intubation and start of inhalation anesthesia (T0); surgical incision (TSI); final suture (TFS) and end of tramadol infusion (TEI), which was maintained for at least 120 minutes and prolonged according to the duration of surgery. Postoperative analgesia was evaluated through an interval pain scoring scale and the Melbourne pain scale. The mean time of tramadol infusion was greater than 120 minutes in all groups and no differences were found among them (141±27 minutes in G2, 137±27 minutes in G2.5 and 137±30 minutes in G3). Perioperative analgesia was regarded as short and did not correlate with infusion rates. Tramadol infusion provided adequate analgesia with cardiorespiratory stability Analgesia was not dose-dependent, however, and residual postoperative effects were short-lasting, which warrants proper postoperative analgesia following tramadol infusion. Additional studies are required using higher infusion rates and standardized nociceptive stimulation in order to determine how doses influence tramadol analgesia and whe therthereis a limit to its effect in dogs.(AU)

Objetivou-se determinar a infusão de taxa contínua de tramadol associada à analgesia peri e pós-operatória para cirurgias ortopédicas em cães, além de efeitos cardiorrespiratórios e adversos. Foram utilizados 30 cães, com idade média de 4,2±1,2 anos e pesos médios de 15,1±0,9kg, pré-medicados por via intramuscular com acepromazina (0,04mg/kg) e tramadol (2mg/kg). A anestesia foi induzida com propofol e mantida com isoflurano em oxigênio. Foram comparadas três taxas de infusão, compreendendo três grupos experimentais: G2: 2,0mg/kg; G2,5: 2,5mg/kg1; e G3: 3,0mg/kg. A cirurgia começou 15 minutos após o início da infusão de tramadol. Durante a anestesia, os animais foram monitorados nos seguintes momentos: imediatamente após a intubação traqueal e o início da anestesia inalatória (T0); incisão cirúrgica (TSI); final de sutura (TFS) e final da infusão de tramadol (TEI), que foi mantida por, pelo menos, 120 minutos e prolongada de acordo com a duração da cirurgia. A analgesia pós-operatória foi avaliada por escalas de pontuação de dor, conforme a escala intervalar de avaliação de dor e a escala de contagem variável de avaliação de dor da Universidade de Melbourne, a cada uma hora. O tempo médio de infusão de tramadol foi maior que 120 minutos em todos os grupos, e não foram encontradas diferenças entre elas (141±27 minutos em G2, 137±27 minutos em G2,5 e 137±30 minutos em G3). A analgesia perioperatória foi adequada na maioria dos indivíduos e a pós-operatória foi considerada curta, não correlacionada àquelas com diferentes taxas de infusão. A infusão de tramadol nas taxas estudadas produziu analgesia adequada com estabilidade cardiorrespiratória. A analgesia não foi dose dependente, no entanto os efeitos residuais pós-operatórios foram considerados curtos, o que determina a necessidade de analgesia adequada após infusão contínua de tramadol. Estudos adicionais que utilizam taxas mais elevadas de infusão de tramadol e estimulação nociceptiva padrão são necessários para determinar em que medida as doses influenciam a analgesia de tramadol e se há um limite nos seus efeitos nos cães.(AU)

Anestesia local por tumescência com lidocaína em cadelas submetidas a mastectomia / Tumescent local anesthesia with lidocaine in dogs undergoing mastectomy

O presente estudo investigou os benefícios da anestesia por tumescência com lidocaína em cadelas submetidas à mastectomia, visando ao conforto do paciente e à sua recuperação pós-operatória. Foram utilizados sete animais, de peso e raças variadas, que apresentavam neoplasia em região de cadeia mamária e que foram submetidos à cirurgia de mastectomia. Todos os animais receberam o mesmo protocolo anestésico, sendo utilizado como MPA a associação entre acepromazina e morfina, nas doses de 0,04mg/kg e 0,4mg/kg (IM), respectivamente. Após 15 minutos, foi alocado um cateter em veia cefálica e realizou-se a indução com propofol 4mg/kg e midazolam 0,2mg/kg, seguida de manutenção anestésica com isofluorano. Posteriormente à instrumentação, procedeu-se à técnica de anestesia por tumescência com solução gelada composta por ringer lactato, lidocaína 2% sem vasoconstritor e adrenalina, em um volume total de 15mL/kg. Em média, o tempo de duração do procedimento foi de 74±18 minutos. O pico plasmático de lidocaína deu-se entre 30 e 60 minutos após a infiltração da solução. O resgate analgésico foi realizado após sete horas, aproximadamente, da infiltração. Pode-se concluir que a anestesia por tumescência com lidocaína deve ser considerada como constituinte do protocolo anestésico e analgésico de cadelas a serem submetidas à cirurgia de mastectomia, proporcionando estabilidade de parâmetros, segurança e recuperação pós-operatória de boa qualidade.

The present study investigated the benefits of tumescent anesthesia with lidocaine in dogs undergoing mastectomy, seeking the patients' comfort and their postoperative recovery. Seven animals, with different weight and breed, who had cancer in the region of mammary chain underwent mastectomy surgery. All animals received the same anesthetic protocol being used as the association between acepromazine and morphine doses of 0.04mg.kg-1 and 0.4mg.kg-1 (IM), respectively. After 15 minutes a catheter was placed in the cephalic vein and induction with propofol 4mg.kg-1 and 0.2mg.kg-1 followed by maintenance with isoflurane anesthesia was done. After instrumentation, we proceeded to the tumescent anesthesia technique with ice-cold solution consisting of Ringer's lactate, lidocaine 2% without epinephrine and adrenaline in a total volume of 15mL.kg-1. The average duration of the procedure was 74±18 minutes. The plasmatic peak of lidocaine was between 30 and 60 minutes after infiltration. The rescue analgesic was performed after approximately seven hours of infiltration. It can be concluded that the tumescent anesthesia with lidocaine should be considered as a constituent of anesthetic and analgesic protocol in dogs undergoing mastectomy surgery providing parameter stability, safety and good quality postoperative recovery.