Sedative effects of dexmedetomidine, dexmedetomidine–pethidine and dexmedetomidine–butorphanol in cats L. NAGORE C. SOLER L. GIL I. SERRA G. SOLER & J. I. REDONDO Departamento de Medicina y Cirugı ´a Animal, Facultad de Veterinaria, Instituto de Ciencias Biome ´dicas, Universidad CEU Cardenal Herrera, Valencia, Espan ˜a Nagore, L., Soler, C., Gil, L., Serra, I., Soler, G., Redondo, J. I. Sedative effects of dexmedetomidine, dexmedetomidine–pethidine and dexmedetomidine–butorph- anol in cats. J. vet. Pharmacol. Therap. doi: 10.1111/j.1365-2885.2012. 01405.x. The purpose of this study was to assess the clinical effects of dexmedetomidine, both alone and combined with pethidine or butorphanol, in cats. A prospective randomized blind study was performed. Thirty cats were randomly assigned to three groups of 10 animals: D: dexmedetomidine (20 lg ⁄ kg IM); DP: dexmedetomidine (10 lg ⁄ kg IM) and pethidine (2.5 mg ⁄ kg IM); DB: dexmede- tomidine (10 lg ⁄ kg IM) and butorphanol (0.4 mg ⁄ kg IM). Quality of sedation, analgesia, muscle relaxation and the possibility of performing some clinical procedures were compared using a multifactorial scale. Sedation, analgesia and muscle relaxation increased progressively over time and did not differ in the three protocols. The three protocols facilitated the completion of several clinical procedures. The clinical variables studied showed a similar behaviour in the three protocols and remained close to the baseline, except for a drop in heart rate in protocol D. In conclusion, dexmedetomidine, either alone or combined with pethidine or butorphanol, offers suitable sedation, analgesia and relaxation to perform various clinical procedures in cats. (Paper received 2 November 2011; accepted for publication 9 April 2012) Jose ´ I. Redondo, Departamento de Medicina y Cirugı ´a Animal, Facultad de Veterinaria, Instituto de Ciencias Biome ´dicas, Universidad CEU Cardenal Herrera, Avd. Seminario s ⁄ n., Moncada, Valencia, Espan ˜a. E-mail: nacho@uch.ceu.es INTRODUCTION Alpha 2 adrenergic agonists are a group of widely used sedatives in feline medicine. They provide deep sedation, analgesia and muscle relaxation. The other benefit is that the anaesthesiologist may have the ability to antagonize sedation with the use of a specific antagonist (atipamezole) at the end of the procedure or in the event of emergency. However, they also have important side effects, such as bradycardia, decreased cardiac output, increased peripheral vascular resistance, respiratory depression and vom- iting (Sinclair, 2003). Medetomidine is a commonly used a 2 agonist sedative. It is a racemic mixture of two stereoisomers: dexmedetomidine and levomedetomidine. Dexmedetomidine is the enantiomer, which has sedative effects. Levomedetomidine has no effect on cardio- vascular parameters and causes no apparent sedation or analgesia (Kuusela et al., 2000). Recently, the European Med- icines Agency (EMEA) has authorized the marketing of dex- medetomidine within the European Union as a sedative in dogs and cats (EMEA, 2009). Several studies have demonstrated the efficacy of sedation with dexmedetomidine in cats (Ansah et al., 1998; Mendes et al., 2003; Granholm et al., 2006; Slingsby & Taylor, 2008). However, the cardiovascular and respiratory effects of a 2 agonists are dose dependent (Sinclair, 2003); thus, the lowest effective dose should be used. Typical label sedative doses of medetomidine in cats are 10–40 lg ⁄ kg IV and 40–80 lg ⁄ kg IM (Sinclair, 2003). A study has demonstrated that there is a 1:2 dose equivalence between dexmedetomidine and medetomidine (Ans- ah et al., 1998). On the other hand, alpha 2 agonists are often combined with opioids in the clinical practice. Many veterinary procedures requiring sedation are painful and require analgesia. Alpha 2 agonists are analgesic, but the duration of the analgesia may be short (Slingsby et al., 2010). Opioid ⁄ alpha 2 agonist combinations provide good sedation and analgesia (Selmi et al., 2003; Slingsby et al., 2010). These effects may be achieved at much lower doses of the alpha 2 agonist because of additive or synergistic effects of the two agents (Ossipov et al., 1990). The objective of this paper was to assess in cats whether the sedative ⁄ analgesic ⁄ clinical value of sedation with dexmedetom- idine ⁄ opioid would be different when compared to dexmedetom- idine alone if the dexmedetomidine dose was reduced and an opioid was added. In other words, our hypothesis was that the use of dexmedetomidine–butorphanol or dexmedetomidine– pethidine would result in grater sedation and analgesia than dexmedetomidine alone. J. vet. Pharmacol. Therap. doi: 10.1111/j.1365-2885.2012.01405.x Ó 2012 Blackwell Publishing Ltd 1