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BackgroundHandling of common marmoset (Callithrix jacchus) usually requires chemical restraint. Ketamine has been associated with muscle damage in primates, while common marmosets, compared to other primates, additionally display an exceptional high sensitivity to ketamine-associated side-effects. Notably, muscle twitching movements of limbs and hands, and a marked increase in salivation are observed. We investigated two alternative intramuscular (i.m.) immobilisation protocols against ketamine (50 mg/kg; protocol 1) in a double-blind randomised crossover study in ten healthy adult common marmosets for use as a safe reliable, short-term immobilisation and sedation. These protocols comprised: alphaxalone (12 mg/kg; protocol 2) and 25 mg/kg ketamine combined with 0.50 mg/kg medetomidine (reversal with 2.5 mg/kg atipamezole; protocol 3A). Following completion and unblinding, the project was extended with an additional protocol (3B), comprising 25 mg/kg ketamine combined with 0.05 mg/kg medetomidine (reversal with 0.25 mg/kg atipamezole, twice with 35 min interval).ResultsAll protocols in this study provided rapid onset (induction times <5 min) of immobilisation and sedation. Duration of immobilisation was 31.23 ± 22.39 min, 53.72 ± 13.08 min, 19.73 ± 5.74 min, and 22.78 ± 22.37 min for protocol 1, 2, 3A, and 3B, respectively. Recovery times were 135.84 ± 39.19 min, 55.79 ± 11.02 min, 405.46 ± 29.81 min, and 291.91 ± 80.34 min, respectively. Regarding the quality, and reliability (judged by pedal withdrawal reflex, palpebral reflex and muscle tension) of all protocols, protocol 2 was the most optimal. Monitored vital parameters were within clinically acceptable limits during all protocols and there were no fatalities. Indication of muscle damage as assessed by AST, LDH and CK values was most prominent elevated in protocol 1, 3A, and 3B.ConclusionsWe conclude that intramuscular administration of 12 mg/kg alphaxalone to common marmosets is preferred over other protocols studied. Protocol 2 resulted in at least comparable immobilisation quality with acceptable and less frequent side effects and superior recovery quality. In all protocols, supportive therapy, such as external heat support, remains mandatory. Notably, an unacceptable long recovery period in both ketamine/medetomidine protocols (subsequently reversed with atipamezole) was observed, showing that α-2 adrenoreceptor agonists in the used dose and dosing regime is not the first choice for sedation in common marmosets in a standard research setting.

Animals considered to be painful received rescue analgesia and were allocated to a post-rescue protocol; animals which were unresponsive to rescue analgesia were removed from the study. Data were analysed with anova, two-sample t-tests or Chi-square tests. Time to intervention was analysed with Kaplan-Meier methodology. RESULTS: Forty dogs were enrolled. Twenty dogs (9 DMED and 11 MOR) did not require rescue analgesia. Eleven DMED and eight MOR dogs were allocated to the postrescue protocol and seven of these removed from the study. Significant differences in pain scores between groups were not observed during the first 12 hours, however, DMED dogs were less (p = 0.009) painful during the last 12 hours. Sedation score over the entire 24-hour study was not significantly different between groups. CONCLUSION / CLINICAL RELEVANCE: Dexmedetomidine CRI was equally effective as MOR CRI at providing postoperative analgesia and no clinically significant adverse reactions were noted. This study shows the potential of DMED to contribute to a balanced postoperative analgesia regimen in dogs. PMID: 19470144 [PubMed -indexed for MEDLINE]

Buprenorphine is commonly used as ( part of ) postoperative analgesic treatment with dosage dependent side-effects such as pica behaviour. No strict consensus exists about the optimal dosing interval of buprenorphine, as its duration of action has been described as being in the range of 6 -12 h. In this study, dosing intervals of 8 h (thrice-a-day) and 12 h (twice-a-day) for buprenorphine in a multimodal analgesic strategy (concurrent administration of a non-steroidal anti-inflammatory drug) were compared on food intake, weight and side-effects (gnawing on plastic Petri dishes and growth rate, indicative of pica behaviour) in rats. The food intake and weight of both intervals were comparable, as the animals from the twice-a-day group did not lose more weight or consumed less food during the analgesic period. The rats from the thrice-a-day group suffered from more side-effects, as the growth rate was decreased and more plastic was gnawed on. It is recommended to carefully evaluate analgesic and side-effects when using buprenorphine. When side-effects are observed, the possibility of increasing the dosing interval of buprenorphine should be explored. In this study, increasing the dosing interval of buprenorphine in a multimodal analgesic regimen resulted in reduced unwanted side-effects, without increasing weight loss or decreasing food intake. Although this is suggestive of provision of comparable analgesia, future studies including more pain-related readout parameters to assess the effect of the dosing interval on analgesic efficacy are recommended.