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ABSTRACT:The goal of this study was to establish an easy-to-perform, reliable, and safe protocol for intraperitoneal injection anaesthesia in rats, as well as an easy method to assess anaesthesia depth under routine clinical conditions. Seventy Wistar rats (35 males and 35 females) were used to evaluate intraperitoneal anaesthesia with ketamine (75 mg/kg) combined with one of the following central nervous system depressors: acepromazine (2.5 mg/kg), diazepam (5 mg/kg), medetomidine (0.5 mg/kg), midazolam (5 mg/kg) and xylazine (2.5 mg/kg). Significant differences were found between the combinations in ataxia, recovery and righting parameters, as well as respiratory and heart rates and haemoglobin saturation by oxygen, whereas significant differences between sexes for the parameters of ataxia, hypnosis, recovery, righting and exploratory behaviour were observed upon waking. The best results for parameters such as induction, and maintenance and recovery from anaesthesia (more regular and stable) were observed with α 2 -agonists: ketamine/xylazine in males and ketamine/medetomidine in females.

Minimum inhibitory concentration (MIC) and mutant prevention concentration (MPC) of veterinary fluoroquinolones as enrofloxacin, its metabolite ciprofloxacin, danofloxacin, difloxacin and marbofloxacin against strains (n=24) isolated from milk of sheep and goats affected by clinical mastitis were evaluated. The authors have used the MIC and MPC, as well as the pharmacokinetic-pharmacodynamic relationships in plasma and milk. MIC values were significantly different between drugs, unlike MPC values. Lower MIC values were obtained for danofloxacin and difloxacin, middle and higher values for enrofloxacin, ciprofloxacin and marbofloxacin. However, differences in MPC values were not found between drugs. At conventional doses, the AUC/MIC and AUC/MPC ratios were close to 30-80 hours and 5-30 hours, with exception of danofloxacin, in plasma and milk. The time inside the mutant selection window (T) was close to 3-6 hours for enrofloxacin, ciprofloxacin and marbofloxacin, near to 8 hours for danofloxacin and 12-22 hours for difloxacin. From these data, the mutant selection window could be higher for danofloxacin and difloxacin compared with the other fluoroquinolones tested. The authors concluded that enrofloxacin and marbofloxacin, at conventional doses, could prevent the selection of bacterial subpopulations of , unlike danofloxacin and difloxacin, where higher doses could be used.

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ABSTRACT:The aim of this study was to compare some depressors of the central nervous system combined with ketamine in order to find an adequate scombination for anaesthesia in mice, coupled with a simple, easy to use and reliable method. Forty Swiss OF-1 mice (Mus musculus), 20 females and 20 males with a body weight from 35 to 45 g aged from 12 to 16 weeks, were used to evaluate one of the following central nervous system depressors (CNSD): acepromazine (5 mg/kg), diazepam (5 mg/kg), medetomidine (1 mg/kg), midazolam (5 mg/kg) and xylazine (10 mg/kg) combined with the dissociative anaesthetic ketamine (100 mg/kg) by the intraperitoneal route. Different parameters were evaluated at regular intervals to assess the depth of anaesthesia (time of induction, time of loss and recovery of pedal withdrawal reflex, time of recovery from the anaesthesia), and respiratory and heart rate and oxygen saturation. Most of the assessment times and physiological parameters were exhibited earlier in females than in males but, in most cases, these differences were not significant. The diazepam combination resulted in death in half of the male group. Significant differences for the combination comparison were found for induction, pedal withdrawal reflex and recovery from anaesthesia, as well as for respiratory and heart rate and oxygen saturation. The best results for mice of both genders, i.e. induction, maintenance and recovery from anaesthesia were more stable with α 2 -agonists than with other combinations (benzodiazepines or acepromazine), which did not reach a good anaesthetic level, that is, an adequate anaesthetic plane with an absence of the pedal withdrawal reflex and the maintenance of stable vital constants.