[Veterinary dentistry (13). Evaluation of the use of medetomidine and ketamine to induce anaesthesia in dogs undergoing dental surgery].

The use of a combination of medetomidine and ketamine as anaesthetic for dental surgery was investigated in 60 dogs. The nature of the interventions varied from inspection of the teeth with cleaning of the teeth or simple tooth extraction to extraction of one or more dental elements or endodontic treatment. The operations lasted between 20 and 70 minutes, with an average of 34 +/- 15 minutes. Medetomidine, 1000 micrograms/m2 body surface administered intramuscularly, was used as premedication. Anaesthesia was induced with intravenously administered ketamine at a dose of 2-3 mg/kg body weight. The effect of premedication was 'good' in 79.5% of patients, 'moderate' in 12%, and 'poor' in 8.5%. Seven patients were given additional 50% medetomidine, which caused the proportion of animals with 'good' premedication to increase to 91.5%. Twelve of the 60 patients showed convulsion-like symptoms of varying severity directly after the administration of ketamine. In 4 patients the tonic cramps were considered severe enough to warrant once-only administration of midazolam. The quality of anaesthesia in the maintenance phase was considered 'good' in 88% of the patients and 'moderate' in 12%. Recovery was 'good' in 74% of the patients, 'moderate' in 11%, and 'poor' in 15%. Heart rate after premedication with medetomidine was 53 +/- 3 beats per minute and increased to 86 +/- 4 beats per minute (P < 0.05) after administration of ketamine. It thereafter decreased, over a period of 20 minutes, to 60 +/- 3 beats per minute. The respiration rate was 15 +/- 1 per minute and remained unchanged throughout the operation. After completion of surgery, medetomidine was antagonized with atipamezole (2500 micrograms/m2) given intramuscularly. In 13% of the animals the recovery period was characterized by tremors and restlessness. It can be concluded that the combination medetomidine and ketamine provides adequate analgesia, hypnosis, and muscle relaxation for various dental surgical interventions to be performed.