Laboratory animals
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Heart rate, arterial blood pressure and blood acid-base status were determined in 18 adult female mink (mean (+/- SEM) body weight 1052 +/- 34 g) during long-term anaesthesia with either controlled ventilation (n=12) or spontaneous respiration (n=6). Surgical anaesthesia was induced by intramuscular injection of ketamine hydrochloride (Ketaminol Vet, 40.0 +/- 1.7 mg/kg) and midazolam hydrochloride (Dormicum 2.8 +/- 0.1 mg/kg) and maintained for at least 5 h by continuous intravenous infusion of this drug combination in 0.9% saline. For all animals, the mean rates of infusion of ketamine and midazolam were 48.4 +/- 1.6 and 1.61 +/- 0.12 mg/h, respectively. ⋯ It is concluded that the procedure described for long-term anaesthesia in mink is convenient and safe for acute physiological experiments in this species, provided normal body temperature and pulmonary gas exchange is sufficiently maintained. Thus, the need for an adequately controlled artificial ventilation is strongly emphasized. Finally, a proposal for the composition of an intravenous solution, containing ketamine and midazolam hydrochloride, and sodium bicarbonate in saline, suitable for long-term anaesthesia in adult mink is presented.
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An anaesthetic mask for use on guinea pigs (Cavia porcellus) in a stereotaxic frame: technical note.
A mask was designed to allow inhalation anaesthesia to be used on guinea pigs (Cavia porcellus) whilst placed in a stereotaxic frame. To date, anaesthesia has been maintained in approximately 60 animals using this method, with no mortalities.
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Mean age at vaginal opening was 41 days, range 33-53 days. Bodyweight at weaning and age at vaginal opening were negatively correlated, but there was no relationship between bodyweight and age at vaginal opening. The presence of a male before vaginal opening did not accelerate either the time of its occurrence or first conception. The vaginas of females caged singly from weaning opened earlier than in those kept in groups of 2 or 3.
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A surgical technique of performing tracheostomy in dogs requiring prolonged intubation with either cuffed or uncuffed tubes is described. Cannulae used in humans are anatomically unsuitable for the dog. The cannula and cuff described in this paper did not predispose to severe mechanical trauma to the trachea and we attempted to minimize factors that may predispose to tracheal damage during the period of intubation and the subsequent development of late tracheal injuring after extubation. A simple method of humidification in these healthy dogs proved adequate; neither tenacious tracheobronchial secretion nor the retention of secretions were seen.