Comparative study of cardiovascular, neurological and metabolic side effects of 8 narcotics in dogs. Pethidine, piritramide, morphine, phenoperidine, fentanyl, R 39 209, sufentanil, R 34 995. I. Comparative study on the acute toxicity and hemodynamic effects of the narcotics in high and massive doses in curarised and mechanically ventilated dogs.