Eighteen mixed bread males and females dogs, with abodyweight óf 12.9 ± 3.2 kg, were allocated into ttivo experimental groups, in order to study the effects of epidural anaesthesia with hostacain (2%) in a single dose of 0.5 ml / kg (Group 1). The group 2 was premedicated with diazepam in a dose of 1 mg/kg, intravenously 5 minutes before hostacain. Physiologycal values (arterial pressure, heart rate and respiratory cate) and anesthesiologycal values (latency} period, epidural anaesthetic period and recover'y period) were determined.The results sholved a decrease in the minimal and maximal arterial pressure and increase in the heart cate in both series, but these values viere no statistically sigrzificative. The respiratory rate showed a significant decrease between grorrps during the initial and medial transanaestetic period. The latency and anaesthetic period showed a significant increase in group 2, but this was not absorved during recovery anaesthetic period. The result suggests that the association diazepam hostacain should be useful due to the facility, of handling dogs and to the longer time of anaesthesia obtained, without disturb on the recovery period and physiologycal variables.Se estudia en 18 perros mestizos de ambos sexos, el efecto sobre las variables fisiológicas y anestesiológicas de la anestesia epidual realizada con hostacaína 2% (0,5 ml/kg) sola y premedicada con diazepam (1 mg/kg) endovenoso. Esta asociación resulta adecuada para el perro ya que el diazepam no aumenta la caída de la presión arterial inducida por hostacaína. La frecuencia cardíaca experimenta un aumento no significativo y la depresión respiratoria no pasa a constituir riesgo de vida para el animal. Además con diazepam aumenta el periodo de latencia y el de anestesia y disminuye el de recuperación.