Segmental lumbar epidural analgesia was evaluated in 8 adult cows (four cows were used twice at weekly interval) using 2% lidocaine (Group L), a combination of lidocaine and xylazine (Group LX), and 2% lidocaine with an intravenous injection of xylazine (Group LivX) . Analgesia was defined as a lack of response to pinprick and towel forceps pinch on the skin of the flank. A significant difference in time from drug administration to onset of analgesia among the groups was not found. Duration of analgesia was sgnificantly longer in Group LX (110.6±1.7 min) than in Group L (51.2±28.5 mm) . Analgesic area in Group L was significantly smaller than those of the other two groups. Time to obtain maximum analgesic area after epidural injection in Group LivX (12.5±11.0 min) was faster than in Group L (38.7±18.8 min) . Mild sedation in Group LX developed at 20±11.5 min after epidural injection and lasted for 100.0±11.5 min, which was significantly longer than 40.0±17.3 min in Group LivX. Pulse rate was not significantly altered in any of the groups. Respiratory rate in Group LX and Group LivX decreased at 30 and 60 min after epidural injection, but significant decrease in PaO₂ was observed only in Group LivX at 10 min after epidural injection (89.7±8.9 mmHg) . Epidural lidocaine/xylazine provided prolonged duration of analgesia, large analgesic area on the flank, mild sedation, and no effects on arterial blood gas values.

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Xylazine (0.0025 ml/kg of 2% xylazine and 4 ml of 0.9% NaCl), xylazine/lidocaine (0.0025 ml/kg of 2% xylazine and 4 ml of 2% lidocaine), or saline (0.0025 ml/kg plus 4 ml of 0.9% NaCl) was given epidurally through indwelling catheters placed 20 cm cranial from the thoracolumbar intervertebral space in 4 adult cows. Each cow received all the regimens at weekly interval in a Latin Square design. Immediately after epidural injection, the cows were cast with ropes, positioned in dorsal recumbency and restrained in this position for 60 min. Analgesia was defined as a lack of response to deep pinprick on the left and right body walls and on the middle body wall of 20×20 cm width between the xiphoid and the umbilicus (the middle area), corresponding to the incision site of the paramedian approach for abomasopexy. Though xylazine and xylazine/ lidocaine produced analgesia of the lateral body walls (max dermatomes of T7 to L3) and of the middle area 5 to 30 min after epidural injection, 2 cows given xylazine and 1 cow given xylazine/lidocaine produced imcomplete analgesia at the cranial portion of the middle area. Struggling against dorsally recumbent restraint occurred in cows of all the groups. Mean arterial blood pressure did not change in saline-injected cows, but decreased by about 20% in xylazine-and xylazine/lidocaine-injected cows at 20 and 30 min after epidural injection. Significant decrease in PaO² developed in cows of all the groups at 10 to 60 min after epidural injection but returned to normal level in 10 min after standing.

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Six horses were anesthetized with isoflurane and positioned in dorsal recumbency. End expiratory isoflurane concentration was maintained at 1.7±0.1%. Four doses of dobutamine (0.5, 1.0, 2.0 and 4.0μg/kg/min) were intravenously infused and hemodynamic responses, hematocrit and serum protein were measured. Cardiac output was significantly increased by dobutamine infusions at doses of 2.0 and 4.0μg/kg/min. Stroke volume was also increased dose dependently from 0.5 to 2.0μg/kg/min of dobutamine, however the value was not elevated at 4.0μg/kg/min. Heart rate increased at doses of 2.0 and 4.0μg/kg/min of dobutamine infusions. Mean heart rate was elevated to 71.2±16 bpm by 4.0 μg/kg/min of dobutamine. Accordingly, increased cardiac output at a dose of 4.0μg/kg/min was presumed to be due to the increases in heart rate. Systemic vascular resistance increased at doses of 0.5 and 1.0μg/kg/min, but the values at doses of 2.0 and 4.0μg/kg/min were lower than those at smaller doses of dobutamine. Mean arterial blood pressure significantly and dose dependently increased by dobutamine infusion. Therefore, mechanisms for the increases of mean arterial blood pressure by dobutamine at smaller doses (0.5, 1.0μg/kg/min) and larger doses (2.0, 4.0μg/kg/min) were different. Increases in systemic vascular resistance would be the main cause at smaller doses, but those of cardiac output at larger doses. Hematocrit significantly and dose dependently increased by dobutamine infusions, but only slight increase in serum total protein was observed.

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Rapid inhalation induction of anesthesia (RI) using 5 % isoflurane or sevoflurane with or without 67% of nitrous oxide (OI, GOT, OS and GOS) was evaluated by compaing the movements, induction and intubation time, and the cardiovascular effects in 24 beagle dogs. Induc tion time of anesthesia (223.7±29.2 sec) in OI group was significantly shorter than that in OS group (310.2±33.9 sec) . In addition, induction of anesthesia was more rapid and smoother with the use of nitrous oxide (GOT: 206.2±24.4 sec, GOS: 260.8±22.2 sec) . All the dogs of any groups showed various degree of movements during induction. However, in GOT group, movements in half of the dogs were minimal. The changes in cardiac parameters after the beginning of inhalation was remarkable, especially in heart rate. However, stabilization on circulatory and respiratory function under the maintenance level (1.5 MAC) could be attained in 10 min. Therefore, GOI is the most practical method for RII in dogs wihtout undesired effects on the airway when the maximum scale of the commercial vaporizer (5%) was used.

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