The effects of midazolam as a preanesthetic agent on heart rate, arterial pressure, blood gases and hematology were examined in thoroughbred horses. Additionally, premedications with various doses of midazolam/xylazine or midazolam/xylazine prior to anesthetic induction with ketamine were evaluated. With midazolam alone at doses of 0. 05, 0.1 and 0.2 mg/kg (i.v.) or 0.05 and 0.1 mg/kg (i.m.), no significant differences in vital signs and hematology were observed. The depth of sedation was dose dependent in all horses however most i.v. doses produced severe muscular twitching. The half life of midazolam in plasma was approximately 2 hours. Various i.v. doses of midazolam combined with either 0.5 or 1.0 mg/kg of xylazine produced only minimal changes in arterial pressure and their sedative efffects as premedication were satisfactory. A minimal incidence of twitching was observed at 0.01 mg/kg of midazolam when combined with xylazine. Anesthesia with ketamine (2.5 mg/kg, i.v.) following various doses of midazolam/xylazine produced no changes in vital signs. Muscular twitching and inadequate relaxation were sometimes observed at 0.05 and 0.03 mg/kg of midazolam. Thus, midazolam at iv. dose of 0.01 mg/kg combined with xylazine was considered to be useful prior to anesthesia with ketamine in horses.

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Six dogs of various breeds and sexes with the age ranging from 10 to 13 years old were diagnosed for hepatic neoplasm by clinical signs, biochemical analyses, ultrasonography and radiography including computed tomography (CT) . On CT images, the masses in the liver of 4 cases were located in the left lateral lobe and those of two other cases in the left medial lobe. Tumors were classified according to the criteria for human liver cancer. In 5 of 6 cases, tumors infiltrated into the lobe and were classified as massive pattern, whereas in the other case, tumor formed the nodule in the lobe and was clearly circumscribed from the surrounding normal liver tissue, which was classified as nodular pattern. All the animals received liver lobectomy under inhalation anesthesia. Definitive diagnosis of primary hepatocellular carcinoma was based on the histopathological examination of the resected liver specimen. Two cases died of renal failure or of respiratory insufficiency on the 18 th and the 35 th postoperative day, respectively. Two cases survived for over a year after the operation. One of them died of the recurrence of the tumor 14 months after the operation and the other died of other complication unrelated to the recurrence of the tumor. The other two cases are still surviving without developing any major complication. These results suggest that surgical resection of the liver lobe with both nodular and massive types could prolong the life of canine patients if the mass exists in a single lobe.

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We studied whether the spinal cord evoked potential which was obtained from spinal cord stimulation could be applied to small animal clinical use. Five normal adult mongrel dogs and a mongrel puppy with spinal damage were used. To record the basic wave pattern, laminectomy was performed on the 12th and 13th thoracic vertebrae and the 5th and 6th lumbar vertebrae in 2 normal animals, and 2 bipolar electrodes were inserted under fluoroscopy into the exposed epidural region. In 3 other normal animals, electrodes consisting of epidural needles were inserted into the cerebellomedullary cistern and the 6th and 7th lumbar vertebrae by puncture. In the dog with spinal damage, a stimulating electrode was inserted into the cerebellomedullary cistern, and recordings were made at various points with a wide exposure of the lesion. In the normal dogs, changes in the wave pattern was observed with different positions of the stimulating or recording electrodes placed on or near the spinal cord, and with different stimulating intensity. Acute spinal pressure resulted in the changes of the wave pattern of the spinal cord evoked potential. The normal wave pattern was recorded frequently as a two-peaked negative potential. Recordings with the electrode placed on the exposed epidural cavity had the same wave patterns as those with the electrode by puncture. In clinical use recordings by puncture will be a better method because of easiness and safety. In the acute pressure experiment, the delay of latency and decrease of amplitude were observed with the intensity of pressure. In the clinical case, when the recording electrode was transferred along the spinal cord from the cranial site to the caudal site through the lesion, the decrease of amplitude was observed as the electrode approached the disordered region : a positive wave pattern was recorded at the disordered region, and then no potential was recorded if the electrode passed over the disordered region. This proves that an conduction disorder was in presence at the disordered region, suggesting the possibility of its clinical application.

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