BEHAVIORAL AND ELECTROENCEPHALOGRAPHIC STUDIES OF BEAGLES WITH AN ECKS FISTULA - SUITABILITY AS A MODEL OF HEPATIC-ENCEPHALOPATHY

Behavioral manifestations, electroencephalograms (EEGs) and Visually e voked potentials (VEPs) were studied in beagles with Eck's fistula (po rtacaval shunt [PCS]), an established model of hyperammonemia, to dete rmine whether they developed CNS disorders characteristic of hepatic e ncephalopathy. After PCS, behavioral changes occurred in the form of l istlessness, sluggishness (altered gait, snapping and transient catato nia-like symptoms) and apparent blindness, which appeared in that orde r and progressed to coma and death in some animals. The EEGs from the frontal cortex showed a gradual decrease in voltage and frequency. Dev elopment of snapping and catatonia-like symptoms coincided with the oc currence of high voltage fast waves in the EEGs from the occipital cor tex. In comatose Eck's fistula dogs, Battening of the EEGs was recorde d from the frontal cortex and a lowered voltage was noted in the EEGs from the occipital cortex. After PCS, the latencies and amplitudes of the components of VEP were increased. The snapping and catatonia-like symptoms were markedly ameliorated by carbamazepine and the coma by fl umazenil and thyrotropin-releasing hormone. These findings indicate th at Eck's fistula dogs provide a useful model of hepatic encephalopathy . (C) 1997 Elsevier Science Inc.