GAS HANDLING IN THE CECUM OF THE HORSE

Electromanometric recordings of caecal pressures were made in chronica lly cannulated ponies. Endoscopy allowed direct observation of the cae cal base and cupola while recording intracaecal pressures and enabled a functional interpretation of caecal pressure profiles. Using gas-tig ht seals, the caecal gas cap baseline pressure (tone) was usually belo w atmosphere, becoming less negative postprandially. Diurnal variation s were observed in the amplitude and frequency of caecal pressure prof iles and the direction of caecal movements, during which intra-caecal gas cap pressures briefly became positive. A paraprandial (psychic) ph ase of enhanced caecal motility was observed. Manipulation of the caec al gas cap volume, by insufflation of nitrogen gas, demonstrated the c apacity of the caecal base to regulate gas pressures and to eliminate fermenting gases.