One group of trematodes found in the intestine of cats are Cyathocotylids, represented by the genera Mesostephanus and Prohemistomum. The adults of these trematodes parasitize the intestine of piscivorous reptiles, birds, and mammals. These flukes are characterized by the presence of a glandular tribocytic organ that is present in addition to the ventral sucker (The ventral sucker is absent in some genera.). The body may be weakly divided into forebody and hindbody regions, and a cirrus sac is present at the posterior end of the body.

Besides natural infections with Mesostephanusmilvi and Prohemistomum vivax (discussed below), cats have been reported to have been experimentally infected with Mesostephanusappendiculatus in Romania and with Prohemistomumvivax in Egypt by feeding them infected fish (Chandler AC. 1950. Mesostephanuslongisaccus a new Cyathocotylid trematode from a dog. J Parasitol. 46: ???).