Synonym: Trichomonas bovis Pavlov and Dimitrov, 1957, non Trichomonas bovis Riedmuller, 1930.
Location: Large intestine.
Geographic Distribution: Bulgaria.
Morphology: This species was described by Pavlov and Dimitrov (1957). The trophozoites are piriform and usually measure 11 to 12 by 6 to 7 u. The 4 anterior flagella are about the same length as the body. The undulating membrane is well developed, with 2 to 4 waves, and extends almost to the posterior end of the body. A posterior free flagelium, an accessory filament and a costa are present. The nucleus is round-oval or oval. The axostyle is relatively weak and slender, broadening to form a capitulum at the anterior end, and extending about 1/4 of its length from the posterior end of the body. There are many food vacuoles in the cytoplasm.
Pathogenesis: Pavlov and Dimitrov (1957) found this species in the feces of calves 5 days to 4 months old, all of which had diarrhea. They thought that the protozoa were the cause of the diarrhea, basing their opinion on their inability to find another cause and on the fact that the trichomonads disappeared from the feces when the diarrhea ceased. Needless to say, this is not sufficient justification for their view.
Remarks: Further study is necessary to be sure whether this species is valid. Pending such a study, it is considered best to retain it. Pavlov and Dimitrov (1957) named this species Trichomonas bovis. This name is a homonym of Trichomonas bovis Riedmuller, 1930, which is in turn a synonym of Tritrichomonas foetus (Riedmuller, 1928). Hence I am renaming it Trichomonas pavlovi nom. nov.