Geographic Distribution: United States.
Prevalence: Hegner and Ratcliffe (1927) found this species in 2 out of 28 cats examined in Baltimore, Md.
Morphology: The body is piriform, 6 to 11 by 3 to 4 u with a mean of 8 by 3 u, and has 4 anterior flagella longer than body. The costa is illustrated as prominent. The undulating membrane extends most of the body length. There is a free posterior flagellum. The axostyle extends a considerable distance beyond the body.
Geographic Distribution: United States, Europe.
Prevalence: Hegner and Ratcliffe (1927a), found this species in 22 out of 23 dogs examined in Baltimore, Md.
Morphology: The following description is based on Hegner and Ratcliffe (1927a). The body is piriform, 7 to 12 u long and 3 to 4 u wide. Four anterior flagella about as long as the body arise in pairs from a large blepharoplast. The undulating membrane extends almost the length of the body. The free posterior flagellum is about half as long as the body. The costa is apparently slender. The axostyle is thread-like, staining black with hematoxylin, and extends a considerable distance beyond the body. Subcostal granules are absent.
Remarks: An old dog with advanced gingivitis was infected with T. tenax by Hinshaw (1928); the infection was still present 14,5 months later. Simitch and Kostitch (1938) were unable to infect humans with T. canistomae or to infect dogs with T. tenax. The morphological difference described between the two species indicates that they are different. T. canistomae and T. felistomae, however, may well be the same; further study is needed to determine this.