Etiology: Tritrichomonas species (muris, minuta), Trichomitus wenyoni and Tetratrichomonas microti are protozoa which infect rats.
Incidence: The incidence of infection is common.
Transmission: Fecal-oral transmission occurs via ingestion of pseudocysts.
Distribution: These protozoa inhabit the cecal and colonic lumens. They retrograde into the small intestine.
Clinical Signs: No clinical signs have been attributed directly to these organisms. Diarrhea may be exacerbated by the presence of these flagellates, however their role as contributors to disease is poorly defined.
Diagnosis:
Antemortem: Direct smear of feces, fecal PCR.
Postmortem: Wet mounts of cecal contents reveal slow moving, flagellated protozoa with an undulating membrane. Trichomonads move with a jerky, wobbly, undirected motion.
Histopathologic examination may also be used to diagnose trichomonad infection.
Diagnostic morphology: Trophozoites are pear- to lemon-shaped with an undulating membrane and 3 (tri-) to 4 (tetra-) anterior flagella. There is NO true cyst form.
T. muris 16-26 x 10-14 µm
T. wenyoni 6-16 x 3-6 µm
T. minuta 4-9 x 2-5 µm
Etiology: Chilomastix bettencorti is a flagellated protozoan.
Incidence: The incidence of infection is common.
Transmission: Fecal-oral transmission occurs via ingestion of infective cysts.
Distribution: Chilomastix bettencorti is distributed in the cecum and colon.
Clinical signs: No clinical signs have been attributed directly to these organisms. These protozoa may proliferate in diarrheic states, however their role as contributors to disease is poorly defined.
Diagnosis:
Antemortem: Difficult to diagnose from fecal pellet samples. Wet mounts of fresh fecal material stained with a weak iodine solution may reveal typical lemon-shaped cysts that can be difficult to distinguish from plant material.
Postmortem: Wet mounts of intestinal contents may reveal pear-shaped trophozoites with a spiraling, jerky motion. The spiraling motion will aid in differentiation of Chilomastix trophozoites from trichomonads.
Diagnostic morphology: Trophozoite: 10-15 µm long, pear- or lemon-shaped with 3 anterior flagella, a round anterior nucleus, a short, sharply pointed tail and a large cytostomal groove. Cyst: 6-9 µm, lemon-shaped.
Etiology: Giardia muris is a flagellated protozoan.
Incidence: The incidence of infection is rare.
Transmission: Fecal-oral transmission via ingestion of infective cysts.
Distribution: Giardia muris is found in the anterior small intestine.
Clinical signs: No clinical signs have been attributed directly to these organisms. These protozoa may proliferate in diarrheic states, however their role as contributors to disease is poorly defined.
Diagnosis:
Antemortem: PCR of feces can be used to diagnose Giardia infection antemortem. Wet mounts of fresh fecal material or use of sucrose gradient may reveal cyst forms (difficult).
Postmortem: Wet mounts of intestinal contents may reveal slow-moving flagellated protozoa with a “falling leaf” rolling motility. Histopathologic examination may also be used to diagnose Giardia species infection.
Diagnostic morphology: Broad, piriform trophozoite with 2 anterior nuclei that when stained with weak iodine solution gives the appearance of a “monkey face.” There are 8 caudally directed flagella.
Etiology: Spironucleus muris is a flagellated protozoan.
Incidence: The incidence of infection is rare in research settings.
Transmission: Ingestion of infective cysts passed in fecal material is the primary mode of transmission.
Distribution: Spironucleus muris is found primarily in the crypts of the duodenum and pyloric glands. In young animals, luminal protozoa are more numerous.
Clinical Signs: Clinical signs are not usually observed.
Diagnosis: PCR of the feces can be used however, cysts are shed intermittently. Direct smears of small intestinal contents reveal fast darting protozoa. Spironucleus can also be diagnosed by histopathologic examination of pyloric/duodenal area.
Diagnostic Morphology: Trophozoite: 7- 9 x 2- 3 µm, piriform (teardrop)-shaped or carrot-shaped, with 6 anterior flagella, 2 posterior flagella, 2 anterior nuclei and 2 separate axostyles.