Perhaps we're musical as well as independent like the New Guinea singing dog. A mule is not a pet types, like a horse or donkey. Cysts are shed or passed from the contaminated animal through its feces. Some trophozoites do not enter into the cyst form however obtain entered the feces. However, trophozoites can not survive for long in the environment and also are unable to cause infection if consumed by another pet. Upon getting to the small intestinal tracts, the trophozoites exit the cysts, fully grown, divide, and at some point go back right into cyst form.