Initially the wall of the encysted spore (sporont) has two layers. This hydrocele also transilluminates, and is known as an encysted hydrocele of the cord. Infection in most adult dogs is characterized by encysted second stage larvae. The encysted forms may remain viable for up to 100 years. Encysted protozoan pathogens may require higher temperatures to remove any risk. However, "Cryptocaryon" can spend a much longer time encysted. Encysted metacercarial stages and free-living cercarial stages do not feed. As with "T. canis", encysted second stage larvae in pregnant or lactating cats become reactivated. Encysted cercariae become metacercariae, a dormant parasite stage with a thin outer membrane. Adequate cooking or freezing of freshwater fish will kill the encysted fish tapeworm larvae.