About 35 days after the initial infection, the cat s feces are unlikely to be carrying the parasitic cysts. It gives us a schedule. When we keep a cat indoors for more than 35 days, feeding only commercial cat food, we can be reasonably sure that the cat s feces will not contain toxoplasmic parasites. A healthy indoor pet cat will not become initially infected with toxoplasmosis unless the cat has access to infected feces, infected meat, infected prey, or infected raw milk. The indoor cat who eats a commercial cat food and uses only his own litter box should not become infected.
Toxoplasmosis is another good argument for keeping all pet cats as indoor cats.