So your answer is that if my cat has fip and I keep him there is no danger to my other cats? The Vet who is treating him implied it was contagious.
FIP is not a highly contagious disease, since by the time the cat develops clinical disease only a small amount of virus is being shed.
Feline coronavirus can be found in large quantities in the saliva and feces of cats during the acute infection, and to a lesser extent in recovered or carrier cats, so it can be transmitted through cat-to-cat contact and exposure to feces. The virus can also live in the environment for several weeks. The most common transmission of feline coronavirus occurs when infected female cats pass along the virus to their kittens, usually when the kittens are between five and eight weeks of age.