I'm adopting a cat from a rescue who advises to retest my 4 month old kitty for FIV even though his first test came back negative. The rescue people didn't really stress it nor did they know much about it. I read online that it isn't necessary to retest if the initial test was negative - is this true? For what it's worth, the kitten's mother didn't have FIV and the kittens haven't been outside, so the chances are extremely slim.