I feel like the added pressure of having to try and form clear and precise sentences towards another person, in order to have a conversation, makes a stutter worse. As you’d be focusing more on trying not to embarrass yourself, trying to figure out what words you’re going to stutter on, or what words you could use to substitute the original words you’d usually stutter on etc. But with pets, they don’t exactly talk back. They’re just innocent living beings filled with love and affection. So you wouldn’t have to worry about being judged or anything like that. You can just be yourself and show your flaws around them. That’s just my personal view on it.