Put the summary of the bug you're having here

What I expected to happen was...:
I made my wolf sit in my house, and never let him walk around. So I expected him to stay were he was and not suddenly disappear. To ensure him from despawning, which shouldn't be possible at all, I give him a name tag too. I had some horses too tied to some fences, so I expected them to stay there as well.

What actually happened was...:
After a while my wolf just disappeared, while I never allowed him to walk around the property, and my horses did too at the same time. So not only did I lose my wolf, but also 2 horses along with saddles and diamond armor.

Steps to Reproduce:
1. Make a pet wolf sit for a longer period of time