Note 5

When you leave your world with your wolf or cat sitting down, when you enter back into the world the wolf or cat stands right back up. I want them to stay in one place!

Steps to duplicate
1. Start a creative world.
2. Spawn and Tame 2 wolves.
3. Walk around for about a minute allowing the wolves to follow you.
4. Make both wolves sit.
5. Reopen your world.

Conclusion
At least one of your wolves is now standing up. To confirm this walk around a bit, you will noticed one of the wolves you told to sit earlier is now following you again!