Dog untamed?

My dog is suddenly untamed and stuck.

What I expected to happen was...: When I right clicked my dog, i expected him to stand up

What actually happened was...:He didnt respond. Also, I noticed he didnt have a red collar.

Steps to Reproduce:
1. Start Minecraft Singleplayer
2. Start a survival world and tame a dog.
3. Make him sit.
4. Save and quit.
5. Start world up again.
6. Try to make dog stand up again.
7. Notice he no longer has a collar.