(Note: I understand that there are similar issues highlighted, but I haven't found any which describe accurately how to reproduce the situation. Apologies in advance if this is a duplicate of a similar issue, as so many have been.)

Basically, as described in other tickets, tamed cats and dogs will eventually sit and will not stand back up, despite numerous efforts and attempts to get them to do so. They will not protect you from mobs, and will basically only pivot around on the point or move if you, as the player, bump into them. I don't know what to have expected, as to whether the error would have been fixed with 1.8.1 or not, but it evidently hasn't.

How to reproduce: I spend a while trying to figure this glitch out, including switching repeatedly between game modes, difficulty levels, etc, but nothing on that level made the animals glitch. I tried 'save and quit to title' and then went back into the world, and the animals were still responding fine at this stage. However, when I fully shut down the game and reopened it, the animals had glitched, were sitting, and would not stand up. Through more experimentation, I found that it doesn't matter whether the animals were standing or sitting before you completely quit out of the game and they glitched (I repeated this a few times to see if it was an once-off error), as they would be sitting when I logged back in.

(Note: I attempted to attach an image to the issue, but I don't have permission to do so. If a screenshot is required of the glitch, I can provide.)