My tamed animals have disappeared

I logged on.

I walked around and over to the area I keep my dogs, horses and sheep and a pig. (All animals that can't be tamed were name tagged.)

Only one dog was there, just one dog.

All other animals had just completely gone.

This is in the one area of my world that was loaded in when I left the world,

all other places that were not loaded in, aren't affected.