Tamed and name tagged mobs disappearing

Hello, I earlier today was just mining out a big square of dirt not to far from my base and decided to return just to get another shovel. When I came back I noticed my cats were gone and were wondering if a mob moved them or something and didn't  think much until my horse was also gone. At that point I panicked since theres no way for it to get out and also my fish with a name tag was gone. I check around my base and everywhere and they were no where. Decided to run around to see if any random horses I tamed were there, which they were not.