If you tie a lead on a fence with some animal on, and then leave so far that chunks despawn leads despawn too.
So when you came back you have no lead and probably animal escapes.
MC-33533
Leads despawn if chunks despawn
Resolved
Duplicate
0
CyberBlacktation
(Unassigned)
Unconfirmed
animal, chunks, despawn, leads
Minecraft 1.6.4, Minecraft 13w39b
Retrieved
This is so annoying. It happens while going into the Nether & on rare occasion, logging off. One time my horses walked a couple hundred blocks away into a birch forest.