My pets were gathered fairly close together. The log lists each pet as simply being killed by a specific individual NPC, such as “Growly killed by Stygian Soldier I”. Growly was a Level 20 Greater Sabertooth Tiger and while not following me has 37 Strength and something like 6000 health.

A friend on my server suggested that maybe someone deliberately forced a purge on nearby unclaimed land next to my base to kill my pets. I do not know if that is possible. Is it?