Wolves and dogs attack skeæetons only if skeleton and dog look each other in the eye. If skeleton cannot see dog, dog will not attack skeleton. 

To reproduce, spawn in a wolf, tame it to become dog.

Make a cage with 1x1 hole on top and one block free space on bottom, to allow dog to attack. Spawn a skeleton into the cage, so its legs are free but it cannot see.

Expected: Dog attacks skeleton legs.

Observed: Dog remains passive.

Remove cage and observe that dog now attacks.

Comparable to tracker no. 148047 on Java.