Is a duplicate of MCPE-130262
This might be related to MCPE-62439, MCPE-182041 and MCPE-38533
It does not seem to be an issue in 1.21. got fixed at some point
Just to add that the dog was at full life at the beggining of the figth, and the skeleton managed to hit it 3 times
This bug doenst seem to be on the querry for “open issues” on the Mojira Bug Tracker, only showing up on “all issues” still affects the game