Oscar has only ever howled when he was waking up after his amputation. I think it was pain related as he carried on until he had more morphine.

Alfie has howled a few times in his sleep, when hes having a dream. Its a very haunting sound.

__________________

I am just a worthless liar.
I am just an imbecile.
I will only complicate you.
Trust in me and fall as well.
I will find a center in you.
I will chew it up and leave,
I will work to elevate you
just enough to bring you down