Dog's head coming off

I see the dog laying on the hammock and its head is coming off
also happened when they sat on sofas/chairs/tubs ect.
yes I know this is old but I keep finding more ;)
http://img329.imageshack.us/img329/2271/dog0jx.png

Ok that is very weird +Rep :) I have seen that one before with a cat but not with a dog.