It's nothing short of a miracle that the dog wasn't injured/shot if it had been Jeremy,he would have shot it because it would have been biting his ankles ( having bitten him on one occasion,the reason he hadn't liked the dog ) Instead,JB had shown no signs of the dog having bitten him on this night.
Those particular dogs are mainly owned by women and like Crispy are allowed the run of the home as well as having an aversion for male company where a female is " master ".
I wonder if the " graze " on Sheila's lower abdomen had been caused by the dog jumping up at her at some point ? The injury was low enough for the dog to have reached.