I have a dog (chihuahua) and a cat who live very harmoniously together. However, the dog has started reacting to any cat that wanders in to our garden. She used to just chase after them but the last time it developed into her giving the cat a nip as it ran off. I happened to see it and told her no and sent her back inside. Last night I took her out for her night time wee and as she ran off into the darkness I suddenly hear a commotion between her and a cat. It sounded like a fight. I called her back and she did return to me but I am worried our neighbours - the cats owners - are going to turn up in my doorstep one day with a vets bill!! DH says our dog is in her own garden and if the cat a stupid enough to keep returning then it is it’s own fault. But I am worried both about the cat and my dogs behaviour. Any advice?