My little yorkie Jesse is really possessive over me. For instance if I'm holding her on my lap and the cat comes over she leaps up and snaps at it. I wouldn't say that that was because she is a dog and the cat is a cat because she and the cat get along really well together if I'm not around. Jesse is only aggressive if I am giving her attention. I want to know how I can fix this because she does it to the other dogs as well and I'm afraid if I let it slip by she might get aggressive to humans but just telling her no when she does it doesn't seem to work.