Hi, i have a young english bullterrier. She is the sweetest thing on earth, and wennever she spot other dogs or humans she goes in partymode(sometimes she seems to love other people more then me).. But 6days ago she started with some very wird, and annoying behavior..

So, everyday i go to my grandparents house. My grandma loves my dog etc, and my dog her. But for some stupid reason my granddad has a huge fear for my dog, wich wasnt a problem til last thursday.. It began to growl - pull - and jump like it want to attack him??? And its hairs on neck etc is up in full combat style.. Now each day my dog does this if it see my "nono" and today it also allmost jumped my cousin(who is also a hysterical kid). Im sure it can sense their fear, maybe it dont understand how to process this stuff yet?

Note: I have been keeping my dog in a leach since thursday, as i dont wanna see if she wanna bite or just fooling around. It does wipe around its tail while growling and its ears is straight forward. But im no expert in this matter, so i hope someone might have an idea here?

Thanks in advance.