I understand it's tempting to get close to wild life, I've got close encounters with moose, deer and fox myself and those crazy rabbits One time I starred a fox right in the eyes at about 20m and they where bright orange shining like fire and it felt magical. And an other time I circled a moose several times and got pretty close but every little indication that it was about to back of I turned away and that made it stay it's ground and let me come back.
But I never fly straight at them as that keeps them much calmer, and if I see that they back of or start running i immediately turn away and that may even get them to stay so that I can pass them by more then once. I don't think they'll get a heart attack if you chase them but they might injure them self, breaking legs or run into fences and such if they panic like that. And it doesn't look good if someone see you and if there would be an incident from it those things could get us banned.
I hope you'll get you're own magical encounter someday but be careful and fly responsible
Here's the fox, and he first faced me and we are both about to turn away from each other at the picture and he didn't even start running just keep on walking down to the lake. (Had my GoPro on timelapse)