The first thing I would do is contact owner and ask them if they know of any food problems. I would also put a leash on her at feeding time so you have control of her and if she gets too aggressive I would use the leash to hold her back a bit until she settles then allow her to eat. Do not let her have control over you because she will keep using it. I would also try a water bottle and if she snaps spray her in the face so she knows it is not okay for her to do that. You may be best to do all of those together.