my mom has a chi/pom/pek/shih tzu mix nuetered male who is 3 years old. last night he started chattering his teeth together, picking at a stings on blanket with his teeth and has been acting really lathargic, to the point where he wont come to her when called. he is usually a little gaurd dog, up at the drop of a pin and always at her feet. she hasn't fed him anything out of the norm. anything that anyone can think of that might be wrong please do tell. thanks.