So my in-laws have a 3 year old 5lb "Shmorkie" (Shih Tzu, Maltese, Yorkie) and in the past few months when ever my father in law takes him out for exercise he is gone for at least an hour and I'm not entirely sure how far they walk but its a long ways. Before this I honestly never saw them walk the dog, I would walk him sometimes when I came over but we only went a short ways because he would tire out so fast. Anyways, as of lately he has been acting aggressive and this is the only thing that we can think of that has changed in his life. I keep telling my father in law to stop walking him so far for a few days and see if there is a difference, but he is so hard headed he ignores me and does it anyways. Everyone always says a tired dog is a happy dog, but if starting to think that for this little guy a tired dog is an angry dog.
He never used to chase after my dogs and get in their face barking/growling/snapping whenever we came in a room where he is. He snaps at my dogs if they walk up to him with their tails wagging trying to say hi like they always have. If he is on the couch or in his "dads" lap and my little old scottie dog jumps up on the couch he tries to attack him. He has also become possessive over food/bones/treats he will try to bite any human or dog that goes near him while he has it, but this is not all the time which is weird. It just depends on the mood he is in I guess. So I was wondering if anyone has ever seen a dog get crabby with too much exercise or if it has to be something else. Also he has a clean bill of health from the vet. I have never thought of the possibility of too much exercise since I have hyperactive dogs that could run all day and ask for more.
I just worry that one day my dogs will be like enough is enough and snap back and since there is such a size difference actually hurt him. They have seemed to not even care but until he gets back to his old self I don't want my dogs around him anymore, which is such a bummer because Ember grew up with him and Lucy and Zeus have known him his whole life.