I have a 7 yo Basenji who is very attached to me and has lived with me since 9 weeks old. Lately, he refuses to poop when we go out for walks. He goes right away if my father or friends walk him. Since I live alone, it isn’t always possible to get someone else to take him out so he ends up just farting for hours. Changing or repeating locations or schedules seems to make no difference. Any advice?