It has been almost 48 hrs since he has had a normal BM. He goes outside and strains to poop but nothing comes out. This morning he passed a small amount of diarrhea so of course an obstruction is my biggest fear. Thankfully he is acting fine otherwise, no vomitting, and his appetite is normal. I left him with the vet this morning for observation, X-rays, or whatever else they feel is needed. I'm crossing my fingers it's just constipation but I would rather be safe than sorry. He normally poops three times a day so this is very abnormal. I will update when I hear from the vet.