Hoping there is no blockage or any other serious problem. Our bulldog and maltese are the first dogs we raised inside our home. All my other dogs were outside and other than seeing them poop when watching or seeing the results later, it was never monitored as closely as we do ours now. So if they missed a day or two even I probably would not have noticed. But maybe just like humans there is no apparent reason for constipation and in time just passes. There is always a reason but it may just be a cyclical thing, or a little less exercise, water, allergies, allergy meds who knows. I hope its just something that will pass in time.