[Rescuemomma]

If this started when you moved into the new apartment (you mentioned you just moved into a 1 bedroom), it may be he can smell where dogs have gone in that apartment before. Getting the carpets cleaned professionally and make sure they use an enzyme pet treatment when they do it may help. But I agree, that this could easily be medical, especially at his age, and if he where my dog, I'd say a senior blood panel and urinalysis would be the first thing on my "to do" list. There are dozens of medical problems, especially in early stages, that can cause that, and can be easily treated or managed if caught early enough, but if allowed to progress they become much more difficult if not impossible to treat. A UTI could be making it painful for him to pee on his pad, so when that discomfort is combined you being gone, the combination is to much, and he urinates off the pad. When you're there, that anxiety/discomfort is gone, and he'll use it. This may or may not be the case, but honestly, I agree that at a bare minimum I'd be taking a urine sample in for a UA, UTIs can quickly damage the kidney if left untreated, especially in older dogs.