Older Dog Behaves Badly

Question
Hello - we have an 11 year old Lab/Ridgeback mix who is very happy and healthy. He does suffer from hip arthrightis but is on Rimadyl and carafate, plus all kinds of glucosamine and condroitin. He seems to be just fine. The reason I am writing is that the past month or so we have (I am embaressed to write this!) caught him both licking other dog's urine and eating their fecal waste while we are outside on walks. He has NEVER done this before and now we are monitoring his every move, being very freaked out by this odd and gross new behavior.
In your experience, is this a sign of something? Is he feeling sick? Or maybe getting a little loopy in his old age? We know it isn't enough to warrant a Vet visit so we decided to write for your opinion.
Any feedback would be great! Thanks!

Answer
It could be the start of something. I would take it seriously since he never did this before.

What you CAN do in the meantime is walk him on a short leash. Unfortunately giving him ACCENT (MSG) to make fecal waste taste bad won't work unless its his feces he is eating.

I'd take him in for some bloodwork. :)