Really, though, I wish he could tell me what's going on with him. I suspect he's in pain, but he's so darn stoic that he won't admit it. Denz was at the vet on Friday because he's lost a LOT of muscle in the past month - particularly along his back and in his hindquarters. He's lost 4 lbs and it seems to be all muscle. He also lays down more than usual. On the other hand, he is still always ready to go and hasn't been overtly lame.
Denzil has a known problem with his patellas. I took him to Iowa State University vet school earlier in the year. He was diagnosed w/ Grade 2 luxated patellas. Sometimes he's toe-touching lame (after very vigorous exercise - the kind Denzil's like best), but with a day or 2 of rest he's just fine. The ISU vet didn't recommend surgery, but told me it's a consideration if the problems continue.
Our orthopedic vet here didn't really find anything in a physical exam last week, and Denzil's bloodwork was ok. Tomorrow we're taking in a stool sample to rule that out. The vet also had me up Denzil's food (Denzil thinks that's the best treatment regime EVER).
I suspect that his right knee is now bothering him, too, causing him to move around less, and carry less weight on his hind end - therefore losing muscle. This is why I wish he could talk - just tell me what's wrong so we can fix it!