I apologize for the disgusting nature of this post...
I have a 14 year-old dog who's been reliably housetrained all her
life. For the past couple years, she's been on heart meds for a CHF
condition and her diet was changed to Canine H/D. She has responded as
well to the treatment as you might expect, but because of it, she
urinates very regularly and I have found that her stool has softened
and she defecates in numerous installments.

More recently though, her bowel movements have become far less
frequent, and she often fouls up inside the home during the night. I'm
not sure if this is due to incontinence, behavioral issues or some
other problem. In her old age, her behaviour has indeed changed - she
seems less social and more greedy (snapping at treats and often raiding
the trash). I've tried to take her out as late as possible, giving her
ample time to do her business. But last night for instance, I took her
out at 1am and waited around for 20 minutes.
She was only interested in sniffing the ground, so I brought her back
home. Immediately upon returning, she went to lie down in my carpeted
room, began licking her anal region incessantly and then defecated on
the spot.

This course of events has happened several times - she doesn't do her
business when taken out, then does it soon after returning home (esp.
on my carpeting!). She's also done it several times from a lying
position. I'm taking her for a check-up later this week, but wonder if
anyone can offer insight in the meanwhile. My roomate is growing less
tolerant and I'm exhausted from middle-of-the-night cleaning duties!

many thanks,
CH