It's just an expression....

[nwfloridafalconfan]

This works!  Molly, our 15+ year old Chow mix, has always been a low maintenance girl, but now, due to a combination of hip discomfort and doggie dementia, she is having trouble remembering to "go" while outdoors.  A gentle expression of her bladder every six to eight hours has greatly reduced stress, frustration, and running of the "Little Green Machine" carpet cleaner!

http://www.handicappedpets.com/how-to-express-your-dogs-bladder.html

http://vetmedicine.about.com/od/dogdiseasesconditions/tp/canine-dementia.htm

[Donna]

This is very good info, thanks Paul! Glad it's helping your Molly.