Feel free to judge me up and down for this, but G, my little pittie, has a bicycle trailer which converts into a very large, very easy to use stroller for large dogs.
I originally purchased this stroller from Amazon.com because I really wanted to tow G up and down the Hudson River walk when I lived downtown. Lo and behold she SCREECHED the entire time she was in the thing and almost ripped it more than once.
Luckily (?), when G tore a muscle while playing at daycare, I started putting her in the stroller to take her back and forth to places she could no longer. Oddly enough, she loved it. As long as I didn't zip her full into, she would lay right down and go to sleep with her head hanging out the back. [Ed. note: Full disclosure, I ended up purchasing the following stroller conversion kit and throwing out the original wheel that came with the stroller, because it was fixed and didn't rotate. This meant that every time I tried to turn the thing, I would have to push down on the handle lift the front section off the ground - a pain in the behind when you're 44 lb. dog is asleep over the front wheel. This rotating wheel has been the BEST!]
Now I use it when I go to pick up dog food or take her to the vet in midtown. I've gotten stares and comments, mostly positive, but not all. I've stopped more and more feeling like I need to give an excuse ("She's hurt, she's limping, she's tired.") and have just owned up to the fact that, at least for me, this stroller behemoth really works (and it's a pretty sweet bicycle trailer too, if your pup is into that sort of thing!).