This stroller is great for a small, medium, or even big sized dog. I wouldn't go as far and say it can fit a great dane but it is definitely big and wonderful! My older 23lb dog can't walk as fast and as far anymore so I decided it was time to buy a stroller. This one was a good price and even came with an attachment for the bike. I love the stroller and I think my dog does too. My other dogs who can still walk but find it a little big and bulky and are too scared to walk past it while we are walking but I'm sure they will get used to it. I have fit my 23lb dog and a 20lb dog inside the roomy space of the stroller easily, I probably could have fit two more dogs in if I wanted to, plus my cat, and still gone on a bike ride. The thing is fantastic! The only issue I have with it is that it cannot turn very well at all. It's already bulky enough with how large it is, and turning it is pretty hard, it gives you a work out, BUT, what stroller does turn easily? Even for kids? So overall, the thing is great! It has given my older dog his quality of life back, and I can't think of a better reason to have this stroller.