The company that made the dogger asked stroller owners what they liked and didn't like about dog strollers and they made one with those recommondations.
There is a few people here that have bigger pups and have the Dogger. The actual length of the bed is longer in the dogger though then the zebra one. I can easily fit three or four dogs in it. Also the front goes up and down easily so the dogs can climb in. I have never tipped the stroller over while using it. It even has shock absorbers. I have gone on curbs, snow, ice, hills and rock. Check out the site and I think LilSis still sells it. You can ask her also about it.
Dogger? -The SUV of Dog Strollers