5. You and the dog are really, really old
4. Dog has no legs
3. You can’t have a human baby (sort of a mental crutch)
2. Grocery shopping with your dog is allowed (So many times I've wanted to kill two birds with one stone by picking up milk at the grocery store, while walking my dog!)
1. PRE-boarding on flights! (I may actually buy a stroller for this reason alone!)
Other than that, WALK your dog or leave ‘em at home. But please don't get a stroller for your dog.