Most pet carriers that have wheels are soft-sided. They also have mesh ventilation which makes it easy for your pet to be able to see around him, to get fresh air and also to breathe comfortably.
To determine the minimum length and height requirement of the carrier you should choose, be sure to measure your pet. Measure from the floor to the top of your pet’s shoulder for his height. The length will be a measurement from your pet’s neck to the base of the tail. Add 2-3 inches in each direction so you’re sure your pet is able to turn around inside the carrier.
Similar to strollers, the weight limit stated is only a guide. You certainly do not want to purchase a carrier that isn’t capable of supporting your pet’s weight. It is wise to choose a pet carrier that is able to hold about 5 more pounds than your dog weighs.
For example, a Shih Tzu that weighs 12 lbs, and measures 14″ long and 9″ high will fit comfortably in a Pet Gear World Traveler with Wheels, large size. He will also be happy in a medium Sherpa Pet carrier with wheels, and the Snoozer Roll Around, to name a few.
More wheeled pet carriers can be found at PerfectPetStroller.com