How big is your dog now?  How big it will be in the future?

The start up pet stroller can hold pets up to 30LB, the heavy duty model can hold pets up to 45lb and the top notch pet jogger stroller can hold pets up to 75LB, like everything else, give your pets some room to grow, in general, the larger the stroller, the more expensive it is.

What's the cargo size of the pet stroller?

Weight is not the only concern you have, you also need to make sure your pets have enough room inside the stroller cargo so both you and your pets can enjoy the ride.

How many pets do you have?

More and more family have more than one pets now and not all the pets get along that well in the small cargo space, consider twin/double stroller if needed.  Side by side double stroller offer your pets more space and in general have stronger frame than up and down model.

What's the handle height?  How tall are you?

The handle height start from 33" in some small stroller to 44" for the jogger stroller, you do not want to bend over to push the stroller, do you?

What kind of wheels you get from the Pet Stroller?

All pet stroller wheels either made by plastic or rubber(for jogger stroller), but there is a huge difference between recycled plastic and original plastic, recycled plastic wheel is easy to bend and broken, make sure you get original plastic wheels for your pet stroller, anyway, you want your stroller to last, do you?

What's the size of the wheel?

The smallest size is 4", the biggest is 12", the bigger the wheel, the easier it is for you to push it.

How easy it is to fold?

most of the stroller in the market has two hand fold, you need bend over to fold the stroller with two hands, consider a one hand fold stroller, it does not cost that much more but it will make your life much easier in the long time.

Does the seller has the inventory or he is only doing drop shipping.

There is nothing wrong to do drop shipping, but it will take longer time to get your stroller and if there is an issue, it will be more complicated to resolve it.