It's great to consider taking your dog with you on a trip. While you're in the planning stages, research the airlines you're considering. They all have standard guidelines as well as individual ones. General rule for inside the cabin - dog and carrier weight not to exceed 20#'s. A soft carrier has a little more give factor for under the seat. We recommend the Sherpa or AirPod brands. You have to make sure what you purchase is airline approved. Your dog needs to be able to stand, sit, lie down and turn around in a natural position. If your dog isn't used to a confined space, getting your carrier well before the trip is helpful for practice and adjustment. I would take your dog to a local store carrying airline approved carriers and test them out for size. Make sure your dog fits according to the visual and weight guidelines. Talk to your veterinarian regarding medication. It's best to be prepared in case you need to take this measure. American Airlines link is attached.