I travel with my dog all the time in the cabin. Delta, unlike some other airlines does not have a weight restriction. NW comes to mind as a maximum of 15 pounds including the carrier. My dog is 15 to 16 pounds and fits in the Large Sherpa bag very nicely. I would second the post that recommended this bag. It is soft and fits well under the seat. I would get your dog used to the carrier before you actually fly. Also to minimize issues with the dog having to go, make sure the dog does not eat before the flight and limit liquids, and walk the dog one last time right before you enter security. My dog has been on flights for over 10 hours without a problem. I never sedate her, but she is used to flying. Check with your vet on the sedation since there are two schools of thought on the advisability of it. I should note that all my travel has been domestic. Good luck.