United Airlines has a pet policy that allows for the transportation of your dog or cat in the cabin of their carrier. United Airlines Pet Policy that states that you must pay for all pet-related expenses, including boarding and travel-related items. If you are traveling with your dog or cat, you must contact United Airlines at least 14 days before your trip to request a carrier and be able to provide documentation of their vaccinations. You will also need to bring any necessary quarantine certificates and other documents.