Our first round of travelling nomadically in Central America, we did not have a dog. Now we realize how relatively simple it was to transport from one place to another with just us humans to worry about. But, getting our beloved pooch overseas wasn't actually has difficult as we thought it might be. When we first decided to go to Spain, we had about two weeks for our plan to work. So within two short weeks, we satisfied all the requirements to get Bella on our lap the whole journey.
First is the top level research that depends on where you're coming from and where you're going. Of course, the accommodation you choose also need to be dog friendly, which is easily accomplished by communicating with the host. Since travelling with Bella, we always make sure the accommodation has some kind of private yard area. This save so much time and energy because we don't have to suit and gear up for a full walk to let her do her business. The requirements for the country as well as the mode of travel need to be considered. Every country has different laws about what incoming dogs need to have. You can expect to need their shot up to date, but beyond that it varies wildly. For example, going to Spain. we needed her shots up to date, a microchip (which she already had), and a special certificate that functions like a pet passport. Most of the EU countries were similar, but Ireland had special requirements for tapeworm treatments needing to be done in a certain time frame. It's actually quite easy to find a comprehensive list of requirements for any country on their government websites. You can go to the vet with this list in hand and they can help determine which things still need to be done based on your pet's records.
Note that the following airline tips mainly apply to small dogs that actually can fit on your lap. If you were traveling with a larger dog, I believe the only option would be to put them in the cargo holding. Whether this is viable depends on the temperament of your dog, but it's relatively straight-forward in that most airlines will let you do this. It probably will cost about the same as a large checked bag.
As for the mode of travel, I believe ALL U.S. airlines have to honor Emotional Support Animal (ESA) papers, as well as foreign airlines as they travel to or from the U.S. The tricky part is if you are travelling between two countries that don't honor ESA. In these cases you must start your booking journey with the names of the handful of airlines that allow pets in the cabin. Among other rules that are different in foreign airlines is that they can only have a certain number of pets on each flight, so the airline has to be contacted directly about the specific flight in question to see if they will have room. Additionally, you typically need to have a pet carrier to store them under the seat rather than in your lap. ESA papers are available to you if you consider your pet to have majorly relieved you of diagnose mental ailments. Some people think you have to lie to get these papers, and that's really not true. If your pet brings you joy and love, then they elevate your mental state and diminish your anxiety. You can get ESA papers online through a variety of websites, for in the ballpark of $150 and an hour of your time. Once acquired, you need to fill out an additional form for the specific airline you are using. After you inform the airline you are travelling with an ESA they will provide you with a form that usually includes physical characteristics and basic info about your dog from his or her records.
Truth be told, the airline had the papers on file, but from start to finish throughout the flight with two legs and going through security twice, not once did anyone ask to see papers or question our dog's presence in any way. We got plenty of looks of envy though. Regardless, we had copies of every possible paper that could be relevant in plastic protector sleeves ready to deploy.
The only other things we did in preparation for the flight was update her dog tags to have our Whatsapp numbers and emails (in case people do not want to call international to report her lost), and bought her a dog-carrier sling for convenience in the airport. The carrier sling has a little pocket and a security latch, but we found she really liked being in the sling. We also got her a collapsible water bowl so that we could easily give her some water. But, the most important question dog owners may have about travelling long distance is "How do you keep them from having to go?" This is a delicate issue, and we were able to solve it with no problems on our 13 hour journey. We simply fed pup quite handsomely in the few days before travelling, and then fasted her starting about 12 hours before the flight until immediately after. Of course check with your vet and make sure this protocol would work for your dog, but if humans can fast for weeks, a one-day fast is okay for dogs and keeps them from having to use the bathroom. We gave her water and she was able to relieve herself a few times at the airports' pet relief areas. We also gave her some all-natural anxiety treats that had L-theainine. I haven't personally tried them, but these ones have a lot of the same ingredients! She slept a lot on the plane and was a very good pup!