(CNN) — It isn't just human beings who need a passport in order to travel.
Fashion designer Valentino had a coterie of six adorable pugs who traveled with him on his private jet. Not only did they all have passports, but odds are they had more stamps than the average human traveler.
However, most of the time "pet passport" is more of a metaphorical term. Rather than blue or red booklets with names and photos in them, pet passports are more likely to be a stack of paperwork.
And while one passport may get a human into multiple countries, the requirements for animals to travel vary widely between continents and countries. The process can be expensive and overwhelming, but it is navigable.
Beth Schutte is the president and CEO of the ARK Import Export Center, which manages The ARK at JFK, a full service animal reception and quarantine center located right on the runway at New York City's JFK airport.
"The European Union primarily pioneered this whole pet passport practice that enables animals to move more freely with their owners throughout the European Union and the UK," Schutte explains.
"Countries like Russia or China, you would see pet passports, but they really aren't an official document, like a human passport. It's more a consolidation of all the pet information. The United States does not require the pet passport at all."
No matter your country of origin and your country of travel or relocation, there is essentially one piece of advice that every pet travel expert agrees upon: get started as early as possible.
Dog trainer and author Bash Dibra, who has worked with the furry friends of celebrities like Mariah Carey and Sarah Jessica Parker, believes it's never too soon to get your pet more comfortable with traveling, even for short distances.
"Basically, the first time you get your dog you should be getting it ready for imaginary trips you will be doing," he says. "Crate training gets you into proper training for everything else."
He adds: "Once a dog or cat is crate trained they enjoy being in the environment. You can do that by planning special trips, go in the car, or to a weekend house or visit friends, or even if you want to take your dog to a hotel."
Schutte recommends working with a reputable travel agency that specializes in animal transport -- some of those can be found by checking out IPATA's list of approved companies.
Meanwhile, Dibra advises that an overwhelmed owner reach out to their local chapter of the Society for Prevention of Cruelty to Animals (SPCA) for a vet recommendation if they don't know where to start.
You should also see if your current veterinarian is familiar with the rules for travel and consider one or two visits to another vet if that's not the case.
Schutte and her colleagues have seen pets denied boarding for all kinds of minor reasons, like transposing two numbers in a date. In the United States, dates are written month first, while in many other countries they are written day first and month second, so "May 10" in the US becomes "October 5" in France.
To reduce panic for both the human and the animal, working with someone who is familiar with the latest paperwork and restrictions will help reduce stress and make sure everything is in order on the big day.
In the United States
Animal transport into the United States is the domain of the Department of Agriculture's Animal and Plant Health Inspection Service, more commonly referred to by its acronym APHIS.
The Department defines "pets" as dogs, cats, rabbits, ferrets, hedgehogs and most categories of reptiles, amphibians and rodents. These animals must be owned by a private individual and not intended for science experiments or resale. There is one major exception to the pet guidelines. If you have a pet bird, you'll need to provide additional information to a veterinarian stationed at an approved port. The Department of Fish and Wildlife may need to be involved as well. More details here. APHIS' website has helpful information about transporting animals in and out of the country as well as between states and territories, since places like Hawaii and Puerto Rico have tighter regulations.
There are occasional exceptions to the rules in cases of emergency -- for example, right now, animals being brought from Ukraine can get their paperwork in order more quickly due to the situation there.
The Transportation Security Administration (TSA) has specific guidelines for animals traveling by plane -- check out their extremely cute, gif-filled guide for more.
In the European Union
One of the perks of the European Union is that travel is fairly easy for humans and their pets within those countries.
The single best thing you can do is to make sure your pet -- defined in the EU as a dog, cat or ferret -- is up to date on rabies vaccines, and keep that paperwork with you just in case when you cross a border.
European Union pet passports can only be issued by approved vets in EU member countries. Ones from the UK, US or other nations will not be accepted.
Any pet going from a foreign country into the EU must be microchipped, vaccinated against rabies and over the age of 12 weeks.
If you're coming from the United States, you will need to fill out the Annex II form issued by APHIS.
Individual airlines have different policies about whether pets can travel in the cabin with their owners or not -- size and breed play a major role. Make sure to do your research before booking tickets.
This dog is having a pre-departure nap.
In the UK
Thanks to Brexit meaning the United Kingdom is no longer part of the European Union, there are now different requirements for bringing a pet into the country. These rules apply to England, Scotland and Wales and not to Northern Ireland, which has its own policies outlined here.
Cats, dogs and ferrets traveling as pets to the UK must be microchipped, vaccinated against rabies and have a valid pet "passport" or health certificate. It's also a good idea to give dogs tapeworm treatments ahead of traveling.
Beyond that, certain breeds of dogs -- like pit bulls and Japanese tosas -- are banned entirely.
Because it's an island, the UK enforces its animal transport rules strictly. Failure to fill out paperwork correctly or bring relevant documents could result in your pet being refused boarding, being seized upon arrival and/or forced to spend up to four months in quarantine.
Follow the British government's guidelines closely -- you can see them here.
The UK is also currently expediting the process for pets being transported from Ukraine.
In Australia, the Department of Agriculture, Water and the Environment (DAWE) handles animal travel criteria. First, all nations are placed into one of three groups.
The first two groups mostly consist of nearby countries and Pacific islands, while group three is where you'll find most EU member nations, many Caribbean islands, Canada and the United States.
Cats and dogs -- no other animals -- from approved countries may be brought in as pets, but they will be subject to a 10-day quarantine in the Mickleham Post Entry Quarantine Facility in Melbourne.
Simply arriving in the country won't be enough. You'll need to secure a booking for your pet at Mickleham and pay the fees necessary to care for your pet. This begins with an import fee of $1,200 AUS (US$894).
Quarantine protocols are very strict. As tempting as it may be to send your dog or cat to Mickleham with a favorite chew toy. these will all be destroyed upon arrival due to possible contamination concerns. Food is also selected by the facility, so if your pet has specific needs make sure to notify Mickleham in advance.
If your country is not on the list of approved nations, you'll need to organize transport via a third country.
If you're in the continental U.S., it is fairly easy to travel with your pet by car.
Past the paperwork
Even if your pet doesn't need a "passport" right this minute, you can start thinking ahead by buying or organizing things you'll need later.
Dog trainer Dibra prefers crates for most dogs, although smaller dogs who are able to fly in the cabin (or in the backseat of the car) with their owners can be placed in smaller carriers. When it comes to cats, he recommends plastic carriers, which he says are "sturdier and safer," especially in emergencies.
Our partners at CNN Underscored have put together a list of the best brands of pet carriers for travel.
In addition to buying new things, you should also hold on to old ones. Favorite toys and snacks are a must for travel, and many animals are comforted by a familiar-smelling item like a stuffed animal or an owner's T-shirt inside their carrier.