Two US agencies check your dog at the border, and each asks for something different. What each one wants, the order to get it in, and why cats are a different story.
Crossing into the United States with your dog used to be a formality almost nobody prepared for. Not any more.
The rules for bringing dogs in changed in 2024, and since 2025 there has been an extra requirement for dogs coming from Mexico. Both are checked at entry, by air and by land, and in June 2026 the border authority reminded travellers that it would enforce them strictly — including for US dogs coming home from a trip.
None of this is hard. But it's something you prepare weeks ahead, not the night before.
Sources last checked: October 11, 2026. These rules change. If this article and the official page disagree, the official page wins.
There are two agencies, and it's worth not mixing them up:
The CDC (Centers for Disease Control and Prevention) handles rabies. Its rules depend on the country you're coming from, and Mexico is on the low-risk list, which makes everything simpler.
The USDA, through APHIS, handles screwworm. Since July 2025, dogs coming from an affected region — and Mexico is one — need a specific certificate.
Both are checked at the port of entry. Meeting one doesn't cover the other.
For a dog coming from Mexico, the CDC asks for four things:
1. That the dog has been only in low-risk countries for the past six months. If it visited a high-risk country in that time, different and much stricter rules apply. For the vast majority of dogs living in Mexico, this is already met.
2. A minimum age of six months on arrival. It's an entry requirement, not care advice — but it's the one that cancels the most family trips with a puppy.
3. A microchip that a universal scanner can read. If your dog already has one, ask your clinic to scan it and confirm the number before the trip: you'll need it for the form.
4. The receipt for the CDC Dog Import Form. It's the only document the CDC requires:
The dog also has to look healthy on arrival. It may be inspected.
Which vaccines your dog needs is a different conversation, and it's not with the CDC: it's with your vet.
This is the requirement most people don't know about, because it's recent.
Since July 9, 2025, every dog entering the United States from Mexico must carry a certificate stating that a vet examined it within the five days before travel and found it free of screwworm — or that it was treated and isolated until it was.
Three practical points:
In June 2026, CBP — US Customs and Border Protection — reminded travellers that this certificate applies to every dog entering from Mexico, including US dogs returning from holiday.
The rules are the same. The CDC and USDA make no distinction between an airport and a border bridge: the paperwork is checked the same way.
What changes by air is that the airline's rules apply as well: cabin or hold, carrier dimensions, breeds they won't accept. We cover that in flying with your dog inside Mexico and in cabin or cargo — the five questions work just as well for an international flight.
By land there's no airline, but there is a queue. Have the papers in a folder, in your hand, before you reach the booth.
Much simpler. Neither the CDC nor the USDA requires specific documents for pet cats: they just need to look healthy on arrival, and may be inspected.
But note: the airline and the state you're going to may ask for more. Check both before you travel.
SENASICA publishes its own guide to travelling abroad with a pet. Check it the week you travel, because it's the source that confirms what Mexico asks of you on the way out. What is clear is that the screwworm certificate is signed by a SENASICA-authorised vet, so that step happens on this side of the border.
A trip is when you find out whether your pet's history exists outside your memory. In Maskotis you can keep their details — including the microchip number — and their dated care events, and print their sheet to carry in the folder with the rest of the papers. Why paper still matters at a counter, we explain here.
If the trip has a date: start with the microchip. Everything else depends on that number.
Checked October 11, 2026. Always confirm on the official page before travelling:
Maskotis does not give medical advice and this article is not a substitute for a veterinary consultation. The requirements described here are set by US and Mexican authorities; what your pet needs, and when, is decided by someone who can examine them. Take it to your trusted vet, or to the nearest clinic — they'll help you there.
It isn't a fight with an obvious winner. Paper wins at the counter; the app wins in month fourteen, when nobody remembers. The honest thing is knowing when each one wins.
You walk out with a full head and ten minutes later half of it is gone. The six things worth writing before you start the car, and the questions that make sure there's something to write.
It sounds like a step backwards and it isn't. There are four specific moments where paper wins, which is why printing is part of the product rather than an accessory.
