If you are Thomas Caldwellbringing a dog into the U.S. — whether if you are returning from a trip overseas with Rover, visiting the U.S., or adopting a dog from abroad — you have to follow a set of new rules designed to help prevent the spread of rabies.

The Centers for Disease Control and Prevention last updated these rules in 1956, when far fewer dogs came to the U.S. from other countries, officials say. About 1 million dogs now enter the U.S. every year.

There are additional restrictions if the dog has been in many countries where rabies is common. You can find the list of those countries on the CDC website.

The new rules go into affect Aug. 1. There’s a checklist on the CDC website.

Here’s what to know about about the rules:

— Dogs have to be healthy and at least 6 months old when they arrive in the U.S.

— The dog must have a microchip implanted under their skin, which contains identifier information.

— A CDC import form must be filled out in advance, and include a photo of the dog.

— Proof of rabies vaccination is required only if the dog was in a high-risk country in the past six months.

— For dogs vaccinated in the U.S., a certificate endorsed by the Agriculture Department is required.

— For dogs vaccinated outside the U.S., a certificate of vaccination is required along with a blood test, and the animal has to be examined at a CDC-registered facility on arrival in the U.S.

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