The Centers for Disease Control and Prevention is implementing new rules for international travelers and their dogs to prevent the spread of rabies.

Now, all dogs entering the United States must be at least six months old, have a microchip and look healthy. These new rules went into effect on Aug. 1.

If you are traveling to a country the CDC considers low risk for rabies, like Mexico, you have to fill out a dog importation form, even if you are traveling by car.

The form asks for your name and your dog's info, like their breed and color. You will then show the receipt to Customs and Border Protection officers at the ports of entry when you cross back into the U.S.

For a full list of requirements, click here.

There are additional requirements if you're traveling to a country that is high risk for rabies. For a list of high risk countries for rabies, click here.

"As soon as you come in, if there is a dog in the vehicle, the officer will ask 'hey do you have your CDC form?' and all you have to do is produce it, and you're good to go," Hidalgo, Pharr and Anzalduas Bridge Supervisory CBP Officer Francisco Rodriguez said.

If you are not able to show the form, a CBP officer will contact a local CDC representative for further guidance.

To find the dog importation form and a list of instructions on how to fill it out, click here.