Pet owners are now allowed — at least until February — to travel with their small dogs and cats on two northeastern lines, Amtrak announced Monday.

As part of a pilot program, pets weighing 20 pounds or fewer are allowed on trips up to seven hours, an Amtrak spokeswoman said. Pets are allowed on trains from Boston to New York, Washington D.C. and Lynchburg, Newport News and Norfolk in Virginia on the Northeast Regional service, and between Boston and Brunswick, Maine on Amtrak’s Downeaster route.

Chelsea Kopta, a spokeswoman for Amtrak, said owners must carry pets in a carrier and place them underneath their seats. She said the program, which calls for one pet per rider, follows another pilot that Amtrak launched in Illinois.

During the Illinois program, which began last year, more than 200 animals accompanied passengers on trains “without a single complaint or incident,” Kopta said in an e-mail message.

“We are always looking for ways to enhance the passenger experience,” she said.

Owners will be charged $25 to travel with their furry friends, an Amtrak press release said. Pets must be at least eight weeks old, odorless and harmless, not disruptive and require no attention during travel, according to a release. The release said pets are not permitted in business class, cafe cars or other food service cars.

Ben Gran, a blogger and former pet owner, said the restrictions and size requirements for Amtrak’s pet traveling program are encouraging for travelers who aren’t necessarily fans of animals.

“People have the right to own pets, but people who don’t own pets have the right not to be bothered by other people’s pets,” said Gran, who wrote a post about how he hates dogs.

Laura Nativo, a dog trainer who spoke before Congress in 2013 to advocate for pets on trains, said Amtrak’s move is a “paw print in the right direction.”

“Pets are part of the family and I can’t imagine not being able to travel with my dog,” said Nativo, who admits she used to sneak her now 13-year-old Pomeranian, Preston Casanova, onto planes by disguising him as a sweater in her purse. “We allow screaming babies — if [the pets] are well-socialized and well-mannered, those dogs [and cats] deserve the same privilege to travel that children do.”

Owners traveling with pets must check in at the station ticket office no later than 30 minutes before the train departs to confirm their pet’s eligibility and sign an agreement, according to an Amtrak press release.

The program, which began Monday, ends February 16. At the end of the program, Kopta said Amtrak officials will decide whether to extend or expand the program to other train routes across the country.