PROVIDENCE — Most dog and cat owners probably don’t question their veterinarian when the doctor tells them it’s time for their pet to get a vaccination for rabies — one of a very few diseases that can be transmitted from animals to humans.

But Cindy Larson, of Barrington, had a lot of questions when, six years ago, her kitten got his first rabies shot, promptly spiked a high fever and required oxygen to breathe.

Another fever, and severe swelling of the leg, followed a rabies injection two years ago, Larson said. Thankfully, she said, her cat fully recovered from both terrifying episodes.

One of the things Larson learned in the aftermath is that Rhode Island requires rabies vaccinations for pets more frequently than is medically warranted.

That is about to change, according to the state veterinarian.

Since 1996, pet owners in Rhode Island have been paying for rabies shots once every two years, in accordance with regulations adopted by the state Department of Environmental Management.

But the scientific data on the most commonly used brands of rabies vaccines show they protect dogs and cats for three years — at a minimum.

New rules, expected to go into effect about March 16, change the mandatory vaccination period from two to three years.

In the meantime, the state veterinarian, Dr. Scott Marshall, has created a transitional policy so that pets now protected aren’t reimmunized unnecessarily just because the old regulations have not yet expired.

Marshall chairs the state Rabies Control Board, which is nearing the end of a regulatory procedure that began last April.

“The consensus was that yes, we should get more in line with current thinking,” Marshall said, and “allow for the duration of immunity to reflect what the product label said.”

The only other state with a mandatory two-year time span is West Virginia, which is also moving to change to three years.

The board had been approached by pet owners alerted by the Rabies Challenge Fund, an organization created by a Maine woman whose golden retriever developed a cancerous tumor on the site of a rabies vaccine injection in 2004.

Marshall said that life-threatening adverse reactions to rabies vaccines are extremely rare in animals.

But when they do occur, they can have a lasting and profound impact.

Marshall said the two-year span between vaccinations was intended to ensure that there was a “buffer period” in case a pet owner allowed a rabies vaccine certificate to expire. The thinking was that the animal would still be protected, even though the vaccines were technically not up to date, he said.

But Marshall, who has been the state vet for about three years, acknowledged that there is no science supporting a two-year interval.

Wendy Waller, dog owner and lawyer for Save The Bay, volunteered to rewrite the regulations and submit the revisions to the Rabies Control Board. She said she didn’t want to see the regulatory process languish “for lack of resources.”

And yet 10 months have elapsed since last April, when the Rabies Control Board agreed in principle to the change, while the new language received initial approval and legal, environmental, and fiscal impacts were reviewed – all standard operating procedure.

Still to come is a public hearing on March 4 at 9 a.m. in Room 300 of DEM’s main office at 235 Promenade St.

In the meantime, the seven-member Rabies Control Board will also discuss the regulations Monday at 9:30 a.m. in Room 370 at DEM.

gmacris@projo.com