The world's oldest Janus cat — a feline with two faces — has died. Frank and Louie, a Guinness World Record holder, died this morning at the age of 15, owner Martha "Marty" Stevens said.

WORCESTER — The world's oldest Janus cat — a feline with two faces — has died.

Frank and Louie, a Guinness World Record holder, passed away at the Cummings School of Veterinary Medicine at Tuft's University in Grafton on Thursday morning at the age of 15 years, owner Martha "Marty" Stevens of Worcester said.

Ms. Stevens said Frank and Louie had been "a little down" around Thanksgiving and she was administering some fluids, but Thursday morning it appeared the cat was getting sicker and she raced to Tufts.

As she was pulling together a funding plan for the cat's medical care, the clinic called and told her Frank and Louie was critically ill. When she arrived, the cat was euthanized after veterinarians told her he was probably suffering from a "really bad cancer."

While she is devastated, Ms. Stevens said she knows the cat initially had no chance at all after being brought into the clinic to be put to sleep in September of 1999. Janus cats typically don't live more than a few days and are often rejected by their mothers. As word of the oddity spread through Tufts, Ms. Stevens and many other staff came by to have a look.

"I said, 'Can I try to save him?' " she said, adding that the veterinarians warned her that she would probably fail and the cat would die within three or four days.

"But the next day I came in with him, and the next day, and we started thinking he was going to survive," she said. "I tube-fed him until he was 3 months old because I was afraid he wouldn't be able to eat.

But Frank and Louie — or rather Frank because his side had the esophagus — learned to eat and thrived. The cat rubbed against legs and won over the hearts of many who thought he was difficult to look at. He had two functioning eyes and a center eye, which was blind. Two noses and two mouths but just one brain. All in all, he was a healthy cat, his biggest ordeals having been neutering and the removal of some teeth from Louie's mouth, which had no bottom jaw.

When the cat reached the age of 12, the Guinness people came calling, declaring Frank and Louie the oldest living Janus cat in the world. Ms. Stevens said she has a certificate and once saw Frank and Louie on Animal Planet as she was flipping channels. The cat had become quite famous.

Ms. Stevens said that most of the other Janus cats she's read about died very young. She spoke at length in 2013 to a family in Oregon that had a Janus kitten, but that kitten succumbed in two days. The kittens often have cleft palates or other deformities that make it difficult for them to get enough nourishment, but the tube-feeding seemed to help.

While she's reeling from the unexpected death of Frank and Louie, she said she'd do it all again and would take a Janus cat in if one was in need, though she knows just how rare they are.

"I would love to do it again," she said.

Contact Kim Ring at kim.ring@telegram.com.