The tiny two-faced tabby cat much loved by social media users for her unusual features died on Friday (Dec 29).

Bettie Bee, who was born in a South African home with two faces, two noses, two mouths and three eyes, had developed pneumonia two days ago.

The female feline belonged to a litter of two other normal kittens, born 16 days ago on Dec 12.

Soon after its birth, it was brought to a rescuer who has experience in caring for cats with special needs.

"Bettie Bee is an angel now. I took her to the vet to let her go peacefully. I'm shattered," said the rescuer, who broke the news on Friday afternoon on a Facebook page dedicated to documenting the kitten's progress.

The rescuer, who wished to remain anonymous, said that Bettie Bee "was doing great until two days ago", when it was struck with pneumonia caused by milk entering its lungs.

It was treated immediately, and just when things were looking up, it vomited - likely due to nausea from the antibiotics or mucus - and "got more milk in her lungs", the rescuer said.

The rescuer said: "She was struggling and I said to myself from the beginning I would not let her suffer.

"For 16 days, I gave my all and so did she, I would do it all over again. She deserved to have a chance at life, but sadly it was not meant to be."

Within two hours, the post received over 1,200 comments and 200 shares, with many people expressing sadness at the kitten's death.

Some took comfort in the fact that it had fought a good fight.

Said Facebook user Taryn Leigh Brown: "This little soul really touched the hearts of so many. She was a real tiger among cats."

Felines with such facial deformities are better known as Janus cats, named after the Roman god of the same name, who is usually portrayed as having two faces.

They have an extremely rare congenital disorder known as craniofacial duplication, and generally do not live very long because of health problems related to their condition.

In the post, the rescuer thanked those who had followed Bettie Bee's journey on the Facebook page for their love, kind words and encouragement.

The rescuer added that the page will be closed down "in a day or two". As of Friday, the page has more than 43,940 likes.