Inuka the polar bear may be 'elderly' but he's still young at heart
It is hard for it to get up in the morning, so it has a special elevated bed which it can just slide off easily.
It also has arthritis and has to take painkillers every day.
The male, Singapore-born polar bear turns 26 today, but that means it is in its 70s in human years.
Inuka suffers from age-related conditions such as arthritis and dental issues.
"There's stiffness when he gets up in the morning and he faces difficulty walking, sitting or rising.
"It can be very painful, especially because he's heavy," said senior keeper of carnivores at the Singapore Zoo, Mr Mohan Ponichamy, 39.
Polar bears are the largest land carnivore in the world, and Inuka weighs 505kg. The weight makes its arthritis more painful, and affects how it moves.
Bears are intelligent creatures. We talk to him and he’ll sit or lay down and listen to us.Mr Mohan Ponichamy, senior keeper of carnivores at the Singapore Zoo
It was diagnosed with arthritis three years ago.
The keepers monitor its weight and have adjusted its diet to ensure its weight is maintained as close as possible to an optimal 520kg, to help its joints.
Inuka is on long-term glucosamine and anti-inflammatory treatment for its arthritis.
Mr Ponichamy may have only been Inuka's keeper since June, but he has developed a trove of fond memories with the animal.
"His relationship with keepers is very unique, because he grew up with keepers' presence his whole life.
"He wants our attention all the time," he told The New Paper.
"Bears are intelligent creatures. We talk to him and he'll sit or lay down and listen to us."
Mr Ponichamy mentioned that Inuka, despite its age, is young and playful at heart.
"Although we'll buy many expensive toys for him, his favourite toy will always remain his old rubber tyre.
"He brings it up the slope (in the enclosure), lets it roll down and watches it roll," he said.
"What he did next really surprised us. He walked back down, picked it up, went up the slope and did it again.
"Every now and then he'll also throw it into the water, wrestle with it and poke his head into the tyre."
Unfortunately, the extent to which Inuka can play is now limited due to its declining health as a result of old age.
Mr Ponichamy said: "Inuka knows he can't be as fast as before, so he's less playful now."
Inuka has an elevated bed, called a firehose bed, so it does not have to exert too much strength to stand up in the morning. It can simply slide off.
"He's showing all these signs of arthritis and he's slower than usual, but we can't tell (how severe it is).
"If it was very serious, he would not be able to move and eat," Mr Ponichamy said.
If Inuka's health worsens, the zoo will have to put it down.
Singapore Press Holdings (SPH) has supported Inuka's upkeep since its birth on Dec 26, 1990.
SPH Foundation, the charity arm of SPH, took over in 2007.
Celebrations for Inuka's birthday started last Thursday with a series of celebratory activities laid out for him.
Guests at Singapore Zoo can catch Inuka exploring its ice cave for treats, or watch Inuka's last special birthday enrichment session, which is special training older animals, at 10.25am today.