A much-loved polar bear has been diagnosed with an incurable condition which could lead to her being put down.

Mercedes, who lives at the Highland Wildlife Park near Kingussie, a small town in the Highland region of Scotland, has advanced osteoarthritis.

She is being treated with painkillers and other medication, but the park said it may have to consider humane euthanasia in the future if her condition deteriorates further.

The 30-year-old bear was moved to a new enclosure at the park in autumn 2009 from Edinburgh Zoo.

Simon Girling, a vet for the Royal Zoological Society of Scotland, which runs the park, said: “Mercedes suffers from advanced osteoarthritis, for which there is unfortunately no cure. Her condition became apparent some time after her move to the Highland Wildlife Park from Edinburgh Zoo.

“This condition is seen in most elderly polar bears both in the wild and in captivity. We’re managing her condition with various medication and pain relief, and we’re currently trying her on some new medication.

“If Mercedes deteriorates further in the future and begins to suffer, it is probable that with sadness we will have to consider humane euthanasia on the grounds of health and welfare. However, we are not at this stage yet.”

The polar bear was rescued from her native Canada and brought to Scotland after she was scheduled to be shot because she had begun roaming into town in search of food.

Her move north from Edinburgh came after £50,000 for the project was secured following a public appeal.

Polar bears in the wild live 18 to 20 years on average, and 25 to 29 years in captivity.

Douglas Richardson, animal collection manager at the Highland Wildlife Park, said: “Mercedes is 30 years old, which is extremely old for a polar bear, and it is to be expected that her health may be deteriorating.

“Despite her mobility and joints not being what they once were, Mercedes still currently enjoys a good quality of life here at the Highland Wildlife Park, where she has been for almost two years now. We constantly liaise closely with both our internal vet team and external experts and our team of keepers are on hand to give her all the care she needs.”

He added: “If you have a dog or cat that’s 15 years old you have to start looking at it more carefully and thinking they are at that age where lots of diseases and health problems can arise, and that’s exactly where we are with Mercedes.”

He said 30 years for a polar bear is like 90 years for a human.

In November, Mercedes was joined by polar bear Walker who arrived in Scotland after being transferred from a zoo in Holland.

The pair’s relationship got off to a tense start but she now appears to have accepted the new arrival.