RACINE, Wis. (CBS 58) -- The Racine Zoo is mourning the loss of one of their beloved animals. They announced Naka, the zoo's resident Amur tiger, passed away last week at the age of 18. 

According to a news release, Naka had recently been diagnosed with a malignant sarcoma that was discovered during routine behavioral husbandry training. Test results showed the lump was an aggressive form of cancer. 

Naka underwent a procedure to have the mass removed and though successful, Naka was not able to make a full recovery and passed due to complications from the surgery. 

With an average life span of 10 to 12 years in the wild, the zoo says Naka had way surpassed her wild counterparts being only a little over a month shy of her 19th birthday. Naka was one of the oldest Amur tigers in North American zoos. She has one surviving brother, Kunali, at the Alaska Zoo in Anchorage, Alaska. 

Naka was born at the Rosamond Gifford Zoo in New York on June 7th, 2004. Naka was sent to the Racine Zoo from Beardsley Zoo in Connecticut in 2016 as a recommendation from the Amur Tiger Species Survival Plan. As an Amur tiger, Naka was one of the most critically endangered species (less than 500 remaining in the wild) and the largest cat species.