A week after being put on hospice care, the Denver Zoo's beloved Dolly has passed away.

Dolly had been battling health problems and was being given pain medication to feel comfortable for the last week, 9NEWS reports. On Friday, she was humanely put to sleep.

"Dolly will be remembered as one of the 'sweetest and most trusting' animals that was always 'young at heart,'" the Denver Zoo wrote in a Facebook post.

It's believed Dolly was one of the oldest elephants in captivity, and is reportedly the tenth oldest elephant in a North American zoo. At 52 years of age, Dolly surpassed the average life expectancy for female Asian elephants in captivity, which is 46.9 years.

Rest in peace, Dolly!