11/16/2011 02:08 pm ET Updated Nov 16, 2011

Denver Zoo Forced To Euthanize 9th Oldest Black Rhino In The World Due To Health Issues (VIDEO)

A 28-year-old endangered black rhinoceros named George was euthanized at the Denver Zoo on Tuesday after suffering from a variety of health problems, Fox31 reports. George was the ninth-oldest black rhino in captivity in the world and had lived at the Denver Zoo since 1984.

According to 9News, zookeepers had been monitoring George for some time for various health issues including diverticulitis, chronic diarrhea and continued weight loss. The Denver Zoo staff ultimately made the difficult decision to euthanize him Tuesday morning when he was found unable to stand in his indoor habitat -- the necropsy revealed that he had a ruptured spleen, The Denver Post reports.

George's death comes less than a week after the International Union for Conservation of Nature declared the Western Black Rhino of Africa officially extinct.

According to the Denver Zoo, as recently as 1970 there were an estimated 100,000 black rhinos worldwide, but those numbers have drastically dwindled to approximately 3,700 today. There are less than 90 black rhinos in North American zoos so the loss is felt deeply by among anyone who supports their conservation, 7News reports.

Slow reproductive rates as well as poaching of the black rhino horn for traditional herbal remedies and use as a dagger handle in some countries has pushed the animal to the brink.