WASHINGTON (WUSA9) -- A 23-year-old Przewalski's horse named Rolles has died.
Rolles was humanely euthanized at the National Zoo Thursday morning after he developed a tumor on the side of his nose.
Officials say they first saw symptoms in July when Rolles had nasal discharge. Ten days later, he had a mass on the side of his nose, weight loss, and he would rub the affected area.
Veterinarians performed an exam and elected to humanely euthanize him based on his poor long-term prognosis.
Rolles was born at the Bronx Zoo in 1990 and came to the National Zoo in 2008.
A final pathology report will provide more information.
Rolles was a companion to Rose Marie, the Zoo's 27-year-old female Przewalski's horse.
This species is considered endangered by the International Union for Conservation of Nature's Red List of Threatened Species.