スミソニアン国立動物園さんのインスタグラム写真 - (スミソニアン国立動物園Instagram)「We are sad to share that our elderly gray wolf, Crystal, was humanely euthanized April 21. On Sunday afternoon, American Trail keepers noticed that she was having difficulty breathing. Zoo veterinarians anesthetized Crystal and performed an exam and administered care to alleviate her symptoms. Because of her advanced age (14 years old) and the risk that a surgical procedure to help her breathe could predispose her to other medical issues, staff determined it would diminish her quality of life, and they elected to euthanize her. American Trail keepers fondly remember Crystal as playful, goofy and full of energy. When she was younger, she seemed to especially enjoy playing with enrichment items. Toys, puzzle feeders and other enrichment objects stimulate animals’ visual, tactile, olfactory and auditory senses, encouraging them to use their natural behaviors in novel ways and exercise choice and control over how they spend their time. Crystal’s favorite enrichment items were ones that required her natural hunting abilities. She seemed to especially enjoy pulling apart and destroying pillows as depicted in this photo. As she entered her golden years, Crystal’s overall activity level decreased, but every so often she would surprise keepers by actively tossing enrichment items around her yard. She served as a wonderful ambassador for her species, teaching Zoo staff and visitors about gray wolf biology, behavior and socialization. Learn more: https://s.si.edu/2Prkjps.」4月24日 2時42分