She was given the Hero Therapy Dog Award by the American Humane Hero Dog Awards in September 2018.
The Arizona Republic reported Chi Chi was diagnosed with cancer in March 2018.
"She has a very aggressive tumor in her nasal cavity," the family wrote on Facebook at the time. "The prognosis is not good."
The family had about 11 more months with Chi Chi before she died.
The Howells took to Facebook Tuesday to thank followers in a lengthy post for their support.
“Our family is very grateful for the outpouring of love and support we’ve received over the past 24 hours,” the family wrote. “Your messages and comments are a testament to Chi Chi’s impact worldwide during her short time with our family. Your memories and encouragement are very healing to us.”
The full message can be read below.