A pit bull named Lucas, rehabilitated after being rescued in 1997 from being used in the dog fighting ring funded by quarterback Michael Vick, was euthanized due to health reasons.

Officials at the Best Friends Animal Society in Kanab, Utah, said Lucas, who was about 13 years old, was euthanized Wednesday because of accumulating health problems.

Almost two dozen of Vick's dogs that were rescued from the Bad Newz Kennels dog fighting operation that Vick paid for, were rehabilitated at Best Friends facility.

Lucas was one of two dogs not permitted to be adopted because of his history as a fighter.

So, the dog spent most of his time lounging in the administrative offices at Best Friends, where he was widely known as one of the friendliest dogs at the sanctuary.

Gregory Castle, the CEO at Best Friends, says it was "a blessing in every way to be around him and to witness the wonderful effects on everyone he met."

In April 2007, Vick, then playing for the Atlanta Falcons, was involved in an illegal dog fighting ring that he operated for five years. He pleaded guilty to federal felony charges and served 21 months in prison.

According to court papers in the cases of Vick and his co-defendants, Vick bankrolled the operation and, with others, killed dogs that did not perform well.

Vick was signed by the Philadelphia Eagles in 2009 after missing two seasons while in federal prison.

Since leaving prison in 2009, Vick has sought to rehabilitate his career and speak out against animal cruelty. He worked with The Humane Society of the United States defending animal rights.

He also made appearances at schools and spoke to students about the dangers of being involved in dogfighting.

Vick wrote a book that he was planning to market but has had to cancel appearances due to planned protests and threats to retailers.