How did Marley die at the end of Marley and Me?

At the end of "Marley and Me," Marley dies due to complications related to his age and health issues. He experiences a decline in his condition, suffering from severe Arthritis and gastrointestinal problems. The family is faced with the difficult decision to euthanize him to prevent further suffering, which they do while surrounded by love and comfort in his final moments. This poignant moment highlights the deep bond between Marley and his family.