Kelso was a German Shepherd dog. He was the dog of Professor Frederick Marius. He had amber eyes.
Marius loved his dog and often spoke to him. When he had problems, he would always go to Kelso to have a word with him. Even though Kelso never answered him, talking to him helped Marius. (PROSE: One Man and His Dog)
When Marius wanted to work for the Bi-Al Foundation, he had to leave Kelso behind. Since Marius loved Kelso so much he created K9 Mark I, a robot dog, which he was able to take to his new work place. (TV: The Invisible Enemy)
Kelso stayed with Grace, who looked after Kelso from then on. (PROSE: One Man and His Dog)