When the Beastie left Pupfessor Rex and his School for Gifted Dogs, he went and became a scientist. He spent his time Studying and looking into MUTT - ATION. He discovered a gene that could grant temporary Mutt - ant powers to any canine. He also discovered that someone was trying to steal his work, so he used the serum on himself to give him a disguise whilst he confronted the industrial spies. However, he was unable to reverse the process as he had found he had remained in his secondary Mutt-anted state too long.
At first he was all Grey and furry, but later he settled for a much nicer blue colour.
In the future he would return to Pupfessor Rex & the X - Mutts, but for now he found himself a home with the AVENGING HOUNDS
Tomorrow, its SCHOOLS OUT for the Class of 1963 AND WELCOME to the Class of 1975