The RADIOACTIVE MUTT was one of the Original Mutt-Masters of Evil, who are themselves an evil version of the Avenging Hounds put together by BARON SNIFFO, the Woofzi war criminal.
But the Radioactive Mutt had been around for a long time before he teamed up with SNIFFO and his crew.
Dr CHUM LU was a Nuclear Physicist from what was then called The PUPPIES REPUBLIC OF CHINA. His Com-mutt-ist leaders ordered him to find a way to defeat the Dog of Thunder PAW, who had himself defeated the Chinese Army's attempt to invade INDIA.
Chum Lu exposed himself to radiation little by little until he finally gave himself a massive blast of lethal radiation. The result was he was able to absorb and release radiation. The down side was he ended up glowing green and was deadly to be around.
He did battle with the Dog of Thunder, but was defeated. He would try again and again over the years to beat PAW, but was always defeated.
He was chosen by Barron Sniffo to be part of his Mutt-Masters of EVIL as SNIFFO wanted each Vill-hound to be in some way connected to the Avenging Hounds. IE, Barron Sniffo was Canine America's foe...... The Melting Mutt, was Iron Hounds foe, The Evil Bark Knight. foe of Giant-Dawg and the Waspish Pooch..... and finally The Radioactive Mutt, foe of the Mutty PAW, Dog of THUNDER.
Here is the Radioactive Mutt as his evil best.
Tomorrow a time travelling mutt