In an Elseworld reality where Superman was the son of astrophysicist Jonathan Kent, sent off into space when a meteor threatened to annihilate Earth and crash landing on Krypton, where he was raised by Jor-El and Lara, the human "Kal-El" didn't get a dog. Instead, he's assigned his very own robot named Krypto. Silver rather than gold like his adoptive parents' Kelex, he accompanies the young Kal everywhere to make sure he doesn't get into trouble and his exoskeleton doesn't break down and leave him suffering in Krypton's higher gravity.
After Kal-El becomes Green Lantern of his sector, Krypto isn't really needed anymore. Read more about GL Superman's story HERE. His robotic best friend does not appear in the sequel, Last Stand of Krypton.
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