In 1998, the major DC comics TV shows and films that would have had merchandise tie-ins would be "Superman: The Animated Series", "Batman: The Animated Series", "Batman Beyond", "Static Shock" or "Batman & Robin"- but I don't think it's from that movie. More than likely one of the cartoons I mentioned- I would guess you may be on the right track with Ace, the Bat-Hound. It could also possibly be one of The Joker's hounds, as I seem to recall him having dogs along with Harley Quinn's hyenas, but I could be wrong.
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