Naruto Episode 45: Surprise Attack! Naruto`s Secret Weapon!
Episode 45 of 220 of Naruto, aired August 13, 2003, 25 minutes. Available with English subtitles and dub where released.
Episode summary
The battle between Naruto and Kiba draws to a close, with each of them giving it everything they've got. After being tricked by Naruto, Kiba can no longer rely on Akamaru's help. Naruto decides now is the time to release his new jutsu, only Kiba won't give him time to prepare it!