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Tuna the Chiweenie might be most recognizable for his pronounced overbite. When his owner, Courtney Dasher, started his Instagram account she was hoping that the pup would brighten someone's day but now he has a loyal following of over 2.1 million Instagram followers. His doggy empire also includes The Traveling Tuna, a blog advising the best pet-friendly hotels, and a book, Tuna Melts My Heart: The Underdog with the Overbite.