Which animal has the longest canines?

Canine teeth began with a group of land vertebrates called therapsids. Also known as mammal-like reptiles, they were the evolutionary precursors to mammals. The first true mammals inherited this trait and passed it on to their descendants, so all mammals that have teeth (with very few exceptions, like dolphins) still retain canine teeth even though they no longer use them for their original function. Horses, bovine, and other herbivorous mammals all still have significantly diminished canine teeth as do omnivorous mammals like bears, raccoons, and humans.
Wolves, coyotes, hyenas, jackals, African wild dogs, dingos, dog/wolf and dog/coyote hybrids, and domestic dogs. That's all I can think of off the top of my head.