canine / k9 are similar-sounding terms with different meanings (referred to as homophones). To better understand the differences, see below for definitions, pronunciation guides, and example sentences using each term. 👇
canine: (noun) one of the four pointed conical teeth (two in each jaw) located between the incisors and the premolars. (noun) any of various fissiped mammals with nonretractile claws and typically long muzzles. (adjective) of or relating to a pointed conical tooth. (adjective) of or relating to or characteristic of members of the family Canidae.
k9: NA
canine: k·EY·n·AY·n
k9: NA
(Examples are Wikipedia snippets under the CC ShareAlike 3.0 license. Definitions drawn from WordNet.)