Basically, when designing alien and fantasy races, I tend to try and figure out how they would sound. I originally figured that their language would be made of growls and barks, but then I realized that was too basic. Ask any linguist, and they'll probably tell you that there are no languages that are just merely basic. Every language in real life (and those that have been constructed, i.e. Klingon and Tolkein's Elvish languages) has some sort of complexity and uniqueness to it.
So, this all boils down to the question of how would the spoken language of a caninoid species sound like? Please note that I said spoken language, as I have already figured out that there would be a great deal of body language going on, since they would have tails and ears.