I have always said - punish the deed not the breed.
Yes, I think that you should have researched the breed very well before you got him, though you said you didn't know what breed he was... but once you found out maybe you should have gone back to the breeder, sometimes a breeder will take the puppy back depending on the circumstances.
However, I don't think whatever breed he is should be to blame for any behavior, its like when people say things about boxers or pitbulls, these are the most loyal and sweetest dogs, however people have labeled them as fearful animals, because of some owners that probably did a lot of things wrong. - I am not saying you have, just making a point -
I would say find a good trainer and take him in immediately, I am sure there is a lot of good trainers in winnipeg, you just gotta look, maybe if you go back to the breeder she can recommend someone too. I believe that many problems could be solved with the proper training, and unfortunately because of the lack off, many poor dogs end up in shelters.
Also, I am guessing you don't have a fence? or did he jump the fence? I know in the city here you cannot have a dog unleashed outside if there is no fence, you could be fined.
Dogs don't need to talk, their life is their message ~ unknown.
"The greatness of a nation and its moral progress can be judged by the way its animals are treated." ~ Mahatma Gandhi