[lazerwalker]

Yes, but dogs are domesticated animals we enjoy keeping as pets, not untamed wild animals we're discussing releasing into natural environments.

[chimeracoder]

Also, while some dog breeds are indeed endangered (or newly extinct) on the verge of extinction[1], many are dramatically overpopulated beyond sustainable proportions.

[1] http://en.wikipedia.org/wiki/Tahltan_Bear_Dog [2] http://en.wikipedia.org/wiki/Category:Extinct_dog_breeds