They probably do raise their young but only up to a certain point (who would want to look after a teenage dragon?) because it doesn't look like there is much socialization happening (that's for ponies), but do seem to recognize family ties (You know, Crackle's cousin).
Adult dragons appear to be solitary and extremely territorial, which is pretty much how they are portrayed in western culture. They don't want other dragons (or any thing else) messing with their stuff. I think that would extend to another dragon's young, but they would tolerate their own, if only to keep the bloodline going.