Some English verbs
work with both 0 and 1 objects
if 0 objects are specified, the meaning is the subject did, or appeared to do, the activity to him/her/itself, or "something made" the subject do the activity
The impact was such that the canine flung into the air and fell into a drain five meters away.
This is equivalent to saying "The impact made the canine fling into the air."
Saying "The impact flung the canine into the air" is also OK.
Verbs that don't work like this require passive voice, and you could still use passive voice here if you wanted as well.
The impact was such that the canine was flung into the air and fell into a drain five meters away.