I saw the movie when it debuted in 1978 and was nine years old at the time...The violence and moments of mortality of the rabbits, no doubt, left me wide eyed but I did not experience any significant trauma from it.
I read the book in 1989 at age 20 and it was an incredible novel...If presently properly to children 9-15 years old, I think it would be a very special experience for them...