That's not an empty statement, either. One of the things profilers look for in serial killer cases is childhood abuse of animals to help identify suspects. There is a strong correlation. I think that's even written up in the Crime Classification Manual (don't have my copy on hand).
One of the things I heard in a lecture last year was that when the NYS Humane Law Enforcement agents go to a house and investigate an allegation of animal cruelty, It's a safe bet that there are other forms of abuse going on- Either a battered wife or child abuse.
Watch "Animal Precinct" on the Animal Planet.
Agent Anne-Marie Lucas... Ahhh.