Is there a connection between violence toward animals & violence toward humans?

Robert Lewis Dear, a 57-year old man from South Carolina, shot and killed several people at a Planned Parenthood clinic in Colorado on November 27th. The shocking murder has become a lightning rod for political debate across the country. In the wake of the killing, journalists nationwide worked to uncover Robert Dear's past and possible motivations for the attack.

What has been uncovered about Dear so far is a portrait of a troubled man. Dear was arrested several times, usually for what police describe as conflicts with neighbors. There was an allegation in 1997 of a domestic assault involving Dear's now ex-wife. In 2002 a neighbor says that Dear lurked in her bushes and peeped at her through her windows at night. Then in 2003, another neighbor told police that Dear shot his dog with a pellet gun. Dear denied shooting the dog, but told police:

"[The neighbor] was lucky that it was only a pellet that hit the dog and not a bigger round."

Dear was charged for animal cruelty for that incident, but the charges were eventually dropped.

The Puppycide Database Project researches the killing of animals by law enforcement. As we began compiling more and more information about "puppycide", more and more questions became apparent. We have recorded thousands of incidents in which police use lethal force against animals, but we did not know much about civilian animal abuse trends. Understanding the rates in which the overall population kills or seriously injures pets can help us to better understand the relationship between police and pets. Are police officers more or less likely to, for example, kill a dog than any average adult in their age group? What can the injury rates for dog attacks among civilians with jobs that force them to regularly come into contact with canines - like postal workers - teach us about how police should interact with dogs? Perhaps most critically: is animal cruelty or killing a reliable predictor for future acts of violence toward human beings?

The Puppycide Database Project did not invent the idea of a relationship between cruelty toward animals and violence toward humans. 230 years ago, influential moral philosopher Immanuel Kant made exactly that argument in formulating the idea of an ethical responsibility toward animals in his Lectures on Ethics:

"If a man shoots his dog because the animal is no longer capable of service, he does not fail in his duty to the dog, for the dog cannot judge, but his act is inhuman and damages in himself that humanity which it is his duty to show towards mankind. If he is not to stifle his human feelings, he must practice kindness towards animals, for he who is cruel to animals becomes hard also in his dealings with men."

But even Kant couldn't claim responsibility for the notion. Prior to the publication of Lectures on Ethics, there was talk of preventing slaughterhouse butchers from voting and holding public office throughout the UK. As one man put it when asked, in 1848, about butchers at the nearby Smithfield Market:

“[violence against the animals] educate[d] the men in the practice of violence and cruelty, so that they seem to have no restraint on the use of it” - Fitzgerald, A Social History of the Slaughterhouse

The justification for such a peculiar prohibition was the idea that a life of killing animals deadened the slaughterhouse employees' sense of empathy for human beings. To be clear, Puppycide Database Project has nothing against the people who make sausage & steaks. Our point is only that many people have felt that how people treat animals plays a role in how they treat human beings.

More recently, we find the notion that cruelty toward animals predicts cruelty toward humans can be found in medicine. The "Macdonald Triad" was first presented by psychiatrist J.M. Macdonald in his 1963 submission to the American Journal of Psychiatry "The Threat to Kill". Macdonald asserted that three factors predicted future violence, particularly serial murder and rape. These three factors were: animal cruelty, arson and bed wetting. The triad was quickly embraced by psychologists and law enforcement and has remained influential, although not uncontroversial, to the understanding of sociopathic criminals to this day.

One of the few studies of police misconduct currently available found that, within the Chicago Police Department, a small percentage of police officers account for over half of the complaints of misconduct filed by police departments (Futterman, Use of Statistical Evidence to Address Police Supervisory and Disciplinary Practices [PDF]).

It is possible that this relatively small group of officers are displaying the sort of serial violent behavior described by Macdonald. A small percentage of the total population display sociopathic behavior, and it is unclear why police departments would not include any such individuals. While such an explanation for violence among the police is not flattering, it spares the vast majority of officers from direct responsibility for excessive violence and presents a relatively straightforward method for addressing the problem: statistically identify officers engaging in excessive violence, and fire them. Futterman found that the Chicago Police Department had never attempted to identify "repeat offenders" among police officers, or officers who were routinely targeted for excessive force complaints. Ignorance is not bliss for the Chicago Police Department, who over a period of 10 years paid out over half a billion dollars to resolve litigation

Just how many animals are killed as part of animal cruelty incidents in the US? Are police more likely to kill pets than the population at large? Does the trend witnessed by Futterman among Chicago PD officers involved in excessive force complaints extend to other departments? Are police who kill or try to kill pets more likely to engage in excessive force toward human beings? If we are to answer these questions, it is imperative that we continue to gather data related to individual puppycides, use of force records for entire police departments and determine the rates of animal cruelty incidents among the US population as a whole.