Serial killers often start their criminal careers as animal abusers, research has claimed.
Psychologists and criminologists have found those who inflict violence on humans often begin by harming their pets.
The research, conducted on behalf of campaign group People for the Ethical Treatment of Animals (PETA), is being sent to judges, magistrates and senior police officers today.
It urges prosecutors to hand out strict sentences to those who commit cruelty to animals and encourages the police to take animal abuse complaints seriously.
Kate Fowler- Reeves, from PETA, said: "Animal abuse is not just the result of a minor personality flaw. It is a symptom of a deep mental disturbance.
"Research in psychology and criminology shows that people who commit acts of cruelty to animals don't just stop there. Many move on to harm their fellow humans.
"Researchers have found that a batterer's first target is often an animal living in the home and that the second tends to be a spouse or child."
Moors murderer Ian Brady, "Railway Killers" David Mulcahy and John Duffy, who raped and murdered women in the 1980s, and Gavin McGuire, a convicted rapist and murderer, all "practised" their crimes on animals and "graduated" to killing humans.
In the United States, the FBI uses reports of animal abuse to consider how threatening potential criminals might be.