The FBI has found that a history of cruelty to animals is one of the traits that regularly appear in its computer records of serial rapists and murderers, and the standard diagnostic and treatment manual for psychiatric and emotional disorders lists cruelty to animals as a diagnostic criterion for conduct disorders.
Helen Gavin wrote however in Criminological and Forensic Psychology (2013):
This is not a universal trait, though. Dennis Nilsen had difficulty initiating social contact with people, but loved his faithful companion, Bleep, a mongrel bitch. After his arrest, he was very concerned for her welfare, as she was taken to the police station too.
Alan R. Felthous reported in his paper "Aggression Against Cats, Dogs, and People" (1980):
A survey of psychiatric patients who had repeatedly tortured dogs and cats found all of them had high levels of aggression toward people as well, including one patient who had murdered a boy.
This is a commonly reported finding, and for this reason, cruelty to animals is often considered a warning sign of potential violence towards humans.
In the United States, since 2010, it has been a federal offense to create or distribute "obscene" depictions of "living non-human mammals, birds, reptiles, or amphibians ... subjected to serious bodily injury". This statute replaced an overly broad 1999 statute which was found unconstitutional in United States v. Stevens.
Criticism of alleged Link to violence against humans
On the other hand, Piers Beirne, a professor of criminology at the University of Southern Maine, has criticized existing studies for ignoring socially accepted practices of violence against animals, such as animal slaughter and vivisection, that might be linked to violence against humans.
- J. M. MacDonald (1963). "The Threat to Kill". American Journal of Psychiatry. 120 (2): 125–130. doi:10.1176/ajp.120.2.125.
- Goleman, Daniel (7 August 1991). "Child's Love of Cruelty May Hint at the Future Killer". New York Times.
- Helen Gavin (2013). Criminological and Forensic Psychology. p. 120.
- Felthous, Alan R. (1980). "Aggression Against Cats, Dogs, and People". Child Psychiatry and Human Development. 10: 169–177. doi:10.1007/bf01433629.
- Robson, Ruthann (2010-12-14) Animal Porn - Criminalized by Federal Law Again Archived 2011-04-15 at the Wayback Machine, Constitutional Law Prof Blog
- "18 U.S. Code § 48 - Animal crush videos". LII / Legal Information Institute. Archived from the original on 21 November 2011. Retrieved 23 April 2018.
- "Archived copy". Archived from the original on 2017-11-07. Retrieved 2017-11-08.CS1 maint: archived copy as title (link)