Zoosadism
Zoosadism is pleasure derived from cruelty to animals. It is part of the Macdonald triad, a set of three behaviors that are considered a precursor to psychopathic behavior.

Research
Some studies have suggested that individuals who are cruel to animals are more likely to be violent to humans. According to The New York Times:

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.

Examples
An adult man in Cuba, by the name of Rubén Marrero Pernas was found to be raping, torturing then killing dogs or puppies and recording the acts online for an audience who found this to be likewise sexually gratifying.Serial killer Jeffrey Dahmer was known for torturing and killing animals in his youth, such as poisoning tadpoles.

Legal status
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.

See also
Bloodsport
Cruelty to animals

References
External links
Four-legged Forensics: What Forensic Nurses Need to Know and Do About Animal Cruelty