People found guilty of animal cruelty go on to commit a huge number of other offences - including murder - but nine out of 10 cases do not result in a prison sentence, a report has warned.
In the 10 years leading up to the end of 2015, 13,835 offences were committed by those with a previous conviction, or caution for animal cruelty, including murder and rape.
But the Centre for Crime Prevention, which compiled the report, said that despite the seriousness of animal cruelty offences and the strong evidence of links to other crimes, serious penalties are extremely rare, with more than 92% of those found guilty avoiding prison.
Among those given a fine or a suspended sentence rather than going to prison were criminals who starved a dog to death, strangled a cat and threw it in the bin, filmed themselves throwing a bulldog down the stairs so many times that she had to be put down, and set a puppy on fire.
Those convicted of animal cruelty offences have gone on to commit thousands of crimes, including robbery, theft, the rape and neglect of children, and murder.
Animal cruelty is also overwhelmingly committed by people already found guilty of previous offences, with half (48%) of those convicted of animal cruelty offences already having at least four previous convictions or cautions for other crimes.
The Centre for Crime Prevention, which campaigns for better prevention of crime, is calling for tougher sentences for animal cruelty to "protect people and animals alike".
Its analysis found that of the 13,835 offences committed by those with a previous conviction or caution for animal cruelty over 10 years, 1,437 were violent offences - 16 of them murders.
They were also behind 202 sexual offences, including 19 rapes of a female under 16, eight rapes of a child under 13, and 26 cases of sexual assault on a female under 13.
There were 97 cases of cruelty or neglect to children by those who had previously been cruel to animals, while they committed 175 robberies and 5,557 thefts.
Three out of four (73%) criminals convicted of animal cruelty offences already had at least one previous conviction or caution while one in four (28%) had at least 10 previous convictions or cautions.
But the report said that of the 13,862 criminals convicted or cautioned for animal cruelty, just 1,063 (7.7%) received a prison sentence.
A third (34%) resulted in community service, while a quarter (24%) were punished with only a fine.
The size of these fines has also dropped over the past decade, falling from an average of £479 in 2005 to just £296 in 2016.
The report also highlights regional variation among the proportion of animal cruelty cases resulting in a prison sentence, from 28.1% in Cumbria to just 1.4% in Surrey.
Durham and Warwickshire have the two next lowest amounts (3% and 3.3% respectively), while the next greatest are Northamptonshire and Derbyshire (18.9% and 18.8%).
The report said the current maximum sentence for animal cruelty of six months in prison is the lowest in Europe and recommends that it should be brought in line with Northern Ireland and increased to five years.
Peter Cuthbertson, director of the Centre for Crime Prevention, said: "Animal lovers will be horrified to learn that animal cruelty is one of the many offences treated extremely leniently by our courts.
"The Government is currently exploring tougher sentences for animal cruelty. This is absolutely necessary.
"We need more serious, prolific criminals in prison. This would protect people and animals alike, because it's so often the same criminals who are a threat to both people and animals."
Ranil Jayawardena, MP for North East Hampshire, who contributed to the report, said: "Deliberately causing pain, suffering or death to pets is wholly abhorrent. The problem is that bad people are still getting away with it.
"I am shocked at the number of animal abuse offenders who are either repeat offenders, or who have been convicted of other, often violent, offences. It is staggering.
"These are not only bad people, they are very dangerous. We must do more."
The RSPCA said it would also like to see the maximum sentence increased to five years.
Its interim chief executive, Michael Ward, said: "While the RSPCA is seeing unbelievably shocking and distressing cases go before the courts, only a tiny proportion of animal abusers actually receive an immediate custodial sentence.
"It's ironic that in some puppy trade cases we've taken, the defendants get longer sentences for committing fraud than for the cruelty and suffering they have inflicted on the defenceless dogs.
"RSPCA officers have had to investigate horrendous cases in which dogs have been found buried alive with a nail hammered into their skull, puppies have been kept in damp, dark rooms laying in their own filth and sold to unsuspecting members of the public, horses have been dumped to die on the side of the road and hamsters have been force-fed drugs."
The charity said a poll had found that seven out of 10 people would like to see sentencing for animal welfare offences toughened up and longer jail terms imposed on offenders who commit the worst cruelty.