Anthony 'Harpo' O'Driscoll was held after an incident involving the helpless animal last Saturday.
O'Driscoll (33) was arrested after reports that the horse had been run over by a stolen car, and left with fatal injuries.
The horse had its back and legs broken and had to be put down.
It was crushed by the car in a field beside Labre Park, Bally-fermot, at around 11pm on Saturday. O'Driscoll was detained after gardai received a report that a stolen car was driving in the area.
The driver was suspected of running over the horse, breaking its back and legs.
Officers managed to stop the car and arrested O'Driscoll at the scene.
As he was being taken to the garda station, a vet was called for the animal, which had to be put down. O'Driscoll was questioned at Ballyfermot Garda Station and later released without charge on Sunday, pending further garda enquiries.
A garda spokesperson told the Herald that investigations were ongoing.
'Harpo' O'Driscoll (33) is a notorious local criminal and brother of Dee Dee O'Driscoll. Dee Dee is regarded as a leading gangster in Ballyfermot.
A chronic drug addict from Croftwood Park, Ballyfermot, 'Harpo' O'Driscoll was recently released from prison.
He has a convictions going back to the age of 12 for offences including assault causing harm, possession of heroin, attempted burglary, damage to property, unlawful carriage, criminal damage, larceny, and road traffic offences.
He last hit the headlines when he was forced to pay €1,000 in compensation last year, after wrecking a holding cell in Mountjoy Prison with another convict.
He has served time for drugs offences in the past, after he was watched by gardai as he dug up IR£200,000 worth of heroin from under a railway sleeper back in February 1996. He was then aged 18.
During his four-day trial, alibi evidence was given for him by his brother Dee Dee, who was then serving a jail sentence for bribing the former garda Scott Medal hero, John O'Neill.
After completing his heroin sentence 'Harpo' O'Driscoll was back before the courts in 2008, when he pleaded guilty to a litany of offences including drug dealing, attempted burglary, unlawful carriage, property damage and seriously assaulting a man.