Thomas Robinson, 18, of Water Street, Stamford, appeared before magistrates on Wednesday for sentencing, after being found guilty of causing unnecessary suffering to the dog. He had denied the charge.
But the Stamford man who is said to have actually instigated the attack on the animal, called Minty, has not yet appeared in court.
John Bagster, who is 20 and used to live in York Road, failed to turn up for a hearing on July 31 and a warrant was issued for his arrest. He has still not been found and the RSPCA says anyone who knows where he is should call the 24-hour hotline on 0300 1234 999.
The dog has since been rehomed with a loving family and has recovered fully.
Kevin McCole, prosecuting for the RSPCA, told Grantham court on Wednesday that the incident happened on January 23. Robinson was staying at York Road with John Bagster when a neighbour reported hearing distressing sounds coming from the house and at 10.30pm, heard loud banging and voices.
He said: "The neighbour heard the dog howling, crying, whining and yelping. He could clearly hear a man's voice saying 'I am going to kill you', so he felt inclined to call the police and the RSPCA."
Mr McCole said the neigh-bour looked through a window and saw Bagster holding a saucepan, which he kept banging down. A dog could clearly be heard yelping. Robin-son then went into the room. Mr McCole said Bagster's girlfriend stayed upstairs because "she said she was terrified and thought they were going to kill Minty".
When RSPCA inspectors arrived they found 16-week-old Minty cowering under a cup-board. It had severe swelling and bruising to its back and a broken leg and an examination showed it had suffered multiple fractures over a period of time.
Mr McCole said: "The RSPCA would take the view it was a serious offence."
Robinson's lawyer Christopher Pye-Smith said his client was a secondary participant" in the incident.
"Mr Robinson aided and abetted the assault," he said. "He wasn't the owner of the dog. It couldn't be said that he was responsible for the whole of the injuries."
Magistrates sentenced Rob-inson, who is a college student, to a community sentence over 12 months to do unpaid work for 80 hours.
He will also be supervised and will have to complete an enhanced thinking programme. He was banned from keeping animals for 15 years and cannot apply to have the disqualification lifted for 10 years.
He was told to pay costs of £250.
After the case, RSPCA inspector Claire Mitchell said: "I think it's important from a moral point of view if you know something is happening to an animal you should seek to do something."
Anyone can make an anonymous call if they don't want to leave their details."