Robert Black, 51, was sentenced to 23 weeks after he was filmed beating his pet during a "deliberate and gratuitous attempt to cause suffering".
He was also banned from owning animals for ten years after the appalling attack on the mixed-breed in Newbury, Berks., in December last year.
After showing a video of the offence, Adam Butler, prosecuting, said the defendant had launched a “gratuitous and deliberate attempt to cause suffering”.
But Steve Molloy, defending, said: "What you saw was his rather clumsy attempt to separate them.
"There’s no suggestion the dogs were undernourished or routinely ill-treated. This was, in my submission, a one-off incident. It’s not in the league of dog fighting or dog baiting."
He suggested the district judge who sentenced Black had erred in law by categorising the offence as ‘higher culpability’.
Mr Molloy conceded that his client had been subject to a suspended prison sentence at the time, but said this was for a totally unrelated offence.
He concluded: "Mr Black has now served a custodial sentence of some weeks and, in my respectful submission, the proper sentence would be one of time served."
That would have allowed Black to walk free and spend Christmas with his partner, who accompanied him to court.
But Judge Richard Wheeler pointed to Black’s 288 previous convictions for offences including battery, burglary, theft and being drunk and disorderly.
He said Black’s actions had breached the terms of a suspended prison sentence order.
Judge Wheeler added: "I’m perfectly satisfied it was correct in law to activate the five-week suspended sentence and to add a consecutive sentence for the current offence."
He told Black: "You committed this offence less than a month after the suspended sentence and you have a lengthy and extremely depressing record.
"But I’m persuaded to allow the appeal to this extent: while the five blows can be characterised as a deliberate and gratuitous attempt to cause harm to the dog, it was lesser harm, not greater harm.
"There was no prolonged suffering."
The judge ruled that 12 weeks imprisonment, rather than 18, should have been added consecutively to the five-week suspended sentence, reducing the total to 17 weeks rather than 22.
He said the ten-year ban on keeping animals would remain in force.
Black, from Newbury, Berks., was initially jailed under the Animal Welfare Act 2006 at Reading Magistrates' Court on November 12.
He was convicted of causing unnecessary suffering to an animal.
Speaking at the time, investigating officer PC David Burleigh said: "Black demonstrated significant cruelty to his dog by punching it several times in the face, with no concern for its welfare."