Walter Doe, 24, of East Sussex used a sharp tool on his eight-week-old Jack Russell to remove its tail, leaving it to suffer.
As well as being sentenced to 12 weeks in prison for causing unnecessary suffering, he has also been banned from owning an animal for 10 years.
Following the attack, Walter then left the poor puppy in agony and did not seek medical attention for it.
While the weapon used to cut the puppy’s tail is unknown, the RSPCA are certain whatever it was would have caused immense pain to the defenceless animal.
RSPCA Inspector Andrew Kirby told a UK newspaper: “The prison sentence reflects how seriously the court took the suffering caused to the puppy.
“We have no proof about what was used to dock Jack’s tail but, whether it was a knife or a pair of scissors, he would have been in agony.
“Cutting through the bone of the tail must have been excruciatingly painful and no attempt at all was made to relieve this pain.”
The RSPCA removed the puppy from Walter last year after they received reports leading them to be concerned for its welfare.
Andrew added: “As well as the pain it causes, it’s just completely unnecessary and deprives the animal of their best means of expression and balance.”
The puppy is now safe and living in foster care.