Gabriel Radzikowski, 29, hatched the plan when former neighbour Sara Lilly was unable to use her position at Lloyds to help him, Nollywoodgossip has learned.
He broke into her garden in Bath, Somerset, at night and snatched her Yorkshire Terrier Bilbo Baggins.
He then phoned Ms Lilly, 48, posing as a man called Martin who found the pet, demanding £500 for its return.
But the distraught owner – a regional director for Lloyds – recognised his voice and called the police.
Realising his plan would fail, Polish-born Radzikowski tried to drown the dog by smashing a hole in the ice on a frozen pond and dumping him in the water.
The 15-year-old dog was rescued by a passer-by. Ms Lilly told Bristol Crown Court: “I don’t have children so he is my child in a certain way. He is my pet and I love him. It was dreadful.”
Radzikowski denied blackmail and intimidation. He claimed it was a conspiracy to put him in jail.
He was convicted after a three-day trial. Judge Michael Longman told him: “Your motive was financial and to get your own back. It was calculated and cruel.”
Radzikowski, who served 181 days on remand, also admitted intimidating four people linked to the case, including a Polish family who took him in.
He may be liable to deportation on his release.