The cold-blooded execution that was carried out on December 12, also included Thaek's five close aides.
The previous executions of political prisoners were carried out by firing squads with machine guns.
According to the Straits Times, 120 hounds were starved for three days, and then they were allowed to prey on Jang and five others until they were completely eaten up.
The report said the entire process lasted for an hour, with Kim Jong Un supervising it along with 300 senior officials, the report added.
67-year-old Jang was also known to be a "drug-addicted womaniser".
Kim Jong Un 'hailed' his Uncle's execution by saying the removal of "scum elements" had helped cement unity among his people.
67-year-old Jang was executed on number of charges including plotting a coup and corruption.
Jang was also known to be a "drug-addicted womaniser" who pocketed millions of dollars of state money to support his lifestyle.
Jang had been removed from all his posts because of allegations of corruption, drug use, gambling, womanising and generally leading a "dissolute and depraved life".
Jang was considered the second most powerful official in the North. Kim Jong Un rose to power after the death of his father and long-time ruler, Kim Jong-Il, in December 2011.
(With agency inputs)