J Rangarajan was born into a dog loving family and evinced great interest in training dogs right from his young age. He was only 14 when he trained his first dog. He has won many awards in Obedience Trials at various dog shows. In the year 1988, he started Woodstock Dog Training School at Chennai and the services from his institution are well sought after. In the same year, he was granted License by the Kennel Club of India to judge Obedience Trials and since then he has judged shows extensively. In the year 2001, Rangarajan migrated to the USA with his family and he opened a branch of Woodstock in the USA. He is an approved Canine Good Citizen Evaluator by the American Kennel Club. In the year 2009, Rangarajan was appointed by the Tamil Nadu Government to train dogs for Search and Rescue work for the Tamil Nadu Fire and Rescue Services. This is the first ever Rescue Service Dog Squad in the country.

Rangarajan is one of the founding members of the Madras Canine Club and has been a member of the Kennel Club of India for close to three decades.