After his ordination, Dowd was assigned as an assistant pastor at the Montréal parishes of Holy Name of Jesus between 2001 and 2002 and Saint Thomas à Becket between 2002 and 2005. Between 2005 and 2006, He was the parish administrator of St. Veronica and assistant pastor of St. Luke. In 2005 until 2006, Dowd also served as the hospital chaplain for Lakeshore General Hospital in Pointe-Claire. From September 2006 until his episcopal ordination, Dowd worked as part of the diocesan curia as Associate Director for the Office of Pastoral Personnel, and as Director of the Diocesan Formation Services. Having been in the technological market before his ordination, Dowd started a blog in 2003. Dowd was the first Canadian priest to have a blog. Also, Dowd was the person responsible for the Canadian Conference of Catholic Bishops online presence; the first Episcopal Conference to have a website. Dowd continues to use Facebook, Twitter, Reddit and his own personal website to reach out to members of the Church and the world. In 2004 Dowd contributed to the development of the fifth edition of the Ars Magicarole playing game. He was credited in the core rule book for a design contribution as well as for being a play tester. He later received play test credit in other rule books, namely Calebais: the Broken Covenant, Realms of Power: The Divine, and Realms of Power: The Infernal Dowd began studies in canon law in 2010, prior to being named a bishop. He continued those studies part time while a bishop, eventually obtaining a Licentiate in Canon Law from the Institut de droit canonique in 2018.
On March 27, 2019, it was reported that Dowd had played a key role in the investigation of Brian Boucher, a priest who was sentenced to 8 years in prison for sexually abusing two young boys. Through his investigation Dowd discovered one of the two victims, who Dowd accompanied to the Montréal police. Dowd also turned over his 250-page report to assist in the police investigation. Justice Patricia Compagnone, who presided Boucher's trial, applauded the church's involvement. In a statement immediately after the sentencing on March 25, 2019, Dowd thanked the victims, the police, the crown prosecutor and the judge, and also condemned the actions of Brian Boucher. He also revealed that the investigation had led him to a time of depression and burnout, but pledged to strive to bring justice and healing should he encounter similar situations in the future. Dowd spoke about his own childhood experiences of abuse at a lay-run summer camp in subsequent interviews. The noted Vaticanologist John Allen offered some subsequent analysis of Dowd's work after being prompted to do so by an abuse victim. On April 3, 2019, one of the victims of Brian Boucher applied for authorization for a class action against the archdiocese of Montreal. On June 20, 2019, CBC Montreal published an investigative report: "Montreal sexual abuse victim says Catholic clergy interrogated him, looking for inconsistencies in his story." A.B. was asked by Dowd to attend a meeting in late 2016 concerning his experiences with Brian Boucher. According to the article, A.B. was grilled for several hours by 9 members of the clergy, some dressed in full church regalia, in the same place where he had been molested. The Archdiocese has not responded to the article, citing the legal proceedings already underway. Dowd was part of a small group of bishops that attended a screening of the film Preyin September 2019, where he and the other bishops had a chance to dialogue with survivors of clergy sexual abuse. On October 1, 2019, he participated in the radio show Ottawa Morning with Robyn Bresnahan as a follow up. On November 16, 2019, the published an opinion piece written by Dowd about the experiences of watching the film.