Johne’s disease (JD) is a progressive disease that causes economic losses due to decreased milk production, reproductive difficulties, and early culling. The true prevalence of disease is unknown and estimates across Canada vary based on province and method of testing. Much of JD control is based on the culling of positive animals and the adoption of management practices that minimize exposure of the pathogen (Mycobacterium avium ssp. paratuberculosis) to young stock. Between the years of 2010 and 2013, the province of Ontario instituted a voluntary Johne’s control program consisting of whole herd testing and risk assessment. The long-term effects of these agricultural extension programs in the control of diseases such as JD is unknown; our research hopes to describe these benefits and challenges. Using a modified milk ELISA technique (IDEXX) with an optical density cut-off of 0.089, province wide bulk tank (BT) milk testing has been used to assess the prevalence of Johne’s high-risk herds at the end of the control program and again 4 years after its completion. The prevalence of JD seems to have increased based on these BT samples. In 2013, 46.8% of bulk tanks tested positive (1828/3908), while in 2017, this increased to 71.4% (2557/3581). There were 3207 farms with matched test results (BT milk tests from 2013 and 2017). Of these farms with matched results, 1828 farms had participated in the voluntary Johne’s control program. When the results of the BT testing are dichotomized based on participation in the control program, 34% of participant herds remained positive compared with 40% of non-participants. 19.4% of participant herds remain negative compared with 18.6% of non-participant herds, and 36.2% of participant herds went from negative to positive status compared with 31.8% of non-participants. Both groups had a similar proportion of positive to negative status (10%, 9.9%). Preliminary results suggest additional factors are at play in the increase in JD prevalence in Ontario. In-depth investigations on specific management changes and producer barriers should assist us in developing effective agricultural extension programs for diseases such as Johne’s.