Dr McCann co-founded with her husband Peter McCann Clouds House, an addiction centre in Wiltshire, where she established the detoxification and treatment programme. She was responsible for directing all treatment services, including medical, nursing and therapeutic; she pioneered the use of Clonidine for detoxification from opiates in the UK.

In 1988 Dr McCann moved with her husband to Scotland, where they founded Castle Craig Hospital. There she established the treatment programme and continues to focus on the development of therapies for the treatment of addiction and the direction and governance of the hospital. Dr McCann also acted for a period as Medical Director for Castle Craig’s clinics in the Netherlands – which provide assessment, continuing care and other outpatient services.

Until 2021 Dr McCann was the CEO of Castle Craig. Dr McCann has presented at a number of medical conferences in the UK. She is committed to promoting and sharing best practices in the addiction field. Dr McCann completed a degree in medicine at University College Dublin and worked in hospitals in the Republic of Ireland and Northern Ireland.