A Sydney psychologist has been banned from practicing for a decade after he encouraged a female patient to have sex with a dog.

Gareth Michael Dawes, who had practices at Parramatta and Penrith, has been found by the NSW Health Cares Complaint Commission to have "manipulated" his client, who cannot be named for legal reasons, to "fulfil his own sexual fantasies".

The young woman, a university student, who suffered from psychological issues arising from sexual and physical abuse and neglect, was a client of Dawes between January 2011 and April 2012.

During this time Dawes and the patient sent each other about 3000 emails – many of which had images, videos and website links to pornography within them.

The pair began a sexual relationship in September 2011 which took place in his offices and in secluded public places. In December 2011, the HCCC said Dawes began encouraging the woman to engage in bestiality by having sex with dogs by sending her emails and images about the topic.