He also became an expert breeder of sheep, horses, and cattle, and served in a leadership role in many agricultural and animal husbandry organizations.

Dryden's political career began in the local arena; in 1863, he was elected to the Whitby Township council, becoming Reeve in 1869 and 1870.

These measures were designed to improve the quality of dairy products produced in Ontario in an environment characterised by American tariffs and export challenges.

In 1895, Dryden set up an experimental farm near Wabigoon Lake in northwestern Ontario to test the agricultural potential of the area.

In 1897, he appointed his brother George W. Dryden as the Registrar of Ontario County, causing dissension among fellow Liberals also interested in the job.

He continued his affiliation with McMaster, served as president of a number of insurance and savings companies and was appointed to an Imperial Royal Commission on agricultural conditions in Ireland.