Ultimately, he changed his plans and traveled to Hong Kong under the London Missionary Society to replace Dr. Mitchell, due to Mitchell's illness, for a year and a half. Struthers arrived in Hong Kong February 20, 1913, and began working at the Alice Memorial Hospital. He lived with H.R. Wells. Along with a Dr Gibson, performed many unique operations, including a man with the congenital deformity of harelip and a boy with a tapering stone. He was responsible for the post-operative care and the eye ward. In September 1913, while still working at the Alice Memorial Hospital, Struthers also became the Warden of Morrison Hall, which was a hostel at the University of Hong Kong sponsored by the London Missionary Society. He oversaw students' activities and was responsible for the accounts. After his 18 month appointment in Hong Kong had ended, Struthers decided to leave for home and join the Canadian Presbyterian Board in September 1914 due to his lack of knowledge of Cantonese. However, in Welhei, he was convinced to stay and learn the language, and by 1915, he was working at the Henan province as part of a Canadian mission. In 1916, Struthers received a message from the British Minister in Peking to the Presbyterian Mission asking for missionaries who knew the Chinese language to serve in France. Struthers volunteered and was a captain in the Royal Army Medical Corps. He arrived in Noyelles-sur-mer, France, in July and started by running a gonorrhea and syphilis ward, helping at a hut with patients in serious condition, and monitoring the sanitation of a hospital. He also ran a hospital for the Chinese Labor Corps, and he worked in the Noyelles-sur-Mer hospital’s convalescent camp in the Crecy Forest as part of the Canada Army Medical Corps. In the summer of 1918, he worked 24 hours days at a shelter in Seignville. After the war, he completed five weeks of postgraduate study in New York. In February 1919, Struthers returned to China and became a physician at the Cheeloo University in Jinan, which was known as the Shantung Christian Union Medical College. It was considered the highest school of learning by 15 mission boards. In addition to practicing medicine, he taught pharmacology, therapeutics, tropical medicine, and internal medicine. In the summer of 1924, he went on furlough and did deputation work in Canada. He also spent six weeks doing clinical experience with Dr. Peabody at the Boston City Hospital.