From 1908, he served as demonstrator of bacteriology and comparative pathology at the Royal Institute of Public Health in London, before he was employed by the Imperial Health Office in Berlin in 1910.
He undertook several research expeditions in China, Japan and Russia.
In 1919, he returned to Germany, and worked for a number of scientific institutions, before he was appointed associate professor at the University of Marburg in 1926.
Dold published works on tropical medicine, tuberculosis, syphilis and on antibacterial inhibitory substances and conversion.
He was one of the editors of the influential journal Medical Microbiology and Immunology.