James W. Crowhurst came from a family with many veterinarians, including his father James (FRCVS). James Jnr went to school in Canterbury and then qualified as a member of the Royal College of Veterinary Surgeons (MRCVS) in London in 1887. He obtained his FRCVS in 1892, but is not known to have submitted a thesis. He arrived in the Cape Colony in December 1893 with three other veterinarians (R.W. Dixon*, M.A. Hutchence and H.A. Pattison*), who had all been appointed by the Cape government at the request of the Colonial Veterinary Surgeon, Duncan Hutcheon*. In 1895 Crowhurst claimed to have reproduced Euphorbia poisoning exerimentally by feeding Euphorbia genistoides to an ox, but unfortunately the experiment was interrupted and the records remained incomplete. From then on he was stationed mainly at Stellenbosch, where he also filled the position of veterinary lecturer at Elsenburg Agricultural College. He was retrenched in 1899 and started a private practice in Cape Town.
In 1901 Crowhurst took up the position of veterinary surgeon to the Table Bay Harbour Board, a post he held until the outbreak of World War I (1914-1918). During these years he was also honorary veterinarian to the Kennel Association, Cape Town, and veterinary captain in Prince Alfred's Own Cape Field Artillery. In 1905 he became a foundation member of the Cape of Good Hope Veterinary Medical Society, serving as vice-president during its first year and thereafter as honorary secretary and treasurer or member of council until 1914. During World War I he was a captain in the South African Veterinary Corps and from October 1914 was in charge of the ship of the British Army Veterinary Service. After the war he returned to Elsenburg, where he lectured in veterinary science and was in charge of the health of the college's animals.
Crowhurst was a member of the South African Philosophical Society from 1895 to about 1900. He became a member of the South African Veterinary Medical Association at its formation in 1920, and was still registered as a veterinarian in 1929. In 1902 he married Lily Margaret May Wolfe, with whom he had at least two children. His hobbies included photography and bowling.