John Cammack, of Boston, Lincolnshire, qualified as a member of the Royal College of Veterinary Surgeons (MRCVS)at the Royal (Dick) Veterinary College in Edinburgh in April 1872. He practiced in Staffordshire, England, until at least March 1878, but came to Cape Town in or before 1880. As far as is known he was the first qualified veterinary surgeon in private practice at the Cape of Good Hope. In November 1882 he was practising in Kimberley.
In August 1880 Cammack published an article, "Hydrate of chloral in veterinary practice", in the (British) Veterinary Journal. The manuscript had been submitted from Cape Town. He is credited with being the first person, in 1884, to recommend the preventive treatment of lamsiekte (botulism) by feeding livestock bones or bone ash. The recommendation was based on tests he carried out with bone ash near Kimberley, which showed it to be effective in halting the disease. Later he contributed an item with the rather obscure title "A periscope from the pastoral plane" to the South African Agriculturalists' Almanac for 1889.
In September 1890 Cammack was appointed by S. Wiltshire*, principle veterinary surgeon of Natal, as deputy inspector of cattle in Durban. By January 1892 he was known for his treatment of horse sickness, apparently in association with a veterinary hospital in Johannesburg. In 1901, during the Anglo-Boer War (1899-1902) he applied for the post of veterinary surgeon to the Utrecht-Vryheid Mounted Police. He set up a practice in Johannesburg, worked at the veterinary hospital there, and died in the city in 1911, at the age of 67 years.