Peter Conacher, son of a veterinarian, qualified as a member of the Royal College of Veterinary Surgeons (MRCVS) of Edinburgh at the Royal (Dick) Veterinary College, Edinburgh, in May 1889. During the 1890s he was commissioned by the British government to purchase horses in the United States. He came to South Africa during the Anglo-Boer War (1899-1902) as a civil veterinary surgeon in the Imperial Remount Department, serving in the Cape Colony and Transvaal, and was awarded both the King's and Queen's medals (4 bars). Subsequently he was sent to Australia to investigate an outbreak of contagious disease among horses arriving in South Africa from there. Meanwhile he had been appointed in July 1902 as government veterinary officer for the Witwatersrand in the Department of Agriculture of the Transvaal Colony and from March 1905 was stationed in Johannesburg.
Conacher's main contribution to the development of veterinary science came in 1908, when he was seconded to the administration of Mozambique to set up a veterinary department there. He and O.W. Barrett represented that territory at the Pan African Veterinary Conference held in Pretoria in January 1909 to coincide with the official opening of the Veterinary Research Laboratory at Onderstepoort. Following the formation of the Union of South Africa in 1910 Conacher was re-appointed as district veterinary surgeon by the new administration, but by 1914 was apparently still serving in Mozambique as he received a personal allowance. He was still registered as a veterinarian in 1929, at which time he resided in Johannesburg. He was married to Amy Carruthers, but they were divorced in 1947 and had no children.