Rolf Ernst Hartig studied at the Königliche Sachsische Technische Hochschule in Dresden, where he qualified as a veterinary surgeon in 1904. Three years later he obtained his Doctor Medicinae Veterinariae (Dr Med Vet) at the University of Zürich with a thesis on the comparative anatomy of domestic mammals and apes. Meanwhile he had entered the German Army as a veterinary officer in 1906 and took part in the Herero War in German South West Africa (now Namibia).
After the war, from 1908, Hartig was in charge of a large German farming operation in the territory until 1919. He then started his own laboratory in Stellenbosch to study lamsiekte (botulism) in cattle and that same year patented an antidote for the disease. He read a paper on the disease at the annual congress of the South African Association for the Advancement of Science in 1921, but clashed with Dr Arnold Theiler* about the lack of scientific evidence in support of his patent. As a result he gave up the venture and returned to Germany in 1922, where he studied the diseases of fur animals.
In 1928 Hartig returned to Namibia to start a cheese factory in Gobabis, but the venture failed. The next year he opened a private practice in Cape Town, but soon moved to Paarl. After the outbreak of World War II he was interred from 1940 to October 1943, when he was released but restricted to Pretoria and forbidden to practice. During his internment he wrote Afrikaanse dieresiektes and later published some articles in the Farmer's Weekly. Towards the end of the war, in 1944 he started practising in Pretoria until 1953, and thereafter briefly acted as locum tenens at Koppies, in the Free State. He died of coronary thrombosis.