Born at Auckland on 2 June 1915, James Carl Newhook was the eldest of three sons of James Lawrence Imrie Newhook, an English schoolmaster, and his wife, Marie Margaretha Franziska Coester, a teacher from Germany. He completed his secondary school education at Auckland Grammar School in 1931. He worked for a short period on dairy farms, before gaining a diploma in agriculture at Massey Agricultural College in 1935. These were depressed times for farming and his interest turned to veterinary science. An aunt assisted him to England for five years of study at the Royal College of Veterinary Surgeons, London. In 1941 he qualified MRCVS.
During the Second World War medically trained people were in short supply and Jim Newhook was assigned to Guy’s Hospital, London, as a clinical assistant. Enlisting for army service, he received his commission in 1942 and spent four years in the Middle East with the Royal Army Veterinary Corps looking after camels, mules and horses that were used for transporting equipment. Ready access to good mounts stimulated his interest in horsemanship, and towards the end of the war he gained selection and rode competitively in two army equestrian teams based in Italy, captaining at least one of them. When discharged in 1946 he had reached the rank of major.
On his return to New Zealand his long career at Massey Agricultural College began with his appointment to a lectureship in the department of veterinary pathology and animal physiology. On 4 December 1948 at Palmerston North he married Nola Mary Ciochetto; they were to have four children. During the 1950s he developed a part-time veterinary practice in the Palmerston North area, concentrating on treating small animals and horses.
The beginning of full veterinary training with the establishment of the Faculty of Veterinary Science on the Massey campus in 1962 brought new and more demanding opportunities, and he was appointed to a senior lectureship in the department of veterinary biology (later renamed physiology and anatomy) in 1963. He gave up his own practice and his academic career flourished. He set up anatomy courses for veterinary students and in January 1968 was promoted to reader.
His particular research interests involved the study of swallowing in lambs and of stomach movements in sheep, and he was admired for the skill with which he used radiographic techniques to advantage. Together with his head of department, D. A. Titchen, he published numerous articles on the subject. He also joined with his colleague David Blackmore in examining electroencephalograph (EEG) recordings to evaluate the effectiveness of humane slaughter techniques on sheep and cattle. Their published papers markedly improved understanding of the humane slaughter techniques used on these species. They assisted in introducing acceptable halal slaughter techniques to New Zealand, which opened up meat trade with Muslim countries.
Jim Newhook retired from Massey University in January 1981 and went to Tufts University in Boston as a visiting professor. A stroke later that year caused him to suffer indifferent health for the remainder of his life. After a period as a part-time senior teaching fellow in anatomy at Massey, he began to spend time with his son in Dunedin, finally moving there with his wife in 1988. He had always enjoyed writing, and contributed a regular series of articles on animal-related topics to the Otago Daily Times .
An ardent supporter of his profession, Jim Newhook played a large part in establishing the New Zealand Veterinary Journal , becoming its first editor (1952–69). In 1971 he was elected a foundation member of the Australian College of Veterinary Scientists. His community interests included active participation in the SPCA and the pony club movement. For many years he was veterinary officer to the Ashhurst–Pohangina racing club. He also enjoyed golf in earlier years, gardening, home renovating and bridge.
Always a gentleman, Jim Newhook was cheerful and friendly with a sharp wit. He was driven by high professional standards and he would not countenance anything that compromised these. Predeceased by his wife a few weeks earlier, he died in Dunedin on 17 May 1997, survived by three daughters and a son.