Piet Vellema qualified as DVM from Utrecht University and its Faculty of Veterinary Medicine in 1980. After one year in farm animal veterinary practice, he joined Royal GD, first in Drachten and later in Deventer. In 1996, he completed his PhD with his thesis ‘Cobalt/vitamin B12 deficiency in lambs on pasture. A randomized trial’. Since April 1997, he is registered as Specialist in Small Ruminant Health Care, according to the Registration Committee of the Board for Veterinary Specialisation of the Royal Netherlands Veterinary Association, and since April 2008, he is a Diplomate of the European College of Small Ruminant Health Management.

Piet Vellema was head of the Department of Small Ruminant Health at Royal GD, Deventer, the Netherlands, until his pre-retirement in May 2020, when he decided to slow down and start working four days a week. Although he officially retired in July 2022, he is still active from his own consultancy organization Rispinge.

Piet Vellema has interests in crisis management of outbreaks of infectious diseases, and in planned small ruminant health and production. From 1998 onwards, he was chairman of the Dutch Liver Fluke Forecast Committee, and between 2000 and 2006, he was project leader of the Dutch National Scrapie Plan, aiming at breeding for scrapie resistance. From 2004 onwards, he has participated in projects in Hungary, Romania, Poland, Italy, Germany, and Russia.

Piet Vellema has been member of the central crisis team during the foot-and-mouth disease epidemic (2001), and the bluetongue outbreak (2006) in the Netherlands. He has been member of the Q fever (2007-2010) Outbreak Management Team and member of the expert team Q fever, Schmallenberg virus, and Chlamydia abortus. From September 2013 to April 2023, he was a member of the Animal Diseases Expert Team of the Ministry of Agriculture, Nature and Food Quality. Between 2005 and 2011, he was a member of the board of the European College of Small Ruminant Health Management. Since 2017, he was Executive Committee Member, and since March 2023, he is vice president of the International Sheep Veterinary Association. He is an active board member and committee member in other organizations, both within and outside the veterinary field.

Piet Vellema has published over hundred papers in scientific journals, and has given presentations on small ruminant health all over the world. He is first author of ‘Handboek schapeziekten’ (Handbook of sheep diseases) and author of ‘Gezonde schapen’ (Healthy sheep) (both books only available in Dutch), and author of two chapters in ‘Differential diagnosis in sheep’.