In 2001, Julien graduated from the National Veterinary School of Nantes. Following an internship at the French veterinary school of Alfort, near Paris, he gained experience working in private practices, both in referral and general practice, and served as a clinical instructor in Emergency and Critical Care at the French veterinary school of Lyon. In 2005, he relocated to the USA, where he worked at UC Davis and Cornell University, and completed an ECC residency at UC Davis. In 2009, Julien was appointed as an assistant professor at Ohio State University and was promoted to Associate Professor in 2015. His role at Ohio State University was primarily clinical, though he also conducted significant research. In 2019, he moved to Colorado State University where he currently hold the rank of Tenured Professor. For the past several years, one of his interests have been teaching point-of-care Ultrasound, especially cardiac POCUS.