Professor Barrett’s main areas of interest are production ruminant health and disease, bovine mastitis / milk quality, bovine respiratory disease and veterinary education. In addition to these numerous other clinical/research areas are of interest to him including; bovine reproduction, bovine lameness, biosecurity and herd health planning, bovine tuberculosis, displaced abomasum, impact of animal production methods on food safety, responsible use of medicines and a number of other specific clinical entities. He currently supervises the training of six postgraduate European clinical residents and co-supervises a PhD student undertaking a project entitled, Carriage of Bacterial Pathogens in the Bovine Upper Respiratory Tract: Effects of Respiratory Virus Vaccination.
He is a former editor of the journal Cattle Practice, and a current member of the editorial boards of The Veterinary Journal and Livestock.