Ovine pulmonary adenocarcinoma be predisposed to OPA. Most affected sheep show signs at 2 to 4 years of age. OPA is not a notifiable disease, and therefore it is difficult to assess its prevalence. OPA was first described in the UK in 1888, and described in detail in South Africa in 1891. The disease was initially known as "jaagsiekte" , a word derived from Afrikaans, meaning "chasing sickness," so called because animals are in respiratory distress as if they are out of breath from being chased. It has also been known as sheep pulmonary adenomatosis and ovine pulmonary carcinoma. OPA has been used
Animal studies Animal studies Animal studies is a recently recognized field in which animals are studied in a variety of cross-disciplinary ways. Scholars who engage in animal studies may be formally trained in a number of diverse fields, including geography, art history, anthropology, biology, film studies, geography, history, psychology, literary studies, museology, philosophy, communication, and sociology. They may engage with questions about literal animals, or about notions of "animality" or "brutality," employing various theoretical perspectives, including feminism, Marxist theory, and queer theory. Using these perspectives, those who engage in animal studies seek to understand both human-animal relations now and in the past,