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 rights Linzey at Trinity College, Cambridge, in August 1977. This was followed by Mary Midgley's "Beast And Man: The Roots of Human Nature" (1978), then "Animal Rights–A Symposium" (1979), which included the papers delivered to the Cambridge conference. From 1982 onwards, a series of articles by Tom Regan led to his "The Case for Animal Rights" (1984), in which he argues that nonhuman animals are "subjects-of-a-life", and therefore possessors of moral rights, a work regarded as a key text in animal rights theory. Regan wrote in 2001 that philosophers had written more about animal rights in the previous 20 years than