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
Abolitionism (animal rights) forms of animal use, since they believe this undermines the movement to abolish all forms of animal use. The objective is to secure a moral and legal paradigm shift, whereby animals are no longer regarded as things to be owned and used. The American philosopher Tom Regan writes that abolitionists want empty cages, not bigger ones. This is contrasted with animal welfare, which seeks incremental reform, and animal protectionism, which seeks to combine the first principles of abolitionism with an incremental approach, but which is regarded by some abolitionists as another form of welfarism or "New Welfarism". The word relates