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 movement idealistic and schismatic. These reform-oriented nonhuman rights organizations direct resources to countering abolitionist claims and blocking abolitionists' access to discursive spheres. Another example of counterframing from opposition movement actors is found in Switzerland's 1998 referendum cycle, in which antivivisectionists' claims that animal research should be abolished were contested with claims that mobilized the public more. Antivivisection claims, which framed animal research as facilitating the genetic engineering of foods in hopes of seizing on public fear of genetic engineering, were countered by scientists and animal researchers, who framed vivisection as medically necessary to ensure human well-being. Animal rights movement The animal