Ovine pulmonary adenocarcinoma Ovine pulmonary adenocarcinoma Ovine pulmonary adenocarcinoma (OPA), also known as ovine pulmonary adenomatosis, or jaagsiekte, is a chronic and contagious disease of the lungs of sheep and goats. OPA is caused by a retrovirus called jaagsiekte sheep retrovirus (JSRV). The disease has a long incubation period, and therefore signs usually occur in adult animals (over 2 years of age). Clinical signs resemble a non-specific progressive pneumonia, including poor body condition and, particularly after exercise, respiratory difficulty. Unless a concurrent lung infection is present, affected sheep continue to eat. The only sign specific to OPA is a watery nasal discharge, consisting
Animal welfare in the United States Animal welfare in the United States Animal welfare in the United States relates to the treatment of non-human animals in fields such as agriculture, hunting, medical testing and the domestic ownership of animals. It is distinct from animal conservation. The first known animal welfare laws in North America were regulations against "Tirranny or Crueltie" toward domestic animals included in the 1641 Massachusetts Body of Liberties. Starting in the late 1820s, a number of states passed anti-cruelty statutes. Many of these exempted animals used in experiments, and only twice were they invoked on behalf of animals. The first Humane Societies and