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 Animal welfare Animal welfare is the well-being of nonhuman animals. The standards of "good" animal welfare vary considerably between different contexts. These standards are under constant review and are debated, created and revised by animal welfare groups, legislators and academics worldwide. Animal welfare science uses various measures, such as longevity, disease, immunosuppression, behavior, physiology, and reproduction, although there is debate about which of these indicators provide the best information. Respect for animal welfare is often based on the belief that nonhuman animals are sentient and that consideration should be given to their well-being or suffering, especially when they are under