Jaagsiekte sheep retrovirus Jaagsiekte sheep retrovirus Jaagsiekte sheep retrovirus (JSRV) is a betaretrovirus which is the causative agent of a contagious lung cancer in sheep, called ovine pulmonary adenocarcinoma. JSRV is the virus that is the cause of the contagious lung tumors in sheep called ovine pulmonary adenocarcinoma (OPA). The disease has also been called "jaagsiekte", after the Afrikaans words for "chase" ("jaag") and "sickness" ("siekte"), to describe the respiratory distress observed in an animal out of breath from being chased, indicating the breathing difficulty experienced by infected sheep. Transmission of virus is through aerosol spread between sheep. The exogenous infectious form of
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