Ovine pulmonary adenocarcinoma as an animal model for human lung cancer, because OPA is histologically similar to human adenocarcinoma in situ of the lung. Dolly the sheep, the first mammal successfully cloned from an adult somatic cell, was euthanized after it was confirmed that she had OPA. 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
Alternatives to animal testing Medical Experiments that despite the use of microdosing, "animal studies will still be required". Guiding principles for more ethical use of animals in testing are the Three Rs (3Rs) first described by Russell and Burch in 1959. These principles are now followed in many testing establishments worldwide. Cell culture can be an alternative to animal use in some cases. For example, cultured cells have been developed to create monoclonal antibodies; prior to this, production required animals to undergo a procedure likely to cause pain and distress. However, even though cell or tissue culture methods may reduce the number of experiments