Oregon wildlife officials are investigating the first known cases of a pneumonia-causing respiratory pathogen in the John Day River bighorn sheep herd.  The Oregon Department of Fish and Wildlife says several California bighorn sheep recently tested positive for Mycoplasma ovipneumoniae, or M. ovi.  The John Day herd is Oregon’s largest, with an estimated one-thousand sheep.  ODFW is testing dead animals and surveying the canyon for additional sick sheep to determine how widespread the disease is.  There is no known vaccine or treatment.   Officials say contact with domestic sheep and goats, as well as exotic aoudad, can spread the pathogen.  ODFW is working with tribal and other partners to develop a management plan.  Anyone who finds a dead or sick bighorn sheep in the John Day River canyon is asked to contact ODFW.