Looking back on it, it all seems pretty obvious now. Of course the problem in my flock was Ovine Progressive Pneumonia (OPP). I have had sheep with just about all the symptoms, but it took me a few years to notice it and a few more to figure out how to deal with it.
The parasites that infest sheep can be an enormous drag on sheep production. Year in and year out, they probably cause more death and disease in some producers’ lamb crops than any other single factor, including predators.