Just when I was getting smug about being in a great position relative to the genetic resistance of my flock to scrapies – another disease hits my radar. Ovine Progressive Pneumonia (OPP) is much more prevalent and is eventually lethal to all flock members who contract it. It affects the lungs, the joints, and sometimes the nervous system, but symptoms vary widely and often an infected and infectious animal exhibits none of them.
A group at USMARC, a USDA research facility in Nebraska in conjunction with staff at UN-Lincoln have investigated the epidemiology and genetic resistance factors for the disease. They found a gene that they determined affects how the virus penetrates the membrane around living cells. They also found variants in the sequence of this gene that correspond to different levels of susceptibility – there is no absolute resistance known – yet.
Today a vet, her assistant, and I drew blood from the breeding flock to be sent for testing of their 1) genetic resistance profile and 2) whether they have the disease. The first test uses gene sequencing the second uses ELISA to detect the level of antibodies in their blood.
As a responsible breeder it is important to me to know the status of my flock and its members so that I can make appropriate breeding, culling, and marketing decisions. Lambs younger than 7 months do not test reliably for the infection status so I cannot know for certain their condition but can get some indication from their genotype and whether the disease is present in the flock at all, especially in their mothers. The disease is transmitted through milk and colostrum but also through mucus – sneezing and slobber on shared water containers, for instance.
The results should be back in about 2 weeks so I should know in time to decide the best course of action for showing lambs at the Sheep and Fiber Farm Tour on October 11th and 12th.
Whether I’m being paranoid or prudent will only be known in hindsight. Stay tuned for the results. If you care to learn more about OPP, there is a society to raise awareness of it that has a very nicely done and informative website.

http://www.oppsociety.org/Home.html