Most horse owners know they need a Coggins test before trailering their horse and heading to a show or another state. But some may not know the purpose of the test.

Over the past 40 years, this U.S.-based testing has identified more than 100,000 cases of equine infectious anemia, a deadly viral disease. But is the Coggins test now a victim of its own success?

Because of this testing and efforts to stop the disease from spreading, fewer than 100 new cases have been reported in the past two years. With 4 million horses tested, this success comes at a cost of about 1 million dollars per positive. Such diminishing returns have caused some scientists to advocate for new strategies using fewer and less expensive tests.

Change is coming gradually, on a state-by-state basis, so check with your vet or extension service about current rules before you and Mister Ed hit the road.