Colorado? One of those was confirmed dirty needle from the Texas outbreak. The other hasn’t had a source identified and they have quarantined horses it was in contact with. It’s hard to say what the real risk is in terms of the general horse population but requiring Coggins seems like common sense under the circumstances even if you are not crossing state lines. EIA has popped up often enough in wild horse herds that an untraced case is concerning.
People need to remember how much bigger the west is, crossing state lines to show isn’t particularly common. I know people who’ve been showing for 40 years in CA and never gone out of state with a horse. When all horses need a negative test to enter the state the risk at a local show under normal circumstances is very, very close to zero and history bears that out. The occasional positive test is usually very quickly traced, typically to medical cause or horses being smuggled across borders.
An untraced positive result in a domestic horse out west is pretty unusual. I can’t remember the last time I heard of one tbh.