People freak out about a horse without a Coggins test or even no vaccination history.
I always find that bizarre. A Coggins, a vaccination record, and a health certificate are no guarantee of anything.
As mentioned earlier, a Coggins is merely a piece of paper reporting the results of a blood test that was possibly sampled months earlier. It is not a guarantee of health, it’s not even a guarantee the horse hasn’t been exposed to EIA in the time since sampling.
Of the AAEP core vaccines, none of them are directly transmissible from horse to horse. All of them are acquired via another means. (You may be able to argue Rabies could be passed from horse to horse, but that would be an extremely unlikely scenario.) The diseases that are passed from horse to horse, like flu, strangles, rhino, salmonella, etc., either are considered “optional” vaccinations by many or don’t have an effective vaccine.
Even health certificates are not foolproof-- just look at the cluster that occurred in New Mexico earlier this year with EHV-1. Horses with all the appropriate paperwork carried the disease from racetrack to racetrack thanks to poor handling and communication from the management.
If there is any question about a horse’s health or exposure to disease, quarantine is always the best route. Otherwise, I don’t see the sense in getting bent out of shape about what paperwork the horse does or does not have.
As for transporting without one, unless you are going to or through a specific destination that requires the paperwork to be shown, I find it hard to believe there would be any issue on local roads. Not encouraging folks to travel against the law, just saying I can’t imagine encountering an issue on a local run.