Maesfen
Extremely Old Nag!
But in reality is this true? I have 7 horses and can pick up when something is wrong before water consumption drops, in fact in 25 years I don't think water consumption has ever been an indication of a problem.
Couldn't agree more. Plain horsemastership, nothing else; if you haven't spotted the problem before dehydration there is something amiss with your management I'm afraid.