It is tested by way of a urine sample Pat.
Interesting between race interview on Racing.com with gallops trainer John Leek just now
He has a positive to cobalt awaiting adjudication
He said that he had a horse test with a 203 reading while another just got under with 190
He said that prior to this he did not know what cobalt was
He said that when his horses are in serious work they are fed Hygain and he now knows that cobalt is listed on the bag
He said that nearing racing his horses are given B12 injections and that he did not know that there is cobalt in them
Most interesting insight for me was that he said in the fortnight leading up to a horse racing they would be given a vitamin injection every 2nd day