A breath test for spotting ketosis is not accurate. “You may miss up to 80 percent of cows with clinical ketosis,” says Sheila McGuirk, veterinarian at the
Instead, use a urine test or milk test to detect ketones. The cost of a urine test is only a few cents per cow, so try that first, McGuirk says. If you can’t get urine, use a milk-ketone test. It’s more expensive — about $2 per cow — but, if the test is positive, you can be sure that she has ketosis.