Ketosis is one of the most common metabolic diseases on dairy farms. It occurs when cows have an abnormal response to negative energy balance. After calving, all cows experience some degree of negative energy balance, mobilize body fat for the additional energy needed for milk production and lose weight during the first several months of lactation. But, if cows mobilize excessive amounts of fat, the metabolic process of converting this fat to energy can result in an undesirable buildup of ketones in the bloodstream.
Watch for the following clinical signs: decreased milk production, poor appetite, decreased rumen fill, dehydration, sunken eyes and constipation. In severe cases, known as nervous ketosis, cows will exhibit neurologic signs such as weakness, running into walls, or compulsive licking/chewing.
Cow-side diagnostic tests
If you suspect ketosis, you have several options to help confirm the diagnosis.
1. Urine test strips. Once the cow urinates, hold the ketone strip into the urine and watch for a color change (purple) which often occurs within seconds. The urine strips are the least costly test; however, they do miss some cows with ketosis (due to lower sensitivity).
2. Milk Ketone Test strips. The milk test strips measure the amount of beta hydroxybutyrate (BHBA) in the milk which is the primary cow ketone. This test is more costly than the urine strip, but it is more sensitive than that test. Squirt milk into a clean container, dip in the strip for the manufacturer’s recommended amount of time, then compare the color change to the code on the bottle.
3. Precision Extra Blood BHBA meter. This is the most sensitive ketosis cow-side test. This meter is a human diabetic meter that measures ketones as well as glucose levels. Insert the strip into the machine, place a drop of blood and you’ll get an actual number of BHBA in the cow. Normal is less than 1.3. The advantage of the blood meter is high sensitivity, accuracy of a number versus a color change, economics (about $1.50 per test) and the ability to detect subclinical ketosis.
Any sick fresh cow should be tested for ketosis. Use the urine test first. If positive, then treat for ketosis. If negative, confirm with a blood or milk ketone test. Consider testing all fresh cows for ketosis at three to seven days fresh with the blood BHBA meter. This allows you to detect subclinical ketosis cows so you can intervene at the herd level and prevent cases. It also allows for earlier treatment, as well as evaluating the ability of the management team to detect cows with ketosis. If a cow is high on the BHBA meter and nobody knows she has ketosis, then you need to improve your ability to find sick cows.