Ketosis in Dairy Animals: BHB and NEFA Tests

Ketosis happens when a dairy animal burns too much of her own body fat for energy, most often in the weeks around calving. Blood tests for BHB and NEFA, and a ketone test on milk, can help a vet find it, even before the signs are clear. Finding it early protects the animal's health and her milk.

Why does ketosis happen around calving?

Late in pregnancy and just after calving, a cow or buffalo needs far more energy than she can eat. Milk production climbs faster than appetite. To fill the gap, the body breaks down stored fat. The liver turns part of that fat into substances called ketones, and when too many build up, the animal becomes ill. Heavy milkers, animals that were too fat before calving and animals that stopped eating because of another illness are the most likely to be affected.

What signs may you notice?

Some animals show clear signs, and many show none at all. When there are signs, they can include:

• a poor appetite, often for grain first
• a fall in milk yield
• weight loss and a dull coat
• dullness, or in some animals odd behaviour
• a sweetish smell on the breath or in the milk

These signs also come with other illnesses such as womb infection, mastitis or a displaced stomach, so a vet's examination matters. Ketosis without signs is called subclinical, and it still costs milk and slows recovery, which is why testing is useful.

Which tests help?

Several tests are used together or one after another.

• The Beta-hydroxybutyrate (BHB) - Blood Ketones measures BHB, the main ketone in blood. It is the usual test for ketosis.
• The NEFA (Non-Esterified Fatty Acids) measures fatty acids released from body fat, and shows how hard the animal is drawing on her reserves.
• The Milk BHB (Ketosis) Test looks for ketone in milk, which can be easier to collect.
• A Glucose Random (RBS) shows the blood sugar, which is often low in ketosis, although not always.

The lab report shows the reference range and the lab quotes no cut-off numbers. A registered veterinarian reads the result together with the animal's signs, feeding and stage of lactation. The lab confirms the sample needs and the reporting time when you book.

When is the right moment to test?

Your vet will tell you which animals to test and when. Often it is animals close to calving and in early lactation, animals that are eating poorly or giving less milk than expected, and animals in a herd with repeated cases. Testing a few animals in each group gives a picture of the whole herd.

What happens after a positive result?

Your vet decides what to do for the animal and may look at feeding and management in the herd. The lab gives no feeding or treatment advice. Ketosis often travels with other problems, such as a womb infection, mastitis or a stomach that has moved out of place, so the vet may look for those as well. Records help: note which animals were affected, how soon after calving, and how the herd was fed in the weeks before. A repeat test after a while shows whether things are improving, and a herd with many cases may need its feeding plan reviewed by the vet or a nutritionist. The Transition Cow Metabolic Pack groups BHB, NEFA, minerals and blood sugar for the weeks around calving.

How do you collect the sample?

Blood is usually drawn by the vet from a vein into the tube the lab names, and kept cool. Milk should be collected into a clean, lidded container and labelled with the animal's number and the time. Fresh samples give the most reliable readings.

Read next

Blood sugar matters in people's pets as well, and the same ideas are explained in Diabetes in Dogs and Cats: Glucose, Fructosamine and HbA1c. If an animal needs an operation, see Pre-Surgical Blood Tests: The Pre-Anaesthetic Panel Explained.

Testing in Bhopal

Your vet usually takes the sample, and the lab at C-200, C Sector, Shahpura, Bhopal accepts it. Collection is free anywhere in Bhopal, and other districts can use courier, bus parcel or their vet. Call or WhatsApp +91 88175 01118; the lab confirms the method, sample needs and reporting time when you book.