Ketosis in cows is a metabolic disorder where a dairy cow’s body breaks down its own fat reserves too quickly, flooding the bloodstream with ketone bodies. It happens most often in the first few weeks after calving, when the energy demands of milk production outstrip what the cow can take in through feed. It is one of the most common and costly metabolic problems in dairy farming.
Why Ketosis Happens After Calving
A dairy cow at peak milk production needs enormous amounts of glucose, mostly to produce lactose in milk. In the days and weeks after calving, her appetite hasn’t caught up with what she’s burning. This gap between energy in and energy out is called negative energy balance, and every dairy cow experiences it to some degree.
When the deficit is large enough, the cow’s body mobilizes fat from its reserves to make up the difference. The liver processes these fatty acids, but when they arrive faster than the liver can convert them to usable energy, a portion gets turned into ketone bodies instead. Small amounts of ketones are normal and can be used as fuel. The problem starts when ketone levels climb high enough to suppress appetite further, creating a vicious cycle: the cow eats less, mobilizes more fat, and produces even more ketones.
Type I vs. Type II Ketosis
Ketosis isn’t a single condition. Two distinct forms are recognized, and they differ in timing, cause, and how the cow’s body responds.
Type I (classic ketosis) typically shows up 2 to 6 weeks after calving, right around peak milk yield. The cow simply can’t eat enough to fuel her production. Blood sugar drops because the liver can’t manufacture glucose fast enough, and ketone levels spike. This is the straightforward “too much output, not enough input” form.
Type II (fatty liver ketosis) appears earlier, usually within the first 1 to 2 weeks after calving. It’s linked to cows that were overconditioned (too fat) going into calving. These cows accumulate excessive fat in the liver, which impairs liver function. Their blood sugar may actually be normal or even high because they develop a form of insulin resistance, similar in concept to Type 2 diabetes in humans. The liver simply can’t process fat properly. Type II is harder to treat because the root problem is organ dysfunction, not just a calorie gap.
Signs to Watch For
Subclinical ketosis has no visible symptoms at all, which makes it especially dangerous. The cow looks fine but is already losing production and becoming vulnerable to other diseases. The only way to catch it is through testing.
When ketosis progresses to a clinical stage, the signs develop in a recognizable pattern. Early on, a cow will start refusing grain and concentrates while still eating hay or forage. She may eat unusual things like sand or pebbles. Movement becomes reluctant and her gait looks unsteady.
As the condition worsens, appetite drops significantly. The cow becomes dull and apathetic, loses weight, and holds her head low with eyes half-closed, almost dozing. Her breath and urine take on a distinctive sweet, fruity smell of acetone. Feces become hard, dry, and coated with mucus. Milk yield falls noticeably. One telling change in the milk itself: fat content climbs above 5% while protein drops below 2.9%, a ratio shift that bulk tank monitoring can sometimes catch.
In severe cases, a cow may develop what’s called nervous ketosis. She moves forward without purpose, has seizures, salivates excessively, and becomes hypersensitive to noise and touch. She may dip her muzzle into the water trough and loudly mouth at the water without actually drinking.
How Ketosis Is Detected
The gold standard is measuring the ketone body BHB (beta-hydroxybutyrate) in blood. The most commonly used thresholds for subclinical ketosis are BHB levels of 1.0, 1.2, or 1.4 mmol/L, depending on the study and the specific health outcome being predicted. Levels at or above 0.9 mmol/L already begin to affect cow health and performance.
Handheld blood meters designed for cowside use provide fast results and are widely used on farms. Milk and urine test strips exist but are less reliable. A milk test for the ketone acetoacetate is highly specific (99%), meaning a positive result is almost certainly real, but it misses more than half of affected cows (only 41% sensitive). Urine strips perform somewhat better, catching about 78% of cases at a lower threshold, but still miss roughly one in five subclinical cows. For systematic herd screening, blood testing remains the most dependable option.
Linked Health Problems
Ketosis rarely travels alone. Cows with elevated ketones are significantly more likely to develop displaced abomasum, a condition where one of the stomach compartments shifts out of position and often requires surgical correction. Research from the Journal of the American Veterinary Medical Association found a strong association between the two conditions, with ketotic cows having roughly 3 to 25 times the odds of a displaced abomasum compared to healthy cows.
Ketosis also increases the risk of uterine infections (metritis) and mastitis, and it impairs reproductive performance. Cows that go through a bout of ketosis take longer to conceive and are more likely to be culled. The financial toll varies widely depending on severity and herd circumstances. A systematic review of 10 studies found the estimated cost per case ranging from €19 to €812, with farm-level costs estimated at €3.6 to €29 per cow per year across the herd.
Treatment
The immediate goal of treatment is to restore blood sugar and bring ketone levels down. For Type I ketosis, the standard approach is an oral drench of propylene glycol, a syrupy liquid that the cow’s liver converts into glucose. The typical dose is 250 to 400 grams per cow once daily for 3 to 5 days, with milder cases needing only 3 days and severe cases the full 5. In more serious situations, a veterinarian may administer an intravenous glucose solution (a 500 mL bolus of 50% dextrose), though this provides only a short-term spike in blood sugar and doesn’t change the overall course of the disease on its own. Vitamin B12 supplementation is often added to help the cow’s liver process nutrients more efficiently.
Type II ketosis requires a different emphasis. Because the underlying problem is a fatty, poorly functioning liver, treatment goes beyond simply providing glucose. Supplements that help the liver export fat, particularly choline and methionine in rumen-protected forms, are important additions. Managing insulin resistance and limiting further fat mobilization are also priorities. Identifying high-risk cows early, before the liver becomes severely compromised, makes a substantial difference in outcomes.
Prevention Through Transition Management
Prevention starts months before calving, during the dry period. The single most important factor is body condition at calving. Cows should arrive at calving with a body condition score between 3.0 and 3.5 on a 5-point scale. Cows that calve above 3.5 to 4.0 are at much higher risk for Type II ketosis because they’ve stored excessive fat that the liver will struggle to handle. During the dry period, the base ration should be limited to about 75 to 80% of full nutritional standards, with added fiber from straw to prevent overcondition.
In the final 3 weeks before calving (the close-up period), the diet should gradually shift toward what the cow will eat after calving. Adding 0.5 to 3 kg of concentrate feed before calving helps the rumen adapt. Silage containing butyric acid should be avoided, as butyric acid is itself a ketone precursor that adds to the metabolic load. Adequate cobalt, niacin, and B vitamins in close-up diets support the metabolic pathways the cow will need most after calving.
For herds with a known ketosis problem, oral glucose precursors like propylene glycol, glycerin, or calcium propionate can be given preventively starting 7 to 10 days before expected calving and continuing for up to 2 weeks afterward. Typical preventive doses are 250 to 300 grams per day before calving, increasing to 300 to 350 grams per day after. In regions where it’s approved, a slow-release monensin capsule placed in the rumen 3 to 4 weeks before calving has been shown to reduce ketosis incidence by improving the cow’s ability to produce glucose from feed.
After calving, the priority is maximizing feed intake without abrupt diet changes. Consistent, well-balanced rations with adequate energy density help the cow close the energy gap faster. Weekly monitoring of body condition and periodic blood BHB testing of fresh cows, especially multiparous cows in the first three weeks of lactation, allow early intervention before subclinical ketosis escalates into a clinical case with cascading health consequences.