Ketosis

What is Ketosis?

Ketosis is a metabolic disorder that occurs when a cow's energy demands (for milk production) exceed her energy intake, causing the body to mobilize body fat for energy. This fat mobilization produces ketone bodies (beta-hydroxybutyrate, acetone, acetoacetate) that accumulate in the blood, urine, and milk.

Ketosis typically occurs in early lactation (3–14 DIM) when milk production rises rapidly but dry matter intake hasn't caught up. Risk factors include: obesity at calving (BCS >7), poor transition cow nutrition, low-fiber rations, and any condition that reduces feed intake (lameness, mastitis, DA).

Clinical ketosis shows signs of: reduced appetite, decreased milk production (5–10 lbs/day), sweet/fruity breath odor (from acetone), neurological signs (star-gazing, tongue-rolling) in severe cases. Subclinical ketosis — elevated BHB without visible signs — affects 15–30% of fresh cows and is detected by testing milk or blood ketone levels.

Treatment involves oral or intravenous glucose supplementation (propylene glycol, dextrose), while prevention focuses on proper body condition management (calving at BCS 5–6), gradual feed transition, and providing high-energy rations during the last 3 weeks before calving.

Subclinical vs Clinical Ketosis

Subclinical ketosis is defined by blood BHB levels of 1.2–3.0 mmol/L with no visible clinical signs. It affects 15–30% of fresh cows and costs $50–$100 per case in lost production due to reduced milk yield, impaired fertility, and increased susceptibility to other diseases. Subclinical cases are detected only through routine testing — visual observation misses them entirely. Clinical ketosis presents with blood BHB >3.0 mmol/L and obvious neurological signs: reduced appetite, decreased milk production (5–10 lbs/day), sweet or fruity breath odor from acetone, star-gazing, and tongue-rolling in severe cases. Clinical cases cost $200–$400 per case when factoring in treatment, lost production, and secondary complications. Herds with >15% subclinical prevalence should re-evaluate transition cow management, body condition scoring, and fresh cow nutrition protocols.

Ketosis Testing Protocol

Test all cows at 3–14 days in milk (DIM) using a cowside BHB (beta-hydroxybutyrate) test. Blood BHB >1.2 mmol/L indicates subclinical ketosis. Milk BHB >0.15 mmol/L indicates subclinical ketosis. Urine ketone strips (measuring acetoacetate) are less accurate but useful for initial screening. Establish a weekly testing schedule during the fresh period — test every cow on Days 3, 7, and 14 post-calving. Record results and track prevalence monthly. If prevalence exceeds 15%, investigate transition cow nutrition (dry cow feed, close-up pen management) and body condition at calving. Portable BHB meters (e.g., Precision Xtra, PortaBHB) cost $50–$150 and provide results in 30 seconds. Milk ketone test strips cost $0.50–$1.00 per test. Budget $200–$400/year for a 100-cow herd — the cost is recovered many times over through early detection and prevention.

Treatment Algorithms

Mild cases (subclinical or minimal signs): oral propylene glycol 200 mL twice daily for 5 days. Propylene glycol is a glucose precursor that raises blood glucose and suppresses fat mobilization. Administer at the same time each day, ideally in the morning before feeding. Moderate cases (visible signs but still standing): IV 500 mL of 50% dextrose solution administered slowly over 10–15 minutes. Follow with oral propylene glycol for 5 days. Monitor blood BHB at 24 and 72 hours post-treatment — BHB should drop below 1.0 mmol/L. Severe cases (down cow or severe neurological signs): repeat IV dextrose every 8–12 hours as needed, treat secondary conditions (displaced abomasum, mastitis, metritis), provide supportive care (colostrum tubing, anti-inflammatory drugs), and ensure adequate bunk access. Always address the underlying cause — if >10% of fresh cows are ketotic, review the transition ration and dry cow feeding program.