How do I prevent and treat subclinical and clinical ketosis in fresh dairy cows?

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Propylene glycol (PG) is the cornerstone of both prevention and treatment of ketosis in fresh dairy cows, with differentiated protocols based on clinical status and timing of intervention. For prevention, PG is administered at 4–8 fluid ounces (approximately 120–240 mL) per head daily as a drench or feed additive, beginning two weeks before freshening and continuing for six weeks after calving.8 Monensin, available as a sustained-release bolus (Kexxtone), reduces the incidence of ketosis by over 50% and increases milk yield in the first weeks after calving, though its antibiotic nature and cost limit universal application.1 Body condition management during the dry period is fundamental — avoiding excessive subcutaneous fat and abdominal adiposity at parturition reduces the degree of negative energy balance and lipolysis that drives ketone body accumulation.5 For treatment of subclinical ketosis (SCK), PG is administered at 400 g/head/day, and treatment initiated within the first 7 days of lactation achieves a cure rate of 76.5% — substantially higher than treatment begun later in lactation.12 The SCK prevalence in the first 9 days of lactation reaches 41.5% in some herds, making early screening essential to capture the window of highest treatment efficacy.12 PG treatment also improves milk quality parameters and increases milk yield, supporting its economic justification.12 For treatment of clinical ketosis (type I), intravenous glucose combined with oral PG is the recommended protocol; glucocorticoids are avoided in type I ketosis.1 The treatment course for clinical disease is PG at 4–16 fluid ounces (approximately 120–480 mL) per head per day for 10 days as a drench.8 In cows with concurrent fatty liver or abnormal liver function — indicated by serum aspartate aminotransferase (AST) activity above 100 IU/L — standard glucose and PG alone are insufficient, as secondary ketosis with hepatic involvement is difficult to resolve with gluconeogenic precursors alone.14 D