A randomized controlled trial of dexamethasone as an adjunctive therapy to propylene glycol for treatment of hyperketonemia in postpartum dairy cattle

Treatment of hyperketonemia with oral propylene glycol has proven efficacy but the cure rate remains moderate. Dexamethasone has long been suggested as a treatment for hyperketonemia, even though evidence of its efficacy is contradictory. The objective of this randomized controlled trial was to evaluate the effect of adding a single intramuscular injection of 20 mg of dexamethasone to oral propylene glycol therapy for hyperketonemia [blood β-hydroxybutyrate (BHB) ≥1.2 mmol/L]. All cows between 3 and 16 d in milk on 4 dairy farms in New York State were tested once weekly for hyperketonemia using a handheld ketone meter. All enrolled animals received 312 g (300 mL) of propylene glycol orally once daily for 4 d and either a single injection of dexamethasone or an equivalent volume of sterile saline. A total of 509 animals were enrolled, with 254 and 255 in the placebo and dexamethasone groups, respectively. Treatment with dexamethasone decreased the odds of being hyperketonemic in the second week posttreatment; however, the odds of hyperketonemia in the first week posttreatment only decreased in those animals that were treated at a BHB blood concentration between 1.2 and 1.5 mmol/L. For the 8% of cows with blood BHB >3.2 mmol/L at enrollment, receiving dexamethasone increased the odds of being hyperketonemic the following week. We detected no difference between treatment groups in the odds of postpartum disease or in milk production. For cows with initial BHB of 1.2 to 1.5 mmol/L, treatment with dexamethasone tended to reduce the odds of pregnancy at first insemination. Based on the small and conditional benefits of dexamethasone and a lack of difference in milk yield or disease incidence, we do not recommend the use of dexamethasone to treat hyperketonemia.