Iodine in Milk and Serum Following Intrauterine Infusion of Lugol’s Solution

Due to their low cost, proven effectiveness, and lack of withholding time for milk and meat products, iodine solutions have been a popular choice in the treatment of dairy cow uterine abnormalities for over 50 years. This study was aimed at determining the quantity of iodine appearing in milk following the intrauterine administration of 60 mL of a 10% Lugol’s solution. Two groups of 6 cycling, reproductively normal, Holstein cows under similar management and feeding programs were used. The infusions occurred in both groups on Days 1, 10, 20, 30, 40, and 50 postpartum. Control animals were infused with 60 mL physiological saline. Milk and serum iodide concentrations were measured using a double-junction reference electrode (Ag/AgCl) and an iodide/cyanide specific electrode (I-/CN). Serum pH was determined using a Corning pH/ion meter (Model 150). There appeared to be no trend between days postpartum and percent of intrauterine iodine excreted via the mammary gland. The mean half-life of iodine of all cows at all infusions was 48.4 hours, with a standard deviation of 19.0 hours. No statistically significant difference was found for iodide clearance rates from the mammary gland as a function of postpartum. Eighty-nine percent of all peak serum iodine concentrations occurred within 30 minutes of infusion of intrauterine Lugol’s solution. Significant concentrations of milk iodide persisted in Lugol’s treated cows throughout each 10-day infusion period when compared with the saline-infused group, such that no explicit recommendation for withholding due to excessive milk iodide could be made. The use of iodine-containing preparations for intrauterine infusions should be used with caution as excessive iodine content of milk could reach market.