Milk and serum concentration of ceftiofur following intramammary infusion in goats.

Abstract

Five dairy goats were used to determine the milk and serum concentrations along with elimination characteristics of ceftiofur following intramammary administration. One udder half of each goat was infused twice with 125mg ceftiofur with a 24-h interval between infusions. Milk samples were collected at 1, 2, 8, and 12h after the last infusion and then every 12h for a total of 7days. Blood was collected from each animal at 3, 8, 12, and 24h after infusion and then every 24h for 6days. Following a washout period of 1week, the experiment was repeated using the opposite udder half. The elimination half-life of ceftiofur from the mammary gland was 4.7h. The concentration of ceftiofur was greater than published MIC90 values for Staphylococcus spp. bacteria for 24h. Ceftiofur was absorbed into systemic circulation from the mammary gland. The maximum concentration was 552ng/mL at 3h after infusion, and the serum elimination half-life was 10h. Intramammary infusion of 125mg ceftiofur every 24h can be expected to maintain drug concentration in milk above published MIC90 for Staphylococcus spp.