Miller Ranee A, Smith Geof W, Halleran Jennifer L, Foster Derek M, Baynes Ronald E
Department of Population Health and Pathobiology, Center of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, USA.
J Vet Pharmacol Ther. 2025 Apr 21. doi: 10.1111/jvp.13512.
Mastitis is the most burdensome concern for the dairy cattle industry. Antimicrobials are often prophylactically administered to dairy cows at dry-off to reduce the risk of intramammary infection during the dry period and subsequent lactation. Mastitis incidence has increased in dairy heifers after calving, leading to extralabel drug use of various dry cow products, including intramammary ceftiofur hydrochloride. However, the pharmacokinetics and efficacy of this application have yet to be studied. This study aimed to compare the pharmacokinetics and efficacy following no treatment, a non-antimicrobial teat sealant, or a single dose of intramammary ceftiofur given at 21 or 14 days before expected calving. We hypothesized that milk collected following dosing would contain drug residues below the FDA tolerance of 100 ng/mL by calving, and heifers within the ceftiofur treatment groups would have lower somatic cell counts (SCCs) than heifers in the teat sealant and nontreatment control groups. Following treatment or no treatment of 24 prepartum heifers, milk samples were collected until 21 days after calving. Somatic cell counts and ceftiofur concentrations were assessed utilizing a cell counter and UPLC/MS detection, respectively. Ceftiofur administration did not significantly reduce SCCs compared to other groups by days 7, 14, or 21. For heifers treated 14 and 21 days prior to calving, milk had a maximum ceftiofur concentration of 8.14 ± 6.24 and 4.20 ± 5.07 ng/mL 48 h into lactation, respectively. The minimal ceftiofur concentrations in milk collected from these heifers indicate that administration of ceftiofur 14 or 21 days before calving is unlikely to lead to violative residues. However, it is essential that regional regulations regarding the use of ceftiofur are adhered to.
乳腺炎是奶牛养殖业最令人担忧的问题。在奶牛干奶期，常预防性地给奶牛使用抗菌药物，以降低干奶期及随后泌乳期乳房内感染的风险。产犊后，小母牛的乳腺炎发病率有所上升，导致包括乳房内注射盐酸头孢噻呋在内的各种干奶牛产品出现超说明书用药的情况。然而，这种应用的药代动力学和疗效尚未得到研究。本研究旨在比较在预期产犊前21天或14天不进行治疗、使用非抗菌乳头密封剂或单剂量乳房内注射头孢噻呋后的药代动力学和疗效。我们假设，给药后采集的牛奶在产犊时药物残留量低于美国食品药品监督管理局（FDA）规定的100纳克/毫升的耐受量，并且头孢噻呋治疗组的小母牛体细胞计数（SCC）低于乳头密封剂组和未治疗对照组的小母牛。对24头产前小母牛进行治疗或不治疗后，采集牛奶样本直至产犊后21天。分别使用细胞计数器和超高效液相色谱/质谱检测法评估体细胞计数和头孢噻呋浓度。与其他组相比，在第7天、14天或21天时，头孢噻呋给药并未显著降低SCC。对于在产犊前14天和21天接受治疗的小母牛，泌乳48小时时牛奶中头孢噻呋的最大浓度分别为8.14±6.24和4.20±5.07纳克/毫升。从这些小母牛采集的牛奶中头孢噻呋的最低浓度表明，在产犊前14天或21天注射头孢噻呋不太可能导致违规残留。然而，必须遵守关于头孢噻呋使用的地区规定。
