Targeted Drug Delivery to Mammary Gland Using Liposomal Encapsulation for Subclinical Mastitis Treatment in Dairy Cows in Kano State

Subclinical mastitis causes substantial economic losses in Nigerian dairy production by reducing milk yield and quality without presenting overt clinical signs, making early and effective treatment challenging. Conventional intramammary antibiotic infusions achieve limited distribution to deep mammary parenchymal tissue and the intracellular compartment where Staphylococcus aureus persists. Liposomal drug delivery systems offer a strategy to enhance mammary parenchymal drug distribution, prolong local drug residence, and improve intracellular antibiotic delivery against persistent pathogens. This study developed, characterised, and evaluated cloxacillin-loaded liposomes for intramammary delivery against subclinical mastitis caused by Staphylococcus aureus in dairy cows in Kano State, North West Nigeria. Liposomal formulations were prepared by thin-film hydration with DPPC and cholesterol in a 7:3 molar ratio, characterised for size, zeta potential, encapsulation efficiency, and in vitro drug release. Comparative mammary pharmacokinetic and pharmacodynamic studies were conducted in 30 Holstein Friesian crossbred cows with California Mastitis Test-confirmed subclinical mastitis randomly allocated to conventional cloxacillin infusion, liposomal cloxacillin at equivalent dose, and negative control groups. Mammary tissue cloxacillin concentrations were determined by HPLC from biopsies at 12, 24, and 48 hours. Bacteriological cure rate at 14 days was the primary pharmacodynamic endpoint. Liposomal formulations achieved significantly higher mammary parenchymal cloxacillin concentrations at 24 and 48 hours compared with conventional infusion. Bacteriological cure rate was 76.7 percent for liposomal versus 53.3 percent for conventional formulation. These findings validate liposomal intramammary drug delivery as a superior approach for subclinical mastitis management in Nigerian dairy herds and advance a practical nanotechnology application for Nigerian veterinary therapeutics. Keywords: liposomal delivery, mastitis, cloxacillin, dairy cattle, Kano.