Six Jersey crossbred cows aged 4–6 years brought to Madras Veterinary College Hospital with history of reduced milk yield formed the basis of this study. A total of 24 quarter milk samples were collected aseptically and examined for the colour, consistency, odour, pH, somatic cell count (SCC), electrical conductivity (EC), modified white side test (MWST) and modified California mastitis test (MCMT) as per standard procedures. The colour, consistency and odour of the subclincial mastitis (SCM) were found to be normal. The subclinical mastitis (SCM) milk pH, SCC, EC, MWST and MCMT were found to be significantly elevated (P<0.01) during the pretreatment stage and these values significantly reduced following single treatment of long acting Inj. Enrofloxacina. In the present study, 100 percent quarter cure was observed and the clinical cases recovered completely from SCM on the fourth day.
