Influence of mastitis on milk production, somatic cell count, and concentrations of sodium, potassium and lactose in bovine milk. Milk production, somatic cell count, and concentrations of sodium, potassium and lactose of 32 pairs of normal equivalent quarters as well as 54 pairs of equivalent quarters, in the case of which one quarter was affected with subclinical mastitis, were investigated. Affected quarters showed a definite decrease in milk production, lactose and potassium content. The mastitis quarters showed an increase in the somatic cell count and sodium content.