The objectives of this work were to analyze and to quantify the influence of the production scale on the economic impact of mastitis in dairy cattle herds. The study was conducted through a simulation in the computer system 'CU$TO MASTITE' ('MASTITIS CO$T'), considering dairy cattle with 50; 100 and 150 lactating cows. Monitoring expenses (culture and antibiogram, CCST and CCSI), pre and post dipping, vaccination, treatment of dry cows and milking maintenance, were considered as prevention. The treatments with clinical cases, which had a 7% percentage of lactating cows were considered as curative measures. The impact of mastitis was estimated as the total of losses plus expenses with prevention and the treatments of clinical cases. The increase of the production scale resulted in a lower economic impact of mastitis per lactating cow. When the effect of the production scale was analyzed, the losses with milk disposal, curative treatment of clinically affectedanimals and a decrease in milk production were the factors that most affected the economic impact, in a descending order. Expenses with preventive treatment accounted for, at maximum, 11.7% of the economic impact, which demonstrates advantages of investing on that practice because it will contribute significantly for the reduction of the economic impact caused by mastitis
animal health; dairy cattle; economy
