Management of the dry cow in control of peripartum disease and mastitis

The importance of the dry period, with respect to udder health, productivity, and overall health in the next lactation, has been well documented [1-6]. In the absence of effective mastitis prevention and control measures, more quarters of the udder will be infected at calving than at dry-off. This change in prevalence of intramammary infections (IMI) over the dry period is a result of a failure to eliminate existing infections and prevent development of new ones [1]. Of these two aspects, improvement in udder health can be achieved more readily with emphasis placed on preventing new infections. This approach also offers greater long-term benefits to the dairy producer [1]. At present, administration of intramammary dry-cow antibiotic therapy (DCT) at the end of lactation is the most effective means of eliminating existing infections and preventing new ones [1]. Other than the recommendation to treat all quarters of all cows at dry-off, however, guidelines for managing dairy cows from the 2 weeks prior until the 2 weeks following dry-off are not well established. Furthermore, the need to address shortcomings and concerns over prophylactic antibiotic use and an increased awareness of the late dry period as a time of great metabolic and immunologic challenge for the cow and udder have prompted the search for new management strategies. This-article highlights the importance of dry-period management, with respect to maintaining udder health and minimizing periparturient disease. Emphasis is placed on describing the epidemiology and impact of new IMI and on factors that influence the susceptibility of cows and quarters to develop these infections.