The importance of the nonlactating period in the epidemiology of intramammary infection and strategies for prevention.

The dry period is a high risk period for the acquisition of new environmental IMIs, with over 60% of new IMIs occurring at this time. It also offers an ideal opportunity to improve udder health, through the judicious use of antibiotics to treat high SCC cows. The prophylactic use of antibiotics in food producing animals is increasingly being called into question; DCT is the primary example of such antibiotic use in the dairy cow. A holistic approach to management of the dry cow is a vital part of mastitis control, and should encompass environmental and nutritional management as well as the blanket use of therapeutic and prophylactic medicinal products. In high SCC cows, it is important to select cows appropriate for treatment (as opposed to culling), and there is a good clinical justification for the use of antibiotics to treat existing IMIs. In low SCC cows, teat sealants provide a viable alternative to antibiotic DCT, and careful consideration should be given to their use.