Review/Oorsig Volume 22, Issue 02 - Page 33

Volume 22 • Issue 02 • 2018 If more than one approach to disease prevention is used effectively in combination, up to a 100% of a vaccinated herd can be protected. It must still be appreciated that there is a large variation between the prevention approaches needed for all the different diseases that affect dairy animals. Some industry specific disease like claw infections will always occur, but need to be managed in such a way that as not to exceed a set limit. Disease Prevention Strategies In most instances more than one approach to disease prevention must be employed in order to effectively control a disease, especially in a dairy herd that needs to produce on a daily basis. Controlling a very complex disease like Staphylococcus areus mastitis in a herd is such an example. 1. Firstly the general disease resistan ce must be improved by good parasite control and good nutritional management, especially during the dry period and after calving. On its own, this approach cannot control the spread of this infectious form of mastitis. 2. Secondly the specific resistance against this disease-causing organism must be stimulated. This was not possible before but with a new effective vaccine on the market, this is possible. 3. Thirdly the level of exposure must be decreased through identification and culling of chronically affected carrier animals and the use of effective dry cow mastitis remedies where prescribed by the herd veterinarian. Prevent Disease Exposure The fourth and final approach to disease prevention is to prevent exposure completely. This is most important in the case of diseases for which there are no vaccines, no treatment available, or where the herd is currently free of this disease. Most of our state controlled diseases can be named as examples: • • Bovine tuberculosis Foot and mouth disease (controlled without vaccination in the disease-free area of South Africa) Certain uncontrolled diseases from which the herd is currently free must also be prevented by this approach, for example Johne’s disease. In this case a large part of the herd is very susceptible, either because the animals were never exposed to this disease, or because no vaccination is available to increase the specific resistance of the animals. General resistance will not protect all the animals in the herd against these diseases if new animals are introduced into the herd. 33