Several European countries have initiated national and regional control-and-eradication campaigns for bovine viral diarrhea virus (BVDV). Most of these campaigns do not involve the use of vaccines; in Germany, vaccination is used only in states in which it is considered necessary because of high BVDV prevalence. In European countries without organized BVDV control programs, vaccination is commonly used to control BVDV. Diagnostic test strategies are fundamental to all control-and-eradication campaigns; therefore, the purpose of this review is to describe how the available diagnostic tests are combined into test strategies in the various phases of control-and-eradication campaigns in Europe. Laboratory techniques are available for BVDV diagnosis at the individual animal level and at the herd level. These are strategically used to achieve 3 main objectives: 1) initial tests to classify herd status, 2) follow-up tests to identify individual BVDV-infected animals in infected herds, and 3) continued monitoring to confirm BVDV-free status. For each objective or phase, the validity of the diagnostic tests depends on the mode of BVDV introduction and duration of infection in test-positive herds, and on how long noninfected herds have been clear of BVDV. Therefore, the various herd-level diagnostic tools—such as antibody detection in bulk milk or in blood samples from young stock animals, or BVDV detection in bulk milk—need to be combined appropriately to obtain effective strategies at low cost. If the individual diagnostic tests are used with due consideration of the objectives of a specific phase of a BVDV control program, they are effective tools for controlling and eradicating BVDV in regions not using vaccination and where vaccination is a part of the control or eradication program.

A qualitative research study was conducted to describe and analyze farmers' perspectives on their own choices regarding decisions to have cows treated for mastitis. Through qualitative research interviews of 16 Danish dairy farmers, four levels of the decision-making process used by farmers to decide whether or not to treat a cow with antibiotics were identified. Those levels were: 1) symptom level (seriousness of the mastitis case), 2) cow level (to the extent a cow fulfilled goals of the farmer and the herd), 3) herd level (the situation of the herd, e.g., in relation to milk quota), and 4) level of alternatives (whether the farmer regards such practices as blinding of teats or homoeopathy as serious alternatives to antibiotic treatment). All four levels could be recognized in all herds, but with differing weights and relative importance across herds. Directions of different possibilities within each level also varied among farmers. By identifying those four levels, a model for understanding the farmers' choices is provided. This provides background for dialogue with each farmer about choices in the context of each specific herd. It also provides insight into implications of mastitis treatments for effective treatment versus issues of antibiotic resistance when discussing choices on a more general level. Communication and understanding between farmers and their veterinarians and cattle-oriented advisors is essential. Farmers were shown to be coherent in their choices of treatment, but their decisions often seemed to differ from normal veterinary recommendations. Such differences have to be understood and implemented into effective decisions for the whole farm.

For several decades after the first description of bovine viral diarrhea and its causative agent (BVDV) the economic impact of the infection was underestimated and in addition there were no suitable diagnostics and procedures for a systematic control at hand. Today, there are several estimates on the real economic impact of the infection and during the last 15 years the serological and virological laboratory diagnosis of BVDV infections has improved. Also, successful procedures aimed at eradicating BVDV infections by using a strict test and removal policy for animals persistently infected (PI) with BVDV accompanied by movement restrictions for infected herds have been implemented in the Scandinavian countries. The success of these efforts has encouraged other European countries to follow the same procedures. However, the Scandinavian control strategy might—for a number of reasons—not be acceptable for all European countries. In such cases, the test and removal strategy, with its fundamental elements of biosecurity, removal of PI animals and monitoring of herd status, in combination with systematic vaccination, might be an acceptable compromise. The impact of the BVDV-free status of regions and nations on international trade is not yet clear. In any case, biosecurity measures will be of utmost importance for individual control programs as well as multiple control programs to co-exist in Europe.