Cow-Side test: What is useful and cost-effective in cattle practice?

On-farm ancillary exams have been considered as needless in cattle practice. For a long time most of these exams could only be performed by laboratories. Only few analyses could be done on the field, but with inaccurate, slow or expensive results. Nowadays, new devices appeared on the market, with greater accuracy for lower prices. The goal of these tests is not only to provide a better diagnosis, but also to improve communication with the owner, and also to give a quick therapeutic answer or a prognosis.
The ancillary exams have to be profitable for both the owner and the practitioner. It can be done at an individual or herd level to demonstrate the subclinical diseases. The benefits of field-tests are essentially saving time, and for some assays, saving money as well, with relatively accurate analyses. In order to adapt to the situation, it is advised to know the sensitivity and specificity of the tests before doing the analysis. In some cases it is necessary to have a better sensitivity or specificity to adapt to goals: avoiding false-positive or false-negative results. A good specificity of a test is required while looking for a diagnosis, as for a screening approach, a good sensitivity is preferred.
Anyway, the use of field tests must be thought carefully and realised only after complete clinical examination of the patient. As it is previously mentioned, the ancillary exams are an important communication tool with the client, and a starting point to a dialogue to convince him to the implementation of appropriate corrective measures in the herd.
Here are only presented the different field tests that can be done within 15 minutes, beside the animals, in the barn. Tests are explained in the well-known order (as a disease will act): inflammatory, metabolic, immunological response and the potential presence of the infectious agent.