Mastitis in cows can be a very complex illness since the farmer may not be able to detect it during its subclinical phases. This is to say that the herd may have mastitis without showing any signs and symptoms. At this stage, the disease can spread very fast to the rest of the herd if proper handling is lacking in the farm.
Many of the infectious diseases found on dairy farms have a negative impact on production and profitability. Animals may become clinically ill and need veterinary care, and some may die, but many infected animals do not show noticeable clinical signs. These animals might have reduced milk yield or weight loss and often have the most significant impact on profitability. Being able to properly identify and monitor diseases of dairy cattle is an important step in preventing side effects from these situations. Most diseases can be easily tested for and, once the cause is identified, a plan can be made for control, eradication, or prevention.