Handling sick animals before healthy ones significantly increases the risk of disease transmission among livestock. When an individual interacts with or tends to sick animals first, pathogens present on those animals—such as viruses, bacteria, or parasites—can easily be transferred to the caregiver's hands, clothing, or equipment. This contamination poses a serious risk when the same person subsequently handles healthy animals, as they may unwittingly introduce the pathogens into the healthy population, leading to outbreaks of disease.
In contrast, feeding animals before examination does not inherently contribute to disease transmission; it is the management practices around handling sick individuals that are more critical. Isolating new animals from the rest of the herd is a preventative measure meant to reduce the risk of introducing diseases and is a recommended practice to safeguard the health of the entire group. Keeping equipment sanitized is another essential biosecurity measure that helps to minimize the spread of infectious agents. Both of these practices would serve to protect animal health rather than pose a risk.
Hence, handling sick animals first fundamentally disrupts effective biosecurity protocols and is a significant factor in disease spread among livestock.