What activity would disqualify an animal from USDA category B?

USDA category B refers to animals that are bred for research but have not yet been used in any procedure that would subject them to pain, distress, or harm. Blood collection is a direct procedure that could potentially cause pain or distress to the animal. Therefore, any involvement of an animal in such a procedure would indeed disqualify it from being classified as a USDA category B animal.

In contrast, other activities such as being placed into new caging, breeding, or being observed during quarantine do not involve procedures that would inflict pain, distress, or harm in the same way blood collection does. For instance, moving to new caging or observing during quarantine typically involve less invasive interactions, and breeding may not inherently cause distress, depending on how it is managed. Thus, only blood collection stands out as an action that contravenes the criteria for USDA category B classification.