What principle focuses on ensuring that a system remains active once it has been established?

The principle that focuses on ensuring that a system remains active once it has been established is active maintenance. This concept emphasizes the importance of regular monitoring, updating, and adjusting systems to ensure their continued functionality and relevance. Active maintenance involves implementing proactive measures to keep the system operational, address potential issues before they escalate, and adapt to any changes in the environment or requirements.

In a veterinary pharmacology context, this could relate to the ongoing need to review and optimize drug protocols, maintain accurate records, or ensure that inventory levels of medications are sufficient to meet patient needs while adhering to regulations and best practices. Active maintenance ensures that systems, whether they pertain to pharmaceutical stock management or client follow-up protocols, do not become stagnant, which is crucial for the effectiveness of veterinary care.

The other options describe important concepts related to system oversight and improvement. Regular reviews are essential for evaluating the system's performance over time. Ongoing management highlights the continuous effort needed for effective governance of a system, while continual engagement involves actively involving stakeholders to ensure their needs are met. However, it is active maintenance that specifically emphasizes the operations required to keep a system in an active state after it has been put in place.