Merck Manual

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Professional Version

Biosecurity of Animals


Montserrat Torremorell

, DVM, PhD, Department of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota

Reviewed/Revised Feb 2021 | Modified Nov 2022

The tenets of biosecurity have been long recognized by veterinarians. However, throughout the past decades, interest in biosecurity as a scientific discipline has surged because of 1) disease outbreaks that have threatened to devastate agricultural economies, and 2) bioterrorism. In fact, the meaning of the term biosecurity and the structure and focus of biosecurity programs have evolved throughout time to more accurately reflect the scientific community’s evolving perception of disease as well as the needs of the consumer, the veterinary profession, and producers and owners.

In modern animal medicine, biosecurity is probably best defined as “all procedures implemented to reduce the risk and consequence of infection with a disease-causing agent.” This broad definition recognizes that disease is a complex interaction between the host, the disease-causing agent, and the environment. Biosecurity can be considered in terms of individual animals or populations of animals (flocks or herds), economic entities (production facilities or companies), or geographic regions (counties, states, countries, or continents), thus facilitating compartmentalization for trade purposes. Importantly, it addresses strategies for both disease prevention (eradication) and control (limiting the consequence of infection).

Benefits of an effective biosecurity program include optimized animal health and welfare and, in the case of food animal medicine, improved productivity and end-product value, reduced economic losses, and safe regional/international trade. Although implementation of a comprehensive biosecurity plan or program has obvious benefits, allocation of resources must be economically (food animals) or emotionally (companion animals) justified. Unless a disease poses a specific risk to human health or animal welfare or to substantial economic losses, its mere presence in an individual animal or population of animals is not significant. Intervention strategies are consequently chosen based on both their economic and biologic efficiency.

A dynamic and integrated epidemiologic and economic analysis is required to determine and quantify the negative effect of a disease challenge, and the anticipated positive response to the proposed intervention strategy. Such integrated analysis has become significantly more important in intensive production systems.

The economic impact of disease can be difficult to assess. This is particularly so in intensive production systems in which economic return is governed by not only animal productivity but also product quality. In addition, the consequential loss from disease challenge is, at best, only partially recoverable. Using the cost of disease to justify intervention overemphasizes the consequence of inaction, and it is useful only in justifying intervention strategies directed at preventing disease challenge.

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