Monitoring Antimicrobial Drug Usage in Animals: Methods and Applications

Monitoring antimicrobial drug usage in animals at the national and international levels is important for identification and tracking if and how often quantities are used. This information can be used for many purposes, including raising awareness, comparing use patterns across countries, identifying trends over time, integrating with antimicrobial resistance data, conducting risk assessment, and evaluating the effectiveness of measures to manage antimicrobial usage. The goal of this article is to describe how monitoring systems for antimicrobial drug usage in animals are set up and conducted, using examples from specific countries as well as international efforts. Several key figures and variables are used to describe and evaluate antimicrobial consumption in animals, including the amount in kilograms of active ingredient, standardized units (e.g., number of defined daily dose animals, DDDAs) and number of treatments (e.g., number of used daily doses, UDDA). Data can be collected from a variety of sources including pharmaceutical sales, pharmacy dispensing, veterinary prescriptions, and farm records. In many countries, data analysis and reporting at the national level provide statistics on overall quantities used in animals, in some cases by animal species. Antimicrobial consumption data should be contrasted to the respective animal population, for example, the weight of different categories of livestock and slaughtered animals. Several countries have established antimicrobial usage monitoring systems. Most report overall sales data, but some provide usage data to the levels of animal species and production type. At the international level, several organizations (e.g., European Union, World Organization for Animal Health, World Health Organization) have initiatives to support the development of antimicrobial consumption data collection and reporting. However, these initiatives are ongoing and so far lack harmonization, which will be the biggest challenge for the future.