Antibiotic use in animals

Antibiotics are often used in food animal production. Consumption in the food animal sector was estimated at 99,500 tons in 2020, with sales predicted to increase by 8% by 2030. For aquaculture, the estimated global consumption is around 10,000 tons. Similar to the situation in humans, antibiotic consumption can increase carriage or infections with resistant bacteria in the animal population.

Used in healthy animals, and with large variations between countries

In most cases, antibiotics are administered to healthy animals for growth promotion or prevention of disease rather than to treat disease. There are great variations in antibiotic use in animals between countries, which cannot be explained only by differences in animal species and production systems. Antibiotics are sometimes used to compensate for poor farming practices and are expected to improve production. However, it is possible to combine high productivity with low use of antibiotics, as has been shown for example in the Nordic countries and New Zealand.

Impacts animal, human and environmental health

Resistant bacteria are frequently found in surveillance programs within the farm animal sector. Not only does this risk the health of the animals and in turn productivity. These bacteria may also spread to humans, by direct contact and indirectly, for example via the food chain or contaminated water. This is well known to occur with MRSA in swine farmers. Also, similar resistance genes have sometimes been detected in food animal samples and patients within the same geographical areas. A recent example is the mcr-1 gene that gives resistance to the last-line antibiotic colistin. Bacteria with mcr-1 were first discovered in China, but have now been found worldwide in the environment, animals and humans – even causing disease in patients. Higher abundance of the mcr-1 gene in isolates from food animals compared to human isolates, the much higher use of colistin in animal farming compared to human medicine, and the finding of mcr-1 together with genetic elements typically seen in animal environments, indicates a flow from animals to humans.

Today, we don´t know the magnitude and importance of transmission from animals to humans for the increasing resistance rates observed in human pathogens. Increased awareness among professionals and consumers, surveillance systems for animal antibiotic use and resistance, improved practices to prevent disease (such as vaccination and improved animal husbandry) and availability of diagnostic tools are cornerstones in the future work to promote rational antibiotic use in animals. Regulations on antibiotic use, such as a ban of antibiotic growth promoters and restrictions on routine mass medication, are powerful tools that are being discussed and already implemented in many countries.

© Uppsala University