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In 2015, researchers estimated that approximately 192.1 million animals were used for science annually worldwide. This calculation was complicated by the fact that many countries — especially across Africa and Latin America — do not collect and publish this information.

In 2001, the Mexican government passed legislation to standardize the use of laboratory animals at institutions, specifically mice, rats, guinea pigs, hamsters, gerbils, rabbits, dogs, cats, pigs, and primates. According to the legislation, laboratories are meant to provide an annual report with the number of animals used and for what purpose.

The National Service for Agro-Food Health, Safety, and Quality (SENASICA) is responsible for collecting this data. They also authorize laboratory facilities and are supposed to promote laboratory animal welfare. Lab animals are meant to be protected by federal, state, and institutional laws, and as a member of the World Organisation for Animal Health, Mexico is obliged to follow the Terrestrial Animal Health Code. 

Unfortunately, each laboratory operates under its own set of internal regulations, so the data is not uniform. It’s also not publicly available. This lack of transparency in animal-use statistics prevents a clear assessment of current regulations that would help with informed decision-making. 

To try to remedy a lack of coherent and cohesive data, this study attempted to calculate the number of animals used for science in Mexico in a systematic way. A total of 423 reports were requested from national and state institutions. Given that the most recent estimation was done in 2015, the authors measured the period from 2015 to 2021.

From these reports, 80 institutions declared the use of animals in the name of science. Facilities included research centers, schools, hospitals, national institutes, colleges, and universities. Uses involved research innovation, development, diagnostics, testing, quality control, and education.

According to SENASICA data, 5,437,263 animals were used over the six-year period. However, this number is just a fraction of the total, because only 10 of the 80 institutions were authorized by SENASICA. In other words, SENASICA does not have the data from 88% of the institutions that use animals. Moreover, of the other 70 institutions, many did not know or keep proper records of their animal-use statistics.

Even using this low fraction, the results showed that more animals are used for science in Mexico than was previously estimated. The 2015 research team used data from published studies to estimate that Mexico uses 277,689 animals for science each year. In contrast, the results from this study estimate that 484,235 animals were used in 2015. This discrepancy suggests that many animals are used for education, and/or research that is never published.

The number of animals used increased over time, which is consistent with trends in other countries. In other words, more animals are being used for science in Mexico now than ever before. In terms of species, mammals — especially mice and rats — are used most across the animal kingdom. Fish were the second highest group reported, likely due to the growing aquaculture sector in Mexico.

This study also found that the scientific use of many species is not currently covered under animal protection laws in Mexico. This includes wildlife (such as birds) and invertebrates, who are commonly used in labs around the world, but whose use is not often regulated, or even counted. 

The authors recommend implementing a national surveillance system to hold all institutions accountable for standardized, annual reporting. Metrics should include the numbers of each species used, the purposes of use, and the severity of the procedures. The data would be continually updated in a publicly accessible database to monitor compliance, evaluate progress on animal welfare, and assess implementation of the Three Rs principle (reduce, refine, and replace animal data). Finally, legislation should be extended to cover all species used for science.

In addition to supporting these recommendations, animal advocates can highlight the benefits of alternatives to animal research for scientific progress. Aside from the ethical problems of gathering animal data, animal-free methods model human disease more reliably and translate into treatments more predictably.