Congratulations to the USDA/APHIS for getting ahead of the curve for a second time and making the US the first country to publish its 2015 animal research statistics. Overall, the number of animals (covered by the Animal Welfare Act) used in research fell 8% from 834,453 (2014) to 767,622 (2015).

These statistics do not include all animals as most mice, rats, and fish are not covered by the Animal Welfare Act – though they are still covered by other regulations that protect animal welfare. We also have not included the 136,525 animals which were kept in research facilities in 2015 but were not involved in any research studies.

The statistics show that 53% of research is on guinea pigs, hamsters and rabbits, while 11% is on dogs or cats and 8% on non-human primates. In the UK, where mice, rats, fish and birds are counted in the annual statistics, over 97% of research is on rodents, birds and fish. Across the EU, which measures animal use slightly differently, 93% of research is on species not counted under the Animal Welfare Act (AWA). If similar proportions were applied the US, the total number of vertebrates used in research in the US would be between 11 and 25 million, however there are no statistics to confirm this.

If we look at the changes between the 2014 and 2015 statistics we can see a drop in the number of studies in hamsters, rabbits, cats and the “all other animals” category. Notably, there was a 7.3% rise in the number of non-human primates used although this comes the year after a 9.9% fall in their numbers.

There has been a downward trend in the number of AWA-covered animals used in the last three decades, with a 64% drop in numbers between 1985 and 2015. It is also likely that, similar to the UK, a move towards using more genetically altered mice and fish has reduced the numbers of other AWA-covered species of animals used. In the UK this change in the species of animals studied has contributed to an overall increase in the numbers of animals used in research in the past 15 years.

Rises and falls in the number of animals used reflects many factors including the level of biomedical activity in a country, trending areas of research, changes to legislations at home and abroad, outsourcing research to and from other countries, and new technologies (which may either replace animal studies or create reasons for new animal experiments).

It is important to note that the number of animals cannot be tallied across years to get an accurate measure of total number of animals. This is because animals in longitudinal studies are counted each year. Thus, if the same 10 animals are in a research facility for 10 years, they would appear in the stats of each year – adding these numbers would incorrectly create the illusion of 100 animals being used.

Speaking of Research welcomes the open publication of these animal research statistics as offering the public a clear idea of what animal research goes on in their country.