Animals in research The statistics In 2015, the number of animals used for the first time in procedures for scientific purposes was 4.07 million (4,069,349). The number of procedures that were conducted on animals is slightly higher at 4.14 million (4,142,631). These numbers, over the past few years have remained fairly similar with both the number of animals used and the number of procedures conducted hovering around the 4 million mark consistently. As in previous years, the number of animal procedures that took place for the breeding of genetically modified (GM) or harmful genetic mutation (HM) animals remained at approximately 50% of all procedures conducted (2.06 million procedures). GM animals are defined as those with genetic characteristics that have been altered using genetic engineering and HM animals are those possessing one or more genes that have undergone mutation either naturally or deliberately induced and that are known to be harmful to the animal. The main reason for such large numbers is the creation of many different animal strains with very specific and targeted genetic mutations to single genes. Such specifically altered animals (mainly mice) would require a large number of additional identical animals to be bred in order to maintain the desired mutation within that particular strain. Over the last 10 years, the total number of procedures has increased by 37% (an increase of 1.11 million procedures). The creation/breeding of genetically altered animals has primarily accounted for this rise (1.00 million procedures) whilst the increase in the number of experimental procedures is much smaller (107 thousand procedures). Of the 2.08 million experimental procedures completed in 2015, the majority involved mice (61% or 1.26 million procedures), fish (14% or 294 thousand procedures), rats (12% or 258 thousand procedures) and birds (7% or 141 thousand procedures). Experimental procedures involving specially protected species (i.e. horses, donkeys, dogs, cats, and non-human primates) accounted for 0.8% (17 thousand) of procedures in 2015. For the full report on the statistics on animal use in scientific research visit the National Statistics page for Annual statistics relating to scientific procedures performed on living animals in accordance with Animals (Scientific Procedures) Act 1986 on the GOV.UK website. Animal Free Research UK is showing how research that helps us fundamentally understand human biology and disease can and should take place without the need to use any animals.