UK researchers performed a greater number of experiments involving animals in 2012 compared to the year before, with hundreds of thousands of additional experiments taking the total number of animal procedures to 4.11 million.

Data released today by the UK Home Office show an overall 8% rise — or 317,200 more procedures — that was mainly down to an uptick in breeding of genetically modified (GM) animals and mutant strains of mice.

Since 1986 the United Kingdom has collected data on animal ‘procedures’ rather than actual number of animals used. Breeding a GM animal and then conducting two experiments could therefore be counted three times in these statistics. The Home Office report says the number of procedures “generally corresponds” to the number of animals.

After dropping off from record-high numbers in the 1970s, animal research numbers in the country started increasing again around 2000 (see graph). They have continued to rise year on year since then — a growth generally put down to the increasing utility of GM animals in biology. In 1995 only 12% of procedures were breeding of GM or other ‘harmful mutant’ (HM) animals. In 2012 that number was up to 48%.

In total in 2012, 4.03 million animals were used in procedures for the first time. Mice accounted for 76% of this total.

There was also an increase in the use of primates. However, the group Understanding Animal Research  — which campaigns in support of animal research — says: “this is partly due to a large drop in primate procedures in 2011 and the figure remains 36% lower than in 2010”.