Great Britain releases 2018 statistics on animals used in research

The UK annual statistics of animals used in research have been released, showing the number of procedures on animals has decreased by 7% to 3.52 million.


The UK does not allow the testing of cosmetics or cosmetics ingredients, tobacco research or the use of Great Apes. This research must be undertaken in other countries if it is to occur.

Image of mice courtesy of Understanding Animal Research

The UK counts both procedures undertaken and the number of animals used for the first time. Since studies may last over several years and more than one procedure can be undertaken on an animal, neither measure tells us exactly how many animals are used in a year. Hence, procedures are commonly used as a guideline since these are likely to be an overestimate which cannot downplay the number of animals used.

Mice, fish, rats, and birds account for over 97% of all UK procedures.

Primates and dogs are used much more sparingly at around 0.2% of experiments, or 7,688 animals. Most dogs and primates are used in regulatory toxicology, such as repeat-dose toxicity studies, which is where a dose of a candidate drug is given every day, perhaps as a pill hidden in food, for a two-week period. The animal’s health is carefully monitored during this time for ill-effects, and the animal will usually be humanely killed at the end of the experiment so that tissues and internal organs can be studied for the same.

However, this is not representative of the majority of research, which is most often basic research into how biology works and breeding genetically altered animals to study things like gene function.

Around 500 primates may be used for more invasive procedures, which are typically mild or moderate in nature.

We know this because the UK records the suffering encountered in experiments, categorising procedures as mild (equivalent to a blood draw), moderate (implying surgery under anaesthetic followed by recovery), severe (either severe physical or psychological suffering or prolonged moderate suffering), non-recovery (death whilst under general anaesthetic) or sub-category (milder than mild).

This is a picture likely replicated across international research, with ‘shocking’ high headline numbers actually referring to high-throughput but mild experiments with a much smaller number of animals used in carefully-conducted invasive procedures.

Also international in nature is the bulk of experiments being publicly rather than privately funded. This is due to the fact that the returns on investment of animal research do not always take a short-term financial form, but may bring more subtle benefits such as economic benefits not enjoyed directly by the investor, social benefits or environmental benefits.

If a person is able to work due to disease being treated or prevented, for instance, they create wealth, and whether that is taxed or left in their hands is irrelevant – the benefit is clear. Vaccines, for instance, are thought to generate between $2 and $27 for every $1 spent on them.

Basic research of the sort commonly funded by public bodies can also take a while to pay off financially. As an example, the work of Sir John Gurdon on frogs in the early 1960s, which won the Nobel Prize for Physiology in 2012, has paved the way for medicine personalised for the individual.

The benefits of this will be manifold, from better personal health for the individual, to the benefits to society of healthier individuals, to the reduction of burdens on businesses and the state generated by people in suboptimal health, to the speculative opportunities presented by providing services like genetic screening. However, would those benefits have been quantifiable or attractive to a private investor looking for a return in 1962? I’d venture not.

In common with previous years, commercial organisations make up around 23% of experimenters, suggesting this is the natural level of ‘for-profit’ research in the UK, whereas around 50% is undertaken by universities, 17% by not-for-profits like charities and around 10% government departments, public bodies and public health laboratories.

Although today’s statistics show an increase in the number of dogs and primates used, this masks a long-term trend downwards. In the past ten years, for instance, there has been a 24% reduction in dogs, a 25% reduction in primates and a 42% reduction in the number of cats used. Over this same time period, however, there has been a 19% increase in the number of horses used, demonstrating that, although some uses of animals diminish, other species can rebound as science takes things in a new direction.


An explosion in the use of genetically altered mice since the year 2000 is a case in point, with numbers increasing to some 40% of all experiments in 2019. Indeed, this explosion masked a decline in other types of experiment which have been on a downward trend since the mid-1970s.


Year-to-year numbers are thus best seen as a reflection of the current health of UK bioscience investment and will fluctuate year-on-year, which is great if you’re a journalist wishing to get either a ‘shocking’ or ‘uplifting’ story about a greater or fewer number of animals used but, if someone wishes to understand the direction of travel, it is a slow reduction of animals used over time, with the large number of animals recorded attributable largely to the fact the UK includes all vertebrates used. Low-suffering, high throughput experiments are also bundled in with brain surgery and rarely severe procedures, with what counts as a procedure including experiences that are milder than mild.

There may be 3.5 million experiments, but most of these will involve mild experiments using a mouse – very few of them will involve brain surgery on a monkey.

Chris Magee


More information on UK regulations governing lab animal use can be found here:

The Home office report on its statistics can be found here:

The tables of how many animals of what species are used for what purpose are here (opens as an ODS in Excel or Open Office):