Animal tests


The majority of products that you use in your bathroom, your kitchen, garden or for your car, including food products, have been tested on animals at some point to see how much of that product is poisonous (toxic) and what effects it has on the body. These cruel animal tests  can be replaced with advanced technology and also, with predications based on the vast knowledge we already have about the effects of chemicals, from human use.  However, despite the alternatives available, animal tests continue because that is the way that things have always been done.

NAVSweb_HLS arrivalPrimates and dogs are used in regulatory tests (toxicology, safety tests), which are required for a licence for a product to be sold on the market. Regulatory testing represents over 50% of the 6,000 primates used in European laboratories each year. Each year in the UK around 3,000 dogs and 2,000 monkeys are subjected to painful experiments to test the safety of different chemicals and drugs for human use.

Animal tests have always been used because animals are available, and the animal testing technology is over 100 years old. However, there are no specific legal requirements for the use of primates or dogs in regulatory testing – the regulations specify that two species of mammals are to be used and one must be a non-rodent species.  So the idea is that the tests are started with smaller animals such as rats and mice, and then move on to larger mammals like dogs and monkeys. In theory, dogs and monkeys are used at the end of the testing strategy. However, an analysis of animal toxicity data of over 3,000 drugs concluded that further data from the second species does not solve the problem of extrapolating results to humans.

For example, safety/toxicity testing of a drug is about a key piece of information – the way a drug travels through the body – the rate and route by which it breaks down, before being excreted. This is crucial and affects how the drug affects the body. However, our genes and other factors influence this process. These key genetic differences between humans and other animals are hugely important in drug development and testing – despite the similarities between humans and the other primates such as use of tools, language, emotions and intelligence.

Case Study:  Huntingdon Life Sciences (now called Envigo) Laboratories

Huntingdon Life Sciences is a major European contract testing laboratory; they perform the standard animal tests required by regulators on behalf of their clients, the manufacturer of the product being tested – drugs, chemicals, and other products (for example things used in the home).

A case study by the National Anti-Vivisection Society (NAVS) provides an insight into the functioning of a typical European commercial testing laboratory, Huntingdon Life Sciences (HLS). The nature of the experiments conducted  on behalf of their clients (including GlaxoSmithKline, the Ministry of Defence and AstraZeneca) was to look for adverse effects or symptoms of test compounds.

During the investigation, the numbers of monkeys (cynomolgus macaques) observed being used in tests ranged between 4-72; just five studies accounted for the lives of 217 animals. Monkeys arrived from breeding colonies in Vietnam and tests typically involved restraint, being captured from their cages and firmly grasped by their arms, legs and tail. Three monkeys suffered rectal prolapses during one study. Rectal prolapse is known to indicate extreme stress in monkeys and tells us that they suffered terribly – probably as much through fear and anxiety as anything else.

NAVSweb_HLS restraintAn incontinence drug was given daily for a year, by forcing it down monkeys’ throats with a pipe (gavage dosing). The monkeys were removed from their cages, restrained and had the tube pushed down the throat to deliver the product being tested. Some of the monkeys vomited every time they were dosed, including ‘control’ monkeys who did not receive the drug, indicating that the procedure itself, not the test substance, was causing vomiting. Gavage is known to be unpleasant for animals; monkeys are observed to “forcefully resist such intervention”.  During this study, several animals suffered prolapses, which appear to be the result of fear due to anticipation of the procedures.

Yet a review of the incontinence drug market found at least 13 other incontinence drugs in development in the US, Europe and Japan. The market for these drugs was set to become “extremely competitive”.

Tests for a blood clotting drug involved 56 monkeys: they were put in restraint chairs and the substance administered through a cannula inserted into the back of their leg over a period of 2-15 minutes. Animals were bled before and during the study and were fasted every night before they were dosed.  Some animals were killed 24 hours after dosing and others were killed two weeks after dosing.

One female was trembling during dosing, indicating distress. It is known that biochemical changes in the body as a result of stress can influence the outcome of a test “which can cause anomalous experimental results”. Almost a decade before these tests on monkeys, a review of animal models of a blood clotting disorder led to the conclusion that differences in the animal and human disorder cannot be avoided, so “…one should be cautious about extrapolating the results from animals to humans” .

Case Study: Inveresk Laboratories

Documents and photographs, including reports of commissioned experiments were leaked to the NAVS. They provide a chilling insight into the world of ‘contract research’ – commercial safety testing. The company stated they would help businesses to comply with the EU’s REACH chemicals regulations by carrying out animal experiments on their behalf.

NAVSweb-InvereskAn asthma drug tested on monkeys involved a cannula being inserted into the leg vein of 16 animals where it remained so that they could be dosed daily for 14 days. The animals were then killed. Monkeys were observed for any signs of ill health or reaction to treatment. In order to obtain samples for analysis, the monkeys were deprived of food and water.

From approximately 5 minutes after dosing, all of the animals suffered reddening of the face and lips; this increased with dose levels, in terms of both incidence and length of time. They also experienced a range of symptoms including diarrhoea, swelling in the stomach, redness of feet and hands, white pigmentation on the feet; the males’ testes increased in weight and they suffered red and swollen penises and scrota. In addition, the monkeys were reported to be subdued and hunched on their branches; body tremors were seen in one; another did not use its right leg throughout the test, apparently due to “an injury”; and females suffered abdominal and umbilical hernias.

The report of one study admits that the client, AstraZeneca, was in possession of information from previous experiments on these monkeys, which indicated “the test compound may affect the cardiac function and produce pericardial effusion in cynomolgus monkeys when given intravenously or via inhalation”. The use of cynomolgus monkeys has also been criticised as being the most misleading laboratory animal model for the study of human cardiotoxicity (i.e. toxic effects on the heart), yet this is one of the key questions that the test intended to address.

The experimental drug was intended for inhalation administration in people, but the drug was given to the monkeys directly into the bloodstream. Yet it is already known that side effects can differ, dependant upon whether a drug is given through the blood stream, or inhaled. Results obtained on the effects of a drug administered through the vein may be misleading if the drug is intended for inhalation.

Case study: BIA 10-2474 and human tragedy

In January 2016, six volunteers were hospitalised following adverse reactions to a drug that was being tested by French research company, Biotrial, for Portuguese pharmaceutical company Bial. The drug, BIA 10-2474, was being tested as a pain killer among other possible uses for the first time in humans.

Within three days of taking the drug, a volunteer in a high dose group was admitted to hospital after beginning to feel sick. The remaining volunteers in the same group continued to receive the drug, until the hospitalised volunteer’s condition deteriorated and he was diagnosed as brain dead the following day. A week later he died. The other five men were hospitalised, with MRI showing evidence of deep bleeding and tissue death in the brain.

The symptoms experienced by these volunteers in the highest dose group included: headache, problems with their movement and walking, uncontrolled eye movements, slurred speech, dizziness, fatigue, diarrhoea, brain lesions and bleeding on the brain. It has been reported that at least one of the volunteers lost all his fingers and toes. One volunteer also showed signs of amnesia, struggling to remember events two months before taking the drug and one month after.

Ten volunteers in a lower dose group also experienced problems such as dizziness and blurred vision. Almost a year later, four of the volunteers who became ill had not yet fully recovered from their neurological symptoms and continued to suffer memory loss, headaches, motor disorders and tremors.

Animal test results failed to predict dangers


Prior to studies in human volunteers, the drug had been tested extensively on mice, rats, dogs, and monkeys for toxic effects on the heart, kidneys and gastrointestinal tract, and on rabbits and rats (including their foetuses) to determine its reproductive and developmental toxicity effects. It has been estimated that monkeys were given doses of the drug approximately 75 times greater than the highest dose given to patients, with no ill effects. Animals in the preclinical studies would have inevitably suffered during dosing for these tests, as well as from any side effects of the drug.

Toxicity testing was carried out daily for up to 13 weeks in mice, dogs and monkeys, and up to 26 weeks in rats. Oral dosing for toxicity testing often involves animals being restrained while tubes are pushed down their throat so that drugs can be delivered directly into the stomach. Most procedures carried out on primates require restraint. NAVS investigations have shown the capture of monkeys from their cages involving a technician grabbing the monkeys from their cage. Three workers are usually needed; two to hold the animal, one to perform the procedure. The monkey’s arms, legs and tail may be held with the animal face up or face down. All terrifying, and extremely stressful, for the monkey.

Despite the fact that all of these animal tests did not predict the tragic outcome in humans, researchers have carried out more animal tests in an attempt to determine the causes of the adverse events. Tests on rats involved injecting the compound into their tails before killing them by cutting off their heads, so that their brain could be removed for analysis. Astonishingly, researchers admit that extrapolation of their results “from rodents to human is fraught with error”.

The reason for the toxic effects of the drug remains unknown, with scientists stating that “precisely how a drug that seemed to be safe in animal testing and other early testing in people turned out to be deadly is still unclear”. A report from an investigative committee concluded that “no toxicity, especially neurological (central or peripheral) comparable to that observed in the accident in Rennes, appears to have been demonstrated in animals, despite the use of 4 different species and high doses administered over long periods”. It is clear that animal testing did not make the human trials safe.

Other failed drug trials


Anti-inflammatory drug TGN1412 was given to healthy volunteers in doses 500 times weaker than that given to lab monkeys, but in an hour the volunteers were so seriously ill that they had to be transferred to intensive care. They suffered multiple organ failure caused by a massive immune reaction. One volunteer spent 147 days in hospital with heart, liver and kidney failure and had all his toes amputated and the tips of several fingers removed.


The anti-inflammatory drug Vioxx had unexpected effects on human patients, after laboratory animal tests. It has been reported that from 88-140,000 extra heart attacks may have been caused by Vioxx in the five years since its introduction with between 38,720 and 61,600 deaths. It was found to increase the risk of heart attack by 34% compared to people on similar drugs. Many of the participants in the trials were at lower risk of cardiovascular disease than the elderly population that would use Vioxx, so the risk to the intended recipients may have been even greater – up to eight times greater.


The heart drug, Eraldin was thoroughly studied in animals and satisfied the regulatory authorities. None of the animal tests warned of the serious side effects in people, such as blindness, growths, stomach troubles, and joint pains.


Opren, the anti-arthritis drug, was passed safe in animal tests. It was withdrawn after causing more than 70 deaths, and serious side effects in 3,500 other people, including damage to the skin, eyes, circulation, liver and kidneys.

Replacing animals – the alternatives

The alternatives to the use of animals in safety testing include databases of known information, human tissue culture and sophisticated analytical techniques. Many non-animal techniques are already used before animals are used, but regulations still require animal tests. See more here

Fundamental and applied research

Outlined here are examples of academic research with no direct application to human health as well as applied research which is carried out with a disease or human ailment in mind; however, researchers often fail to address species differences in attempting to apply results from animal models to humans.

Case study: Brain research on monkeys – decades of suffering with no human application

The kind of experiments on monkeys’ brains that we describe here, fall into the category of fundamental or academic research, animal experiments to gather information or data, but with no intended application for human health. Such projects can continue for decades, with no end in sight. For example:

At the Institute of Neurology in London a series of experiments has been funded by The Wellcome Trust, the National Centre for the 3Rs (Refinement, Reduction & Replacement of Animals in Research), and the Biotechnology & Biological Sciences Research Council.

A 2011 report describes an experiment where the heads of three macaque monkeys, two male and one female, were cut open to fix a head piece to restrain their heads and implant a recording chamber and electrodes into their brains. Electrical current was delivered to the brain. The monkeys had to grasp different objects for food reward while their brain activity was recorded both with and without electricity being applied to the brain. Two of the animals were killed at the end of the experiment.

The team received funding for this research, despite that they themselves cite a number of similar experiments on primates, and similar work using humans. The researchers don’t specify how this research might be helpful for humans and there is no discussion in the published paper, of the known differences between human and monkey brains.

NAVSweb_ElisaOne of the authors of this paper, Roger Lemon, has been carrying out invasive brain experiments in monkeys for decades. An investigation and case study by the NAVS in 1996 documented that, at that time, Lemon had already been working on experiments involving primates using chronic recording and stimulation techniques for twenty years.

The same group of workers published a similar paper in 2013, where two monkeys also received repeated surgeries and implants in the brains and this time into their arms, again to monitor brain activity.

There are fundamental differences between human and monkey brains. A study comparing the processing of motion in the human and macaque brains commented that “a complete homology between cortical areas of humans and monkeys is highly unlikely” considering anatomical and behavioural differences and the 30 million year evolutionary gap between the two species.  It also highlights how the specific areas of the brain involved in these cruel experiments differs between humans and monkeys.

There is no doubt that these monkeys will have suffered extreme fear and distress, as well as the pain of surgery, and yet Roger Lemon and his team acknowledge that non-invasive studies using human subjects are already carried out.

Case study: French dental study on monkeys

At the National Veterinary School of Lyon, France, researchers simulated human periodontal disease in 8 healthy long-tailed macaque monkeys, in a study funded by Dental manufacturing company, Dentsply.

A 2014 report describes how researchers performed multiple surgeries on the roots of monkeys’ teeth to study the effect of dental cavity material on healing. Monkeys’ gums were cut to expose roots of the teeth and jaw bones. A 3mm cavity was drilled into the tooth base and the outer layers were removed with a hand scaler. Inflammation was induced in the gums. During a second surgery various substances, including one derived from brains, were used to fill in the damaged teeth.  A total of 8 cavities were created in each monkey. The monkeys underwent numerous CT scans until they were killed 12 weeks later by anaesthetic overdose and draining of the blood, and their jaws cut in to pieces for further analysis.

There is no question that these monkeys would have suffered extreme fear and pain during this study.  As well as the direct impact of the invasive dental treatments, the monkeys would have suffered from the associated effects of recovering from the numerous surgeries and scans. At one point the monkeys were only fed soft food, so that food would not interfere with the surgical sites; this gives an indication of how delicate these sites were – and no indication is given as to whether pain killers were administered.

The research was carried out despite a number of previous studies which investigated the healing effects of the same dental materials, including studies in dogs. In addition, studies in humans have already been carried and treatments for halting the progression of periodontal disease in humans are already successful.

The authors also note that “the induced inflammation referred to in the current study is different from the inflammation caused by periodontal diseases”.  Human studies of regeneration in periodontal disease have highlighted that researchers need to take into account the effect of systemic factors in patients, such as metabolic disorder, and risk factors such as smoking, medication and genetic susceptibility.  Such consideration cannot be made in an animal model that has been artificially created in the laboratory.

Overall, this study does not add any new information apart from testing in another non-human species; it reports the same findings and just adds to this existing data.

Case study: Spinal experiments at University of Newcastle

At the University of Newcastle, two female macaques suffered restriction of food to motivate them to perform motivation to perform in experiments where they were trained to grasp and pull a handle for a food reward. Monkeys underwent three surgeries implanting various devices into their hand muscles, brain and spine. They had recording chambers fixed to their heads, which allowed electrodes to be inserted into their brains during experiments. Parts of the spinal bone were removed and a recording chamber screwed onto the back so that electrodes could be inserted into the spinal cord.

A chemical was injected in multiple areas of the brain to temporarily paralyse the areas that controlled hand movements. The researchers then sent currents down the spinal electrodes to see the effect on the arm and hand muscles in the paralysed monkeys. They assessed the ability of the monkeys to be able to perform reach and grasp movements by presenting pieces of food in front of them when their hand and arm muscles were paralysed. Then they measured their ability to pull a lever in order to get a food reward. The effects of the paralyzing chemical lasted several hours.

In a different experiment, the same research team surgically exposed the spines of four female rhesus monkeys for electrical stimulation. They inserted pairs of steel wires into 14 muscles of the arm and hand. Two of the monkeys had sections of their spine removed to expose the spinal cord, and two had a cut made in their throat, with the oesophagus, trachea and veins moved to one side and muscles cut away for access to the spine which they bore through with a dental drill. Electrodes were placed in different sites of the spine and head, through which an electric current was sent, to record the response in the arm and hands.

This research was a repetition of previous experiments by the same researchers, which they cite as finding the same results as the current study. It is also outlined how electrical stimulation of the spinal cord in patients for chronic pain is an established therapy, so this technique is already being used in humans. Furthermore, a study in patients with chronic spinal cord injury has been carried out, finding that electrical spinal stimulation can improve the hand motor function.

Case study: Cruel gravity experiment on monkeys, Baylor College of Medicine, Texas

Researchers wanted to investigate which cells in the brain respond to gravity. Two macaque monkeys had implants attached to their heads for immobilisation, electrodes inserted into their brain to make recordings, and coils attached to their eyes to measure movements. Monkeys were restrained in chairs inside a motorised spherical enclosed simulator which researchers used to create “sensory conflict”. The monkeys were rotated in different directions 24 times while restrained in the simulator. As well as suffering from the implants in their heads and eyes, monkeys would have experienced stress from being restrained in the chair, placed in the simulator and rotated.

Studies on brain areas associated with the perception of gravity are carried out in humans using non-invasive methods such as fMRI scanning. These include studies which identified the areas of the brain involved, as was the aim of the primate research. The processing of gravity direction in the human brain has been studied extensively in brain damaged patients making invasive experiments on monkeys entirely unjustifiable.

Case study: Chemical eye burning experiments in dogs, College of Veterinary Medicine, Missouri

Seven healthy beagle dogs were sedated and physically manually restrained to obtain scans of the eyes. All of the dogs were sedated and subjected to alkali burns (faster acting than acid burns) on their right eye using a chemical applied for 15-30 seconds, which causes damage and ulceration to the cornea. They were examined daily for 14 days. Once the ulcers had healed on their right eye, dogs received alkali burns to their left eye, but this time the chemical was applied for 30 seconds. After 14 days of examination they were killed so that their corneas could be removed and dissected to examine the scars. The researchers discuss how this experiment has already been carried out in numerous other species, and how it is a frequent injury that humans experience.

The researchers discuss how this experiment has already been carried out in numerous other species, and how it is a frequent injury that humans experience. The researchers claim that in vitro models using cell cultures “fail to replicate the complicated process of wound healing” however, models using human corneal tissue have included a 3D in vitro model which can be used to examine wound healing.

Replacing animals with advanced scientific techniques

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