Primate testing in Europe

Procedures, handling and restraint

Most procedures carried out on primates at HLS require restraint. Capturing monkeys from their cages involves a technician placing a gloved hand in the animal’s cage and waiting until it either moves to the front of the cage or attacks the gloved hand, at which point the monkey is grabbed. Three workers are needed; two to hold the animal, one to perform the procedure. This allows routine procedures such as blood sampling, dosing of product under skin or into muscles, oral dosing (gavage dosing), temperature recording and tattooing. The monkey’s arms, legs and tail will be held and the animal may be held face up or face down. For inhalation dosing and blood pressure recording, animals are strapped into restraint chairs.

Two animals in study JLY0120 were not dosed as one of them suffered repeated prolapses and was to be replaced[115]. Three monkeys suffered rectal prolapses during an incontinence drug study[116]. Rectal prolapse is known to be indicative of gross stress in restrained non-human primates[117].

In addition to being distressing for the animal, handling and restraint is where there are likely to be problems in the human monkey interaction. For example, a member of staff was bitten whilst catching a monkey on the diabetes drug test; as the animal was biting him, he grabbed its head and twisted it (he was subsequently moved to another unit)[118]. Aggression from workers caused by mishandling and fear in the animals, highlights the need for a higher level of supervision and training of staff working with primates[117].

It is clear that HLS management needs to invest more money, time and effort to increase supervision, improve facilities and implement a training programme for the staff and animals – it is recommended that, “Well-trained, competent and motivated personnel can make an enormous difference in improving the welfare of captive primates. The institution should ensure that people caring for and using primates are properly trained and exercise high standards of humane care and treatment”[56].

Reducing stress and suffering during routine procedures

Others working with primates elsewhere, have devised ways of reducing stress and unnatural physical contact the animals are forced to endure:

Oral dosing

Oral dosing (gavage dosing), involves forcing a rubber tube down an animal’s throat; the test compound is injected or pumped down the tube, into the stomach. Our video shows three people holding a small monkey for this procedure, and it is clearly afraid and in great distress[119]. One is holding the arms, another the legs, and a third worker is feeding the tube down the animal’s throat. Yet instead of this, HLS could use a dough type feed into which the compound has been inserted. A recent study reported “Because consumption is voluntary, it is entirely stress free, unlike gavaging…In all cases, the purpose of the study was achieved, even during pharmacokinetic studies where immediate ingestion of the material is critical”[120].

Blood sampling

Blood sampling can also be made less stressful through training. “It takes a cumulative total of about 1 hr to train an adult female or adult male rhesus macaque successfully to present a leg voluntarily and accept venipuncture in the home cage”[121].

Studies of welfare and best practice in management of primate facilities, have recommended “facility managers and principal investigators must ensure appropriate staff levels and sufficient time for training before studies begin, and consider how they can best support their staff to work with co-operative, trained animals rather than resisting, fearful, ones”[122].

Stress from handling and from anticipation of procedures

There is no doubt that monkeys subjected to procedures on a daily basis suffer increased stress and anxiety, which can affect experimental outcomes: “Studies demonstrate that there are long-term consequences of monkeys’ experiences with experimental protocols, such that they may develop cognitive expectations about procedures that affect the data collected compared with experimentally naive subjects”[60].

During the incontinence drug study, several animals suffered rectal prolapses. On 18.06.07, one animal prolapsed during dosing and a technician attempted to help the animal by trying to re-insert the prolapse with a bottle spout but was unsuccessful, and the veterinary surgeon was called[123,124]. The level of anxiety that can cause this condition is well known: “Being removed from the familiar homecage during most restraint situations adds to the anxiety experienced and subjects often show gross signs of distress such as acute diarrhoea, rectal prolapse and alarm vocalization” [our emphasis][117].

For an animal to experience sufficient stress to trigger a rectal prolapse, is a significant event which should be acted upon promptly. Clearly, HLS needed to take action on these incidents. The scientific literature advises a number of behaviours that are used to determine psychological distress, and these include “an increase in disease processes, e.g. diarrhoea and rectal prolapse”[125].

Others have noted that stress in laboratory animals can affect experimental outcomes, and this can arise from anticipation of procedures, too: “Stress responses in the animal result in the release of hormones and other substances to counteract the stress, which can cause anomalous experimental results”[126], and, “the expectations of these animals anticipating daily capture, manhandling and dosing can also impact on test data”[60].

Even events which staff may consider routine can be a source of stress to the monkeys, “stressful housing conditions, loud noises, restraint, sensory deprivation, and separation from companions function similarly to electric shock to hamper the antibody response to bacterial and viral infections and possibly to worsen parasitic infestations”[127].

Expert advice is that it is important to consider that each animal being used is an individual being. “We cannot consider our experimental subjects to be uniform test tubes to which we add our experimental reagents. We must consider the social context, species differences, and individual differences…Failure to do so will result in welfare procedures that do not work and research results that are uninterpretable”[60].

Unfortunately, commercial contract testing laboratories like HLS are based upon high throughput rather than assessing the needs of individuals. The emphasis is, inevitably, on processing large numbers of test compounds, using large numbers of animals. We would submit that this can only lead to poor data.

This makes it all the more vital that scrutiny of project licences for commercial regulatory testing is carefully managed, and that group authorisations are not allowed.

During oral dosing study SOI/0052, several animals suffered from vomiting and salivation on numerous occasions[128-130]. Several monkeys produced black-stained urine on their cage floor[131]. One almost chewed off its finger, gnawing into bone, and continued chewing the hand after it had been dressed by the vet. Others were showing symptoms and behaviours such as tugging at chest skin, pushing their fists into their mouths, trying to bite through the metal food hopper, pushing large amounts of sawdust into cheek pouches, chewing metal and dragging teeth along the bars of the cage[132] and also, five days later, showed signs of twitchy feet, indicating a kind of pins and needles sensation[133,134]. Several animals were clearly distressed yet they were orally dosed as normal and returned to their cages.
At around the same time, a study of the same product was started in rats and researchers had noticed the rats chewing their feet and eating sawdust[132,134]. Almost chewing off a finger is a very significant clinical sign, causing substantial pain, so as a result, the dose for one group was lowered.

Such events illustrate how predictive severity banding (which was not higher than moderate in this case) can often be wrong and that a new system incorporating retrospective review of such studies would better inform future tests as well as improve animal welfare protection.

An inhalation study provided another example of how the severity of a procedure can be misjudged: Over a period of time three monkeys on an inhalation study died or had to be killed due to partially collapsed and blocked lungs. Three other animals also collapsed but were revived. Necropsied animals were found to have blackened lungs[135-140]. Clearly these animals would have suffered a great deal. Due to the severity of the problems and unexpected deaths an internal meeting was held where licensing implications were discussed[137], as this study was licensed under a ‘mild’ severity limit protocol.

Home Office regulations stipulate “The project licence condition will be regarded as breached if the Home Office is not notified promptly…when a protected animal has… suffered (or is likely to suffer) more than is authorised by the severity limit”[141].

The first animal to suffer a severe effect (death) had died three weeks before the meeting to discuss the implications related to the severity banding of the licence. Consequently animals continued to suffer significantly beyond the severity banding on the licence, which in our view, represents a breach of the licence conditions.

It is shocking that the monkeys must have been aware of what was happening around them, as our video shows procedures being performed in front of cages of monkeys[142], and the investigator noted how the monkeys would go silent on the days of the killings and necropsies[143].