The Three "R"s of humane experimental technique are:
Distress may be inflicted directly, as an unavoidable consequence of the experimental procedure employed, or contingently, as an inadvertent by-product of the use of the procedure, which is not necessary for its success, and is always detrimental to the object of the experiment. The incidence of contingent distress "will include the results of every conceivable kind of imperfection in the husbandry of laboratory animals," of which their housing is a major component. "Where chronic experiments over days or months are concerned, we cannot even in principle separate husbandry from the conduct of the experiment itself. For husbandry means keeping the animals alive and healthy for long periods, and this is an essential part of, say, a nutritional experiment" (Russell and Burch, 1959). "Maintenance methods must always be considered as a critical factor in animal experiments, and they must be documented in detail in the experimental design" (Claassen, 1994). It follows that the third "R" - Refinement - is concerned not only with minimising distress during experiments [e.g., by the use of analgesics], but with maximising comfort and well-being of the animals in husbandry.
The reasons for this are not only humanitarian. In all contexts, there is positive correlation between humaneness and scientific efficiency - good science is humane science (Russell and Burch, 1959) - but this is particularly obvious in the present context. The point has been made again and again: "Stressed animals do not make good research subjects" (American Medical Association, 1992; cited by Reinhardt and Reinhardt, 2000). "Good animal experimentation requires consideration not only of temperature and cleanliness, but also of social environment and environmental change. If these direct influences on experiments remain unrecognised or uncontrolled, the validity of research on such animals is to be questioned" (Anonymous, 1974). Or we may go back to the supreme pioneer of our subject, Charles Hume (cited by Poole, 1999): "It fortunately happens that the animals most suitable for scientific research are those that are healthy, tame, comfortable and contented."
Mental or behavioural content is as important as bodily comfort; in fact the two are inseparable. "The major discovery of anatomy and physiology in the last half-century has been that of the extraordinarily subtle, comprehensive and intimate linkages and interactions between the somatic nervous system, the organ of behaviour, the autonomic nervous system and the endocrine system, which control events within the body" (Russell and Burch, 1959). It was already clear in the 1950s which parts of the brain were chiefly involved in these linkages - the hypothalamus in all vertebrates and the limbic system in mammals. These connections are capable of "converting distress caused by the physical or social environment into physiological stress bound to disturb any experimental results. .. More is known now about the pathways to and from the limbic system, and the corticotropin-releasing factor in the hypothalamus, discovered in 1955, was isolated in 1981 and has since been the subject of numerous studies - some in vitro - and related substances have been found in lower vertebrates. All such findings have served only to amplify and fully confirm the very close linkages between the three systems already established in the 1950s" (Russell, 1997). In man this is the basis for the discipline of psychosomatic medicine, equally important in the veterinary context. Disturbances in behaviour, even if they appear to us quite slight, cause mental distress and hence physiological stress.
With all this in mind, we
can now consider some of the ill-effects of various defects in
the physical, behavioural and social environments of laboratory
animals. These ill-effects from unsatisfactory husbandry and housing
will evidently be equally harmful to animal welfare and biomedical
science.
We can begin with light. "Rats, mice and rabbits are nocturnal or crepuscular" (Rose, 1994). Strong light may be harmful for them. When cages are piled in racks, there may be considerable differences among them in light intensity (Bellhorn, 1980). The ones at the bottom can find shaded areas, the ones at the top can only avoid excessive illumination by huddling under the food hopper (Rose, 1994). Strong light can increase adrenal weight in male rats and cause an increase in pre-weaning mortality in mice (Fox, 1986). Even a moderate light intensity can damage the rat retina, and even blind albino rats, who lack a protective retinal pigment (Weihe, 1976; Fox, 1986; Rose, 1994; Clough, 1999). Conversely, herbivorous lizards who lack direct access to sunlight may suffer Vitamin D3 deficiency unless ultraviolet light is artificially provided (Kreger, 1997). Rather surprisingly, some fish in outdoor ponds are liable to be sun-burned, unless protected from excess sunlight (Reddacliff, 1994). This raises the obvious but important point that different species have different needs, and that a knowledge of the life and behaviour of a particular species in the wild is invaluable when designing its laboratory environment.
"Loud sounds, audible to humans, raise triglyceride levels and blood pressure while lowering glucose levels in rats. In rats, mice and hamsters, they cause convulsions" (Russell, 1997). They can damage the cochlea of guinea-pigs, and cause atherosclerosis in rabbits (Fox, 1986). "Sudden noises, such as the clatter of metal cages being cleaned, can cause a 100-200 percent increase in plasma corticosterone in rats" (Fox, 1986).
Some species can hear ultrasounds, and "ultrasounds may be a common feature of the laboratory and animal house environment. Of 39 sound sources monitored, 24 were found to generate ultrasound" (Sales et al., 1989). Examples are cage washers, vacuum hoses, high pressure hoses, ringing telephones, running taps, oscilloscopes, and video and computer monitors, which "gave particular cause for concern as they were entirely ultrasonic and therefore appeared to be `silent'"(Sales et al., 1989). "Ultrasounds increase sodium excretion and may damage the cochlea in rodents" (Russell, 1997). A very important aspect of the ill-effects of loud sounds is that "resulting effects can include atypical responses to drugs many weeks or months after the sound exposure occurs" (Clough, 1999).
While light and sound will
suffice as examples, obviously other physical variables are important,
such as temperature and relative humidity. For instance "large
[10-fold] variations in toxicity can occur with only small [4ºC]
changes in ambient temperature during the course of an experiment"
on the cardiotoxicity of isoprenaline in rats. Low relative humidity
promotes ringtail disease in rats (Clough, 1999). Obviously in
the husbandry of aquatic species correct properties of the water
are vital (temperature, pH, dissolved oxygen, etc.; Gilman, 1984).
In 1962, the Swiss zoologist Ernst Inhelder studied a number of different animal species kept in impoverished environments, that is, simple cages or enclosures with none of the varied features and objects encountered by these species in the wild (Inhelder, 1962). It is worth pointing out that simulations of such features can be perfectly satisfactory. Heini Hediger, the distinguished ethologist and director of the Zürich Zoo, when in Africa, noticed that termite nests had their tops polished or rubbed away, because zebras came from miles away to rub against them as an important means of grooming their coats. On return he set up a cement model of a termite nest in the zebra enclosure of his zoo. The animals were so excited that they rushed to the "nest" and rubbed against it with such enthusiasm they knocked it over! Hediger made a reinforced model, which, he reported, "has been in daily use ever since" (Hediger, 1955).
The animals studied by Inhelder, less fortunate in their totally impoverished environments, had no opportunity to carry out many of their species-typical behaviour patterns, for lack of environmental features or objects to use. In these conditions they carried out instead repetitive stereotyped meaningless activities, such as walking back and forth a short distance so precisely as literally to tread in their own footsteps. This stereotypy resembles the human mental illness of compulsion neurosis, in which the sufferer feels compelled to repeat over and over again some act such as turning a gas jet off and on, or opening and closing a window (Fenichel, 1945). All accounts of this condition agree in showing that it is extremely distressing for the sufferer (Fenichel, 1945; Pfister, 1948; Freud, 1950). We may assume that stereotyped activity is equally distressing for the animals.
Inhelder's studies were made in zoos, but similar observations have been made on laboratory animals. Stereotyped activities in impoverished laboratory environments have been observed in rabbits (head swaying, biting bars, circling walk, pushing hopper with head, etc.; Morton et al., 1993), carnivores ("rocking, pacing, weaving and whirling"; Fox, 1986), rodents (Baenninger, 1967; Wiedenmayer, 1987; Würbel et al., 1998; Callard et al., 2000; Reinhardt and Reinhardt, 2001a), primates (Erwin and Deni, 1979; Poole, 1988; Harris, 1989) and birds (Morris, 1966). Increasing the cage size does not reduce stereotypy (Bayne and McCully, 1989; Galef and Durlach, 1993), but there is actually no reason why it should - an unfurnished large cage is just as impoverished an environment as an unfurnished small cage (Reinhardt and Reinhardt, 2001a). If cages are enriched with furnishings, large ones are better because they enhance the animals' behavioural health (Brent, 1992; Kitchen and Martin, 1996; Williams et al., 2000). In macaques and baboons, stereotypy is reduced or stopped by supplying "one or more perches ... and other cage furniture," especially "a woodchip substrate which includes food items ... as provisioned substrate for foraging" (Harris, 1989). The benefits of such enrichment show that the stereotypy is due to lack of opportunities for carrying out normal behaviour patterns, such as climbing, perching, foraging etc.
Since stereotypy is distressing, we must expect physiological repercussions of impoverishment. Sure enough, gerbils in an impoverished environment have higher cortisol levels than those in an enriched one (van de Weerd et al., 1996). An interesting comparison has been made between mice in a totally impoverished environment and mice supplied with materials they can use to make nests (van de Weerd et al., 1996). The mice in impoverished conditions ate more but weighed less than those supplied with nest materials, probably because they could not regulate their body temperature - by sleeping in a nest - without consuming more food.
We have seen that in rat-cage
racks the rats at the top may get too much light. In double-tier
macaque housing the monkeys in the lower cages may be in such
dim light that "animal care staff routinely use flashlights
to identify animals" (Reinhardt and Reinhardt, 2001b). Except
for owl monkeys, apes and monkeys in general are active in daylight.
A dark cage is as impoverished an environment for them as a dark
dungeon for a human being. Not surprisingly, they show stereotyped
acts in this situation.
In social animals, including many mammal species, the social environment may be unsatisfactory in two different ways: crowding [too many animals in a given area] or isolation [animals caged singly]. Claire Russell and I described the many kinds of behaviour disturbance that occur in crowded and isolated monkeys (Russell and Russell, 1985). There is excessive frequency and intensity of several kinds of conflict activities, acts that in relaxed spacious conditions resolve momentary conflicts, but under crowding or isolation become repetitive and stressful. Under crowding these acts are socially disturbing, for instance rough grooming, or kidnapping babies. Under isolation, they tend to be self-directed - for obvious reasons - for instance repetitive stereotyped self-grooming in adults, or violent self-rocking in young monkeys [instead of the smooth motion of being carried by an adult].
However, the most prominent consequence of crowding or isolation for behaviour is violence. Under crowding conditions this means social violence, including the killing of females and young in particular. We showed that this change in behaviour, and the resulting physiological effects to be considered presently, are aspects of an overpopulation crisis response - a means of reducing populations before they deplete their resources (Russell and Russell, 1968, 1984, 1999). But of course this does not mean it is agreeable for the monkeys. Isolated monkeys redirect violence against themselves. They "pinch the same patch of their own skin repeatedly until it is raw, or even bite and tear themselves" (Russell and Russell, 1985). "Approximately 10% of captive, individually-housed monkeys engage in the disturbing phenomenon of self-injurious behavior" (Jorgensen et al., 1996) with self-inflicted lacerations needing veterinary attention. It has been estimated that there are approximately 15,000 individually-caged macaques in the United States alone, so that as many as 1,500 may be seriously injuring themselves (Reinhardt and Rossell, 2001).
Besides wounds inflicted by others [under crowding] or by themselves [under isolation], crowded and isolated animals are physiologically impaired. By its action on the adrenal glands, crowding causes "not only stress diseases but increased susceptibility to poisons, radiation, parasites and infections" (Russell, 1997). Evidence of the physiological effects of crowding "is available for mice, rats, woodchucks, rabbits, dogs and sika deer" (Russell and Russell, 1968).
Isolation also affects the adrenal glands, and it can cause excessive eating and drinking in rhesus monkeys, decreased leukocyte counts in mice, decrease in circulating lymphocytes and alterations in response to drugs and poisons in rats (Fox, 1986). Isolation can also cause increased blood pressure and hypertension in rats (Claassen, 1994). In macaques, it can increase the susceptibility to diarrhea and promote the development of coronary atherosclerosis (Shively et al., 1989; Schapiro et al., 2000). "Caging monkeys in isolation causes a decline in the number and function of the T cells so vital for immunity, and they recover when the monkeys are restored to their companions" (Russell, 1999). It will be obvious by now that many if not most singly-caged social animals, including the 15,000 macaques, are virtually useless for scientifically sound experimental purposes.
There is one final interesting
point about the social environment. In 1956, Michael Chance studied
the test response of immature female rats to serum gonadotrophin,
and found that "the variation in ovary weight [the test response]
was greater if the rats were caged either singly or in
groups larger than two [with the floor area per rat roughly constant]"
(Chance and Russell, 1997). In 1992, Chance's colleague John Mackintosh
obtained a similar result in a study of the response of male mice
to a barbiturate anaesthetic. It follows that an optimal social
environment can make animals more uniform, and the less animals
vary in their responses the fewer of them we need to get a statistically
representative sample. Here, therefore, reduction goes hand in
hand with refinement.
There are a number of routine
procedures that form part of many experiments: physiological monitoring,
drug administration and blood collection. These can be carried
out without restraining the animals or moving them from their
home cage, by telemetry (Brockway et al., 1993; Schnell and Wood,
1993; Kramer, 2000) or training, for instance teaching primates
actively to cooperate during injection and venipuncture in their
homecage (Priest, 1991; Reinhardt and Cowley, 1992). Unfortunately,
instead of these refinements being used, animals are often transferred
from their cages to some other place, where they are put under
enforced restraint for these procedures. "Transfers between
cages or containers raise corticosterone levels and cause weight
loss in mice, and raise catecholamine and other hormone levels
and susceptibility to the poison ammonium diuranate in rats. Simple
tethering raises the heart rate in cynomolgus monkeys. More severe
physical restraint raises the blood pressure in rats and mice,
catecholamine levels in rats, and rectal temperature and pulse
rate in golden marmosets. In rats, it can also affect numbers
of receptors at certain sites and therefore directly affect responses
to drugs" (Russell, 1997). In several species enforced immobilization
can produce gastric ulceration (Fox, 1986).
From all these findings, it will now be obvious that the provision of comfortable quarters - including handling procedures - with a stable environment, companionship, and freedom to engage in the species-typical basic activities, is of supreme importance, alike for laboratory animal welfare and for the progress of reliable biomedical science.
American Medical Association 1992. Use of Animals in Biomedical Research - The Challenge and Response - An American Medical Association White Paper. AMA. Group on Science and Technology, Chicago, IL (Cited by Reinhardt and Reinhardt, 2000)
Anonymous 1974. Review of Environmental Variables in Animal Experimentation (edited by Magalhaes, H), Bucknell University Press, Lewisburg, PA. ILAR [Institute of Laboratory Animal Resources] News 18(1), 20
Baenninger LP 1967. Comparison of behavioural development in socially isolated and grouped rats. Animal Behaviour 15, 312-323
Bellhorn RW 1980. Lighting in the animal environment. Laboratory Animal Science 30, 440-450
Brent L 1992. The effects of cage size and pair housing on the behavior of captive chimpanzees. American Journal of Primatology 27, 20
Brockway BP, Hassler CR, Hicks N 1993. Minimizing stress during physiological monitoring. In Refinement and Reduction in Animal Testing Niemi SM, Willson JE (eds), 56-69. Scientists Center for Animal Welfare, Bethesda, MD
Callard MD, Bursten SN, Price EO 2000. Repetitive backflipping behaviour in captive roof rats (Rattus rattus) and the effect of cage enrichment. Animal Welfare 9, 139-152
Chance MRA, Russell WMS 1997. The benefits of giving experimental animals the best possible environment. In Comfortable Quarters for Laboratory Animals, Eighth Edition Reinhardt V (ed), 12-14. Animal Welfare Institute, Washington, DC
Claassen V 1994. Neglected Factors in Pharmacology and Neuroscience Research. Elsevier, Amsterdam, Netherlands
Clough G 1999. The animal house: design, equipment and environmental control. In UFAW Handbook on the Care and Management of Laboratory Animals, Seventh Edition, Volume 1 Poole T, English P (eds), 97-134. Blackwell Science, Oxford, UK
Erwin J, Deni R 1979. Strangers in a strange land: Abnormal behavior or abnormal environments? In Captivity and Behavior Erwin J, Maple T, Mitchell G (eds), 1-28. Van Nostrand Reinhold, New York, NY
Fenichel O 1945. The Psychoanalytical Theory of Neurosis WW Norton, New York, NY
Fox MW 1986. Laboratory Animal Husbandry: Ethology, Welfare and Experimental Variables. State University of New York Press, Albany, NY
Freud S 1950. Notes upon a case of obsessional neurosis (1909). In Collected Papers, Volume 3, 291-383. Hogarth Press and Institute of Psychoanalysis, London, UK
Galef Jr. BG, Durlach P 1993. Should large rats be housed in large cages? An empirical issue. Canadian Psychology 34, 203-207
Gilman J (ed.) 1984. Guide
to the Care and Use of Experimental Animals, Volume 2 Canadian
Council on Animal Care, Ottawa, Ontario, Canada
Full Text: http://www.ccac.ca/guides/english/toc_v2.htm
Harris DHR 1989. Environmental enrichment and its effects on the individual. In Laboratory Animal Welfare Research - Primates Universities Federation for Animal Welfare [UFAW] (ed), 15-16. UFAW, Potters Bar, UK
Hediger H 1955. Studies of the Psychology and Behaviour of Captive Animals in Zoos and Circuses. Butterworths Scientific Publications, London, UK
Inhelder E 1962. Skizzen zu einer Verhaltenspathologie reaktiver Störungen bei Tieren. Schweizer Archiv für Neurologie, Neurochirurgie und Psychiatrie 89, 276-326
Jorgensen MJ, Novak MA, Kinsey J, Tiefenbacher S, Meyer JS 1996. Correlates of self-injurious behavior in monkeys. XVIth Congress of the International Primatological Society/XIXth Conference of the American Society of Primatologists, Abstract No. 767
Jorgensen MJ, Kinsey JH, Novak MA 1998. Risk factors for self-injurious behavior in captive rhesus monkeys (Macaca mulatta). American Journal of Primatology 45, 187
Kramer K 2000. Applications and Evaluation of Radio-Telemetry in Small Laboratory Animals. Doctoral Thesis, University of Utrecht, Utrecht, Netherlands
Kreger MD 1997. Laboratory
housing for reptiles and amphibians. In Comfortable Quarters
for Laboratory Animals, Eighth Edition Reinhardt V (ed), 32-40.
Animal Welfare Institute, Washington, DC
Full Text: http://www.awionline.org/pubs/cq/three.pdf
Kitchen AM, Martin AA 1996.
The effects of cage size and complexity on the behaviour of captive
common marmosets, Callithrix jacchus jacchus. Laboratory
Animals 30, 317-326
Full Text: http://www.lal.org.uk/pdf.htm
Morris D 1966. Abnormal rituals in stress situations: the rigidifaction of behaviour. Philosophical Transactions of the Royal Society Series B 251, 327-330
Morton DB, Jennings M, Batchelor
GR, Bell D, Birke L, Davies K, Eveleigh JR, Gunn D, Heath M, Howard
B, Koder P, Phillips J, Poole T, Sainsbury AW, Sales GD, Smith
DJA, Stauffacher M, Turner RJ 1993. Refinements in rabbit husbandry.
Second report of the BVAAWF/FRAME/RSPCA/UFAW joint working group
on refinement. Laboratory Animals 27, 301-329
Full Text: http://www.lal.org.uk/pdffiles/rabbit.pdf
Pfister O 1948. Christianity and Fear Allen & Unwin, London, UK (Transl. Johnston WH)
Poole TB 1988. Normal and abnormal behaviour in captive primates. Primate Report 22, 3-12
Poole T 1999. Introduction. In UFAW Handbook on the Care and Management of Laboratory Animals, Seventh Edition, Volume 1 Poole T, English P (eds), 1-3. Blackwell Science, Oxford, UK
Priest GM 1991. Training
a diabetic drill (Mandrillus leucophaeus) to accept insulin
injections and venipuncture. Laboratory Primate Newsletter
30(1), 1-4
Full Text: http://www.brown.edu/Research/Primate/lpn30-1.html#loon
Reddacliff GL 1994. Examples of species-specific considerations in the design of an environment - fish. In Improving the Well-being of Animals in the Research Environment Baker RM, Jenkin G, Mellor DJ (eds), 135-138. ANZCCART [Australian and New Zealand Council for the Care of Animals in Research and Teaching], Glen Osmond, SA, Australia
Reinhardt V, Cowley D 1992.
In-homecage blood collection from conscious stumptailed macaques.
Animal Welfare 1, 249-255
Full Text: http://www.awionline.org/Lab_animals/biblio/aw1blood.htm
Reinhardt V, Reinhardt A
2000. Blood collection procedure of laboratory primates: A neglected
variable in biomedical resarch. Journal of Applied Animal Welfare
Science 3, 321-333
Full Text: http://www.awionline.org/Lab_animals/biblio/jaaws2.html
Reinhardt V, Reinhardt A
2001a. Legal space requirement stipulations for animals in the
laboratory: Are they adequate? Journal of Applied Animal Welfare
Science 4, 143-149
Full Text: http://www.awionline.org/Lab_animals/biblio/jaaws3.html
Reinhardt V, Reinhardt A
2001b. Environmental Enrichment for Caged Rhesus Macaques (Macaca
mulatta) - Photographic Documentation and Literature Review
(Second Edition). Animal Welfare Institute, Washington, DC
Full Text: http://www.awionline.org/lab_animals/rhesus/Photo.htm
Reinhardt V, Rossell M 2001.
Self-biting in caged macaques: Cause, effect and treatment. Journal
of Applied Animal Welfare Science 4, 285-294
Full Text: http://www.awionline.org/Lab_animals/biblio/jaaws4.html
Rose MA 1994. Environmental factors likely to impact on animal's well-being - an overview. In Improving the Well-being of Animals in the Research Environment Baker RM, Jenkin G, Mellor DJ (eds), 99-116. ANZCCART [Australian and New Zealand Council for the Care of Animals in Research and Teaching], Glen Osmond, SA, Australia
Russell C, Russell WMS 1968. Violence, Monkeys and Man. Macmillan, London, UK
Russell C, Russell WMS 1984. Overpopulation crisis. Social Biology and Human Affairs 49, 23-42
Russell C, Russell WMS 1985. Conflict activities in monkeys. Social Biology and Human Affairs 50, 26-48
Russell C, Russell WMS 1999. Population Crises and Population Cycles. The Galton Institute, London, UK
Russell WMS 1997. Shooting the clock: Timeless lessons of the past still guide today's refinement initiatives. Science and Animal Care [WARDS Newsletter] 8(3), 1-2 & insert
Russell, WMS 1999. Reduction and refinement in biomedical experiments. Research Defence Society [RDS] News January, 12-13
Russell WMS, Burch RL 1959.
The Principles of Humane Experimental Technique. Methuen,
London, UK
Full Text: http://altweb.jhsph.edu/publications/humane_exp/het-toc.htm
Sales GD 1989. Effects of environmental ultrasound on behaviour of laboratory rats. In Laboratory Animal Welfare Research - Rodents Universities Federation for Animal Welfare [UFAW] (ed), 7-16. UFAW, Potters Bar, UK
Schapiro SJ, Nehete PN, Perlman JE, Sastry KJ 2000. A comparison of cell-mediated immune responses in rhesus macaques housed singly, in pairs, or in groups . Applied Animal Behaviour Science 68, 67-84
Schnell CR, Wood JM 1993. Measurement of blood pressure, heart rate, body temperature, ECG and activity by telemetry in conscious unrestrained marmosets. Proceedings of the Fifth Federation of European Laboratory Animal Science Associations (FELASA) Symposium , 107-111
Shively CA, Clarkson TB, Kaplan JR 1989. Social deprivation and coronary artery atherosclerosis in female cynomolgus monkeys. Atherosclerosis 77, 69-76
van de Weerd HA, van Loo PLP, van Zutphen LFM, Koolhaas JM, Baumans V 1996. Long-term behavioural and physiological effects of nesting material as environmental enrichment for laboratory mice. In Environmental Enrichment for Laboratory Mice: Preferences and Consequences van de Weerd, 87-104. Doctoral Thesis, University of Utrecht, Netherlands
Weihe WH 1976. The effect of light on animals. Laboratory Animal Handbooks 7, 63-76
Wiedenmayer C 1997. The early ontogeny of bar-gnawing in laboratory gerbils. Animal Welfare 6, 273-277
Williams LE, Steadman A, Kyser B 2000. Increased cage size affects Aotus time budgets and partner distances. American Journal of Primatology 51, Supplement 1, 98
Würbel H, Chapman R,
Rutland C 1998. Effect of feed and environmental enrichment on
development of stereotypic wire-gnawing in laboratory mice. Applied
Animal Behaviour Science 60, 69-81
William M.S. Russell is a zoologist who, with the late Rex L. Burch, when working for UFAW published in 1959 The Principles of Humane Experimental Technique, the pioneering book for animal welfare research that introduced the Three Rs: replacement of conscious animals by insentient material, reduction of numbers of animals used to obtain given information, and refinement of procedures to minimize the distress imposed on the animals still used. Since 1990 William Russell has been Emeritus Professor at the Department of Sociology, University of Reading; he remains actively involved in laboratory animal science and welfare.