That animals are well treated is a concern of any civilized society.
Some believe that animals have rights that are equal to human rights, ie that there is no fundamental difference between humans and animals. Consequently, any human use of animals, including pet owner ship, is wrong. Obviously this view eliminates performing research on animals.
Others believe that humans occupy a higher position than animals and are thus entitled to own, use and keep animals as pets. This is the prevailing view in our society at the moment. However, most proponents of this position believe that it carries a responsibility to make sure that animals in our care are free from distress and that they are content. In other words that their welfare is taken care of. They feel it is imperative, therefore, that animals used in research are especially well cared for, given that they may be exposed, under some circumstances, to painful or even lethal procedures. This view of animal welfare relating to animals in research is the focus of this lecture.
It is therefore essential to make sure that all procedures performed on animals do not cause pain or distress unless it is absolutely necessary. For most animals used in research this means modifying experimental design to take into account animal welfare. In 1959 Russell and Burche's classic book called The Principles of Humane Experimental Technique outlined the "three R's" of animal experimentation, namely Replacement, Reduction and Refinement.
Replacement means replacing the animal model with some other technique, such as an in vitro model, eg tissue culture.
Reduction means using as few animals as possible in the study, without compromizing the validity of the study.
Refinement means designing studies which inflict as little pain or discomfort as possible.
Peoples concerns about animal welfare led to legislation first by the animal loving British.
People were experimenting on animals without any limits place on their activities.
This was a stated purpose of the bill. This legislation predates equivalent legislation in the US by about a century.
Among its many provisions the 1876 Act indicated that one could not peform experiments on aniamls without some form of certification.
The USA was suprisingly slow to adopt laws governing animals in research
Because of the long ride endured by cattle, sheep and swine from the plains to the slaughter houses, laws were passed limiting the maximum time for an animal to be transported. The federal version of this law became known as the 28 hour law.
This was the first federal law governing care of laboratory animals. It put restrictions on supplies of dogs to research institutions. Lost pets were ending up as research subjects for experimentation. An article in Life magazine increased public attention to the problem of stolen or lost dogs being sold to researchers. However, this act only governed animal care prior to experimentation.
Improved standards for all animals throughout their stay, such as the use of pain relieving drugs. But did not include standards for rats and mice.
Each instituion must have an Institutional Animals Care and Use Committee which reviews proposals involving experimentation on animals. An IACUC proposal of my own is avaialble here.
This is The Guide which all PHS funded institutions use to set up programs to monitor laboratory animal welfare.
The tendency for an animal to maintain behavioral and physiological equilibrium.
Animal is at equilibrium with the environment, and engaging in normal behaviors related to eating, sleeping, social interactions, reproduction, grooming etc.
Animal is experiencing an adverse change in its environment. The animal is forced to adapt to maintain equilibrium.
Stress is the state when an animal's equilibrium is challenged. These challenges are referred to as stressors.
Physiologic stressors include those stresses which arise from an injury to the body in some way or other. They include surgery, disease, starvation, dehydration.
Psychologic stressors arise from situations causing strictly behavioral disturbances, including fear, anxiety, boredom, loneliness and separation.
Environmental stressors are those in which environmental changes challenge the animals ability to maintain homeostasis. Examples include restraint, noise, odors, habitat, people, other animals, chemicals, pheromones.
The animal under stress has to respond in order to maintain homeostasis. An adaptive response is one which brings the animal back to equilibrium.
Distress is the state in which the animal is failing to successfully adapt to stressors. Unable to find relief from the stress the animal may then resort to maladaptive responses.
Maladaptive responses do not relieve the stress nor bring the animal back to homeostasis. Examples include inappropriate eating, sleeping, grooming or reproductive behaviors. Animals may become aggressive, self mutilate, or develop stereotypical movements. Furthermore, pathological conditions, such as gastric ulcers, digestive disturbance or immunosuppression may result.
Nociception is the detection of pain by the nervous system, but does not necessarily imply perception by the conscious animal. A withdrawal reflex may be elicited by a noxious stimulus to a limb, but the animal may not perceive the pain.
Nociperception is the conscious perception of pain. The animal consciously feels pain, and may, if able, respond appropriately by crying out, fleeing, starting, struggling etc.
Pain threshold is the level at which a stimulus becomes painful. For example, pressure applied to the skin at first is touch, but then becomes painful as the intensity increases. The pain threshold is crossed when touch becomes painful.
Pain tolerance is the highest level of pain that can be borne voluntarily. An example is when you have a headache and for some reason are determined not to take any medication. Finally, it gets so bad you give in and take some medication. That's when your pain tolerance is reached for that given stimulus. Obviously pain tolerance will vary greatly depending on the individual, the pain and the situation.
Anxiety and fear are both stressors in themselves, but also may alter pain threshold or tolerance.
Fear tends to be an avoidance of a known noxious stimulus or object. Anxiety is a generalized sense of unease about a situation in which unknown events may unfold. Fear is therefore focused, and anxiety unfocused.
Sometimes anxiety may increase the pain threshold. For instance, procedures may tend to elicit pain at a lower threshold if the procedure is known, feared, and anticipated. In other situations, especially associated with trauma, fight or flight, the pain threshold may be raised greatly in the excitement of escaping or overcoming some threat.
Significant stress may be placed on an animal without directly inflicting pain. The following are examples of stressors which do not induce pain.
"Conspecifics" means members of the same species.
Crowding animals too closely together can induce a stress response.
Isolating an animal can also be stressful. The effect depends on when in life the animal is isolated.
Isolation of a newborn or immature mammal disrupts the maternal infant bond. The animal seeks and requires some form of nurturing. Often, humans supply this nurturing when raising orphan mammals. Mammals raised in isolation often display atypical behaviors, and lack social skills when re-introduced to their own species. Reproductive behavior and function may be severely disrupted in animals raised in isolation. Because young animals may adapt successfully to nurturing by another species, this response may be regarded as adaptive. The stress of such isolation may soon become difficult to detect.
The mature animal is more closely adapted to relationships with conspecifics. Isolating the adult animal can be greatly stressful, depending on the strength of bonds that existed prior to separation. Separation of a monogamous mating pair can be highly stressful. Depending on the species, different animals adapt to separation better than others. For some species, human care takers can provide social interaction as a partial substitute for interaction with an animal's own species. This may help the animal to adapt to separation.
Play, grooming, huddling, or just being together are often normal behaviors of social animals. Being able to act out these normal behaviors usually improves the animal's sense of emotional wellbeing, reducing signs of distress. Highly social animals will probably receive more benefit from such stimulation than species that are solitary by nature. Play and socialization by human caretakers can, under certain circumstances, improve an animal's sense of well being through positive soical stimulation.
Usually laboratory animals are kept away from both predators and prey. However, humans are able to evoke both predatory or prey like responses from laboratory animals. A predatory species may misinterpret human movement or actions as those of a prey animal. This could lead to an "attack" by the animal. Alternatively, failure of a predatory species to act out the behaviors involved in capturing prey might be a source of boredom, and therefore stress for that animal.
Humans may induce defensive, prey like behavior in laboratory animals. Often, humans may appear predatory, causing a fight or flight response in the animals in their care. An animal under constant apprehension of predation could be under considerable stress, especially if daily physical examinations or treatments that the animal received were perceived by the animal as repeated, successful, attacks by a predator. Ugh!
An important part of animal behavior is the building of a nest, or the establishment of territory. Some animals enjoy nest building activities, and the sense of controlling their environment. It is often helpful to provide nest building materials for laboratory animals. However, in some cases, eg rats, it may make the animal overly protective of its territory.
It is also necessary to provide adequate space for the animal, so normal behaviors can be expressed. These include climbing, burrowing, running, claw sharpening, gnawing and normal patterns of urination and defecation.
Feeding behaviors are important parts of an animal's emotional wellbeing, in addition to satisfying nutritional requirements. We enjoy eating out, or having friends over for a meal. Animals also enjoy eating in particular ways. Dogs enjoy gnawing, some primates may enjoy exploring for food, other animals, such as snakes, will only eat live food. Recreating normal feeding behaviors in captivity can greatly improve an animal's welfare.
Generally, animals in captivity have little ability to control their environment. Laboratory housing tends to be sterile and lacking in stimulation. This causes stress due to lack of control and boredom.
Animals, like humans, enjoy a certain degree of control over their environment. This includes the ability to make nests, or to choose areas for shelter or feeding. Animals will adapt better to stressful conditions when given choice or access to materials which give them some control.
Lack of variety can precipitate significant stress. An unchanging environment with no stimulation can precipitate maladaptive behaviors, such as self-mutilation, hair-pulling etc.
Different species display distress differently. It requires some experience and knowledge for a caretaker to be able to detect stress in a given species
Some animals do not show outward sign's of distress, but are nevertheless failing to adapt. This behavior is usually called stoic after the "Stoic" school of philosophers in ancient Greece who prized self-control.
Acute (sudden onset) pain can induce a sudden change in an animal and is usually easier to recognize than chronic (long-lasting) pain. Caretakers can become somewhat desensitized to behavior indicating chronic pain in animals. A new caretaker may recognize chronic pain when he or she take over care of animals from another caretaker.
Each species tends to have a different response to pain.
It is better to manage pain by prevention than by drugs (pharmacologic agents), but drugs should not be witheld if necessary.
Much stress maybe induced my routine management practices. By focusing on altering management to relieve unnecessary pain or distress successful adaptation to the laboratory surroundings can be promoted.
One should review the non-pain sources of stress listed above.
Appropriate group housing to encourage conspecific socialization is important, but must be managed carefully. Inappropriate grouping may increase stress if a stable hierarchy is not formed.
Taking direct steps to improve a laboratory animal's welfare through improved living conditions is called environmental enrichment. It may involve improved relationships with con-specifics, improved housing, introduction of some change in housing which promotes normal behavior, such as feeding, foraging, nesting or types of movement.
It is important for both animal welfare and scientific reasons to minimize stress when designing experiments on laboratory animals. Stressed animals may not respond appropriately to experimental stimuli, yielding spurious results. Conditioning to the experimental routine may be an important part of experimental design. Above all, a refined experimental approach which minimizes distress and pain is to be sought.