 Animal Welfare Information Center NewsletterProvided by the Animal Welfare
Information Center
|
SPRING 1994 VOL. 5, NO1
ISSN: 1050-561X
Animal Welfare Information Center NewsletterProvided by the Animal Welfare
Information Center
|
ISSN: 1050-561X
Welfare Concerns for Farm Animals Used in Agricultural
and Biomedical Research and Teaching
by
Janice C. Swanson, Ph.D.
Department of Animal Science and Industry
Kansas State University
Manhattan, KS
Introduction
Animal welfare issues are often thought to be easily dissipated by the production of scientific arguments and evidence. However, animal welfare is not only a scientific issue. Politics, philosophy and ethics, and aesthetics can influence societal expectations concerning the use, care, and treatment of animals (b). Because of the multiple influences that come to bear on the issue, it is nearly impossible to reach agreement on a precise definition of animal welfare (6,9). However, there seems to be a general consensus that there are two central themes, the state of the animal itself and broader sociological factors. An approach used within the scientific community is to use the term þanimal well-beingþ when referring to the actual welfare status of the animal, and þanimal welfareþ when referring to broader sociological and ethical concerns (5). When encountering concerns regarding farm animal use in research and teaching, there is a need to address the broader sociological and ethical expectations as well as the scientific.
Agricultural Research and Teaching
Farm animals used for agricultural research require strict attention to their care, husbandry, and maintenance of protocol requirements under a variety of conditions (a). The research environment may vary from fairly extensive (e.g., grazing study) to very intensive (e.g., metabolism trial). It is expected that the research animals will not be subjected to unnecessary pain or distress and will be observed for the development of signs of distress. Social (e.g., isolation) or physiological (e.g., sensory) deprivation tends to raise concerns and questions about the necessity of the procedure and potential benefits of the research. Agriculture is typically perceived as an applied science and when research protocols require greater manipulation (e.g., invasive procedures) questions arise concerning the potential application of results and the skill of the researcher(s) involved. For example, field or standing surgery often poses questions regarding potential harm to the animal due to lack of aseptic conditions or adequate pain control. Other surgical procedures such as fistulation, laparotomies, cannulation, etc., are sometimes performed by persons other than veterinary surgeons (e.g., trained Ph.D. or graduate students), which present issues concerning proper training and oversight (14). Pre- and post-operative care, pain recognition, and management are critical to animal well-being. Handling, equipment use and condition, and methods that are current with good practice are important from both a research and welfare perspective (7). Concerns often arise when observation notes deficiencies in any of the areas mentioned above and effects on animals are perceived. Teaching in agricultural schools and colleges also presents concerns for the animals and the safety of the students. A wide variety of teaching activities occur from basic þhands-onþ experience such as leading animals to fairly technical physiological laboratories. Handling animals that are relatively large requires that instructors are knowledgeable about the specie with which they are working and safety precautions that need to be considered to protect students and animals. Concerns arise regarding the instructor's competency in animal behavior, husbandry, handling methods,and technical skills. Also of concern are suitability of teaching facilities, holding quarters, transportation to and from instructional sites (if required), equipment, student manipulation, provision of space and essentials such as food and water (if held for long periods). Demonstrations of invasive procedures in upper level techniques courses require instructors to be sensitive to animal needs and student concerns. Euthanatization techniques should be in accordance with the American Veterinary Medical Association's recommendations for approved methods of euthanasia (15). Instructors should be familiar with state-of-the-art methodology and have demonstrated skill in performing the technique before being allowed to teach students. Finally, dedication to exercising the 3 R's (reduction, refinement, and replacement) when working with potentially painful procedures can serve as appropriate guidance for agricultural teaching and research. All teaching and research protocols should be submitted and reviewed by the InstitutionalAnimal Care and Use Committee (IACUC).
Biomedical Research and Teaching
Farm animals have made valuable contributions as models in biomedical research (4,a). Organ transplants, pharmacokinetics, vaccine efficacy, etc., are just a few examples of how farm animals have been used. Special concerns arise when animals who are not customarily bred and raised in laboratory settings are used for experimental manipulations under such conditions. Flooring, housing, isolation, handling, and specialized equipment are all concerns. Experimental manipulations may require extensive contact with the animal for long periods of time, therefore, standard field equipment, traditionally used in agricultural practice for short-term restraint purposes, is not practical in many laboratory settings (11). Frequent handling of the animal and familiarization with equipment and routines may be necessary to alleviate distress in laboratory settings. Surgical facilities (especially for large species such as cattle and horses), proper use of analgesia and anesthetics, and pre- and post-surgical care are of utmost concern. Like agricultural teaching, similar concerns can be echoed regarding the use of farm animals in biomedical teaching. Appropriateness and goals of the exercise, skills of the instructor, techniques used, facilities, etc., should be considered. However, in biomedical teaching it is more likely that the animal will be subject to greater manipulations and invasiveness. The 3 R's are expected to be considered in teaching protocols that are potentially painful. Consideration should be given to reducing the number of animals used, looking for alternative teaching technologies, and using the most appropriate techniques and equipment for the intended purpose.
Compliance standards under the AWA and/or Public Health Service (PHS) policy must be met for farm animals used in biomedical activities. All protocols must be reviewed by the IACUC.
Assessing Farm Animal Well-Being
Assessing the well-being of farm animals requires that adequate measures have been identified and agreed upon, and are quantifiable (b,c). In agricultural settings, farm animal well-being has traditionally been assessed by productivity (e.g., growth, weight gain, feed intake, etc.), various health parameters (e.g., disease incidence), a limited number of physiological measures (e.g., cortisol), and animal behavior (e.g., stereotypies, vacuum behaviors). The science of animal welfare is still in its infancy, and current investigations are revealing the complexities of well-being assessment (9). Researchers, although diverse in their proposals of best measures, are in general agreement that a multi-disciplinary approach is needed to assess and define animal welfare in order to understand, alleviate, and prevent suffering (13). The concept of animal suffering is controversial (2). Duncan (3) suggests that welfare is determined primarily by how an animal þfeels.þ To suffer, animals must 1) be sentient, and 2) have the ability to be aware of their suffering. Research into cognition, perception, motivation, and the emotional states of animals can provide insight into welfare problems. Others, however, suggest that feelings are too subjective to provide reliable information and that more objective measures based on biological functioning, such as a pre-pathological state (8,10), would be more accurate. While welfare assessment is very much in debate, reasonable observations can be made to help assess welfare in research and teaching settings. It is reasonable to assume that animal well-being is of a physiological and psychological nature, and that both need to be monitored to the best of our abilities. Aside from the considerations previously stated, careful observations of the animals and of human-animal interactions can provide helpful feedback. Depression, anorexia, injury, aggressiveness, self-mutilation, sickness, and fear responses can be indications that the animal's psychological and/or physiological well-being is impaired. Thorough knowledge of protocols will assist in determining whether such manifestations are expected (e.g., disease research) and addressed, or unexpected and in need of attention, or worse, symptomatic of neglect and poor research conduct. Animal caretakers, instructors, and researchers all need to develop a keen eye for their animals and address problems in a timely manner.
Public Accountability
During the last 20 years, public concern about the use of animals for experimental and educational purposes has focused on the biomedical community. Federal legislation such as the Animal Welfare Act (AWA) provided impetus behind institutional accountability for the care and use of common laboratory species. Agricultural animals used in biomedical research are covered by the AWA at this time, but with no specific standards for their care and use. If used experimentally for the purpose of improving food or fiber production, they are exempted from the AWA regulation. The Public Health Service (PHS) policy sets standards of care for all warm-blooded vertebrates used in PHS-supported work. General standards of care for common species of livestock are outlined in the National Institutes of Health (NIH) Guide for the Care and Use of Laboratory Animals. Although appropriate for the care of livestock under the experimental settings of biomedicine, the NIH Guide falls short of addressing the unique attributes of agricultural production research (1).
Although general concerns about the well-being of farm animals used in either biomedicine or agriculture can be thought to parallel one another, differences do exist in the goals of agricultural and biomedical research and teaching that require guidelines and standards to maximize welfare to differ (12). Agricultural research must have the ability to use its current industry practices as a control in order to address problems in either a basic or applied sense. The ultimate goal is the production of a food product and practices that can be applied in the field. Although application of the 3 R's has been advocated in agricultural teaching and research, there are limits. Replacement of animals is often not an option and may have limited use in teaching or research protocols. For example, when attempting to answer specific questions concerning specie productivity, no other model will be acceptable. In biomedical research, farm animals are generally used as models for human systems or conditions, and the production or testing of products (pharmaceutical, etc.). There tends to be greater experimental manipulation of the animal in biomedical procedures, and housing and handling requirements are generally more intensive with rigid standards for laboratory upkeep. The experimental criteria for the use of these animals will vary. In the mid-1980's a consortium of animal scientists, members of the government and veterinary community, etc., cooperated to develop the Guide for the Care and Use of Agricultural Animals in Agricultural Research and Teaching. The Ag Guide, as it is presently referred to, is meant to provide institutional accountability, responsibility, and compliance guidelines for farm animals used in agricultural teaching and research. Prior to the publication of the Ag Guide, there was no vehicle by which welfare concerns could be formally addressed, nor uniform guidelines that agricultural institutions could refer to. Presently the Ag Guide has been adopted by a majority of agricultural institutions for setting policy on institutional animal care and use (Mench, personal communication), and the American Association for Accreditation of Laboratory Animal Care has adopted the Ag Guide (specie care and husbandry sections) for accreditation of farm animal research facilities.
Maintaining the welfare of similar animals for different purposes in contrasting environments poses a problem with consistent application of guidelines for their care and use. Hence, the potential utilization of three documents (AWA, NIH Guide, and Ag Guide) to ensure their welfare. IACUC's should be well acquainted with all three documents to know under which conditions each of these documents should be applied.
Conclusion
In closing, I wish to reflect on the idea that no issues would exist if it were not for human concern and commitment to animal welfare. Laws, standards, and guidelines are ways in which the research and teaching community can be held accountable to the public for their actions. Animal protection groups frequently seek to strengthen and provide increased oversight of research activities in an attempt to represent the interests of the animal being used. Whereas, the biomedical and agricultural community seek to reach a compromise between human and animal interests that will provide societal benefits yet fulfill expectations regarding animal care and use. I venture to say that most issues concerning the care and use of animals in research and teaching are propelled by the dynamic exchanges between protectors and users of animals, each of which has made contributions to enhancing farm animal welfare.
Endnote
Listed below are cited literature and selected references of the recent articles and proceedings that address farm animal welfare issues. All have been used extensively for the production of this paper.
Literature Cited
1. Curtis, S.E. (1992). "Agricultural animal guidelines." Proceedings from a SCAW-sponsored conference, Agricultural Animals in Research, held September 6-7, 1990, Washington, DC. Scientist Center for Animal Welfare, Bethesda, MD, pp 11-12.
2. Dawkins, M. S. (1980). Animal Suffering. Chapman Hall, London, pp. 10-26.
3. Duncan, I. J. H. (1993). þWelfare is to do with what animals feel.þ Journal of Agricultural and Environmental Ethics, 6 (Special Suppl. 2):8.
4. Ediger, R.D. (1992). þThe use of farm animals in biomedical research.þ Proceedings from a SCAW-sponsored conference, Agricultural Animals in Research, held September 6-7, 1990, Washington, DC. Scientist Center for Animal Welfare, Bethesda, MD, pp. 51-53.
5. Fraser, D. (1993). þAssessing animal well-being: Common sense, uncommon science.þ Food Animal Well-Being 1993 - Conference Proc. and Deliberations, April 13-15 1993, Indianapolis, IN. Purdue University, Office of Agricultural Research Programs, West Lafayette, IN, pp. 37-54.
6. Gonyou, H. W. (1993). þAnimal welfare: Definitions and assessments.þ Journal of Agricultural and Environmental Ethics, 6(Special Suppl. 2):37.
7. Grandin, T. (1992). þHandling and transport of agricultural animals used in research.þ Proceedings from a SCAW-sponsored conference, Agricultural Animals in Research, held September 6-7, 1990, Washington, DC. Scientist Center for Animal Welfare, Bethesda, MD, pp. 74-84.
8. McGlone, J. (1993). þWhat is animal welfare?þ Journal of Agricultural and Environmental Ethics, 6(Special Suppl. 2):26.
9. Mench, J. A. (1993). þAssessing animal welfare: An overview.þ Journal of Agricultural and Environmental Ethics, 6(Special Suppl. 2):68.
10. Moberg, G. P. (1993). þUsing risk assessment to define domestic animal welfare.þ Journal of Agricultural and Environmental Ethics, 6(Special Suppl. 2):1.
11. Panepinto, L.M. (1992). þThe minimum-stress physical restraint of swine and sheep in the laboratory.þ Proceedings from a SCAW-sponsored conference, Agricultural Animals in Research, held September 6-7, 1990, Washington, DC. Scientist Center for Animal Welfare, Bethesda, MD, pp. 85-87.
12. Stricklin, W.R., D. Purcell and J.A. Mench. (1992). þFarm animals in agricultural and biomedical research.þ Proceedings from a SCAW-sponsored conference, Agricultural Animals in Research, held September 6-7, 1990, Washington, DC. Scientist Center for Animal Welfare, Bethesda, MD, pp. 1-4.
13. Swanson, J.C. (1994). þFarm animal well-being and intensive production systems.þ Journal of Animal Science (in press).
14. Swindle, M.M. and A.C. Smith. (1992). þRegulatory issues in experimental surgery in farm animals.þ Proceedings from a SCAW-sponsored conference, Agricultural Animals in Research, held September 6-7, 1990, Washington, DC. Scientist Center for Animal Welfare, Bethesda, MD, pp. 54-57.
15. þ1993 Report of the AVMA Panel on Euthanasia.þ (1993) Journal of the American Veterinary Medical Association, 202(2):229-249.
Selected References
a. Mench, J.A., S. Mayer, and L. Krulisch, (Eds.). (1992). Well-being of Agricultural Animals in Biomedical and Agricultural Research, Scientist Center for Animal Welfare, Bethesda, MD.
b. Mench, J.A. and Stricklin, W.R. (eds.), 1993. þAn International Conference on Farm Animal Welfare: Ethical, Technological and Sociopolitical Perspectivesþ and þScientific Perspectives.þ Journal of Agricultural and Environmental Ethics, volume 6 supplements 1 and 2, 153pp. and 116pp.
c. Food Animal Well-Being 1993 - Conference Proceedings and Deliberations, April 13-15, 1993, Indianapolis, IN. Purdue University, Office of Agricultural Research Programs, West Lafayette, IN.
by
James E. Breazile, M.A., D.V.M., Ph.D.
Professor of Veterinary Physiology and Director of
Laboratory Animal Resources
Oklahoma State University, Stillwater, OK 74078
The study of pain in laboratory animals through the past 40 years has presented us with a progressive development in our understanding of the means by which noxious stimuli elicit neural activity, and the neural pathways through which this activity reaches and terminates within the brain. At the same time, we have experienced a growth in our intellectual and philosophical consideration of pain in animals and have become more concerned about the role of pain in production of stress and discomfort in all laboratory animals (6). The inclusion of farm animals into these considerations has been a fairly recent but not unforeseen development. The explanation for delay in the inclusion of farm animals fully into the arena of research, teaching, and testing animals likely resides in the desire to isolate these practices from production practices. There are many common practices in production of animal meat and fiber that would not be considered acceptable under the current guidelines for care and use of laboratory animals. It is necessary, however, that these practices be considered on their own merit in an attempt to apply current Federal guidelines to the use of farm animals in research, teaching and testing.
It is my philosophy (and one that I think should be emphasized within our Institutional Animal Care and Use Committee (IACUC) membership) that there is a basic level of humaneness that must be applied to all species used in research, teaching and testing. I feel that this level also applies to production practices. Beyond this level, other considerations of pain perception and humane treatment are determined by the protocol applied to the animal. In the following discussion, I wish to raise some consideration of factors influencing the nature of pain sensations in animals in general, and particularly in farm animals. I hope that these considerations may be helpful in establishing the characteristics of that basic level of humaneness as it is applied to a specific research, teaching or testing protocol.
Pain has been recognized through the centuries as a word that describes a wide range of unpleasant experiences in humans (8). It has continually been recognized that it is difficult for humans to share what they have felt as a pain sensation, and to describe this experience to their own satisfaction. Realizing that the concept of pain perception is derived entirely from our human experience, and that we by necessity have extrapolated this concept to animals, leaves one with little wonder that there are difficulties in interpreting sensory and meaning phenomena within this extrapolation.
There was a time, not so long ago, when pain scientists were relatively comfortable with their understanding of the anatomic, physiologic, and behavioral aspects of pain perception in animals (3). Specific þpain pathwaysþ had been identified within the spinal cord and brain that underlie pain perception and the behavior it elicits. These were taught to veterinary medical students, to be memorized as the anatomic basis for pain perception in animals. Elaborate behavioral studies were conducted to confirm that these pathways did indeed serve as the anatomic substratum for pain perception (3). It was generally considered that wherever pain was to be evoked in an animal, anesthesia and/or analgesics would be applied. These were the days before there was a great deal of attention given to the need for extensive considerations of pain induction by the methods applied in the use of animals in research, teaching and testing. It was clearly recognized that there were anatomic substratum differences between non-primate laboratory animals and humans. These anatomic substratum differences appeared to represent degrees of neurologic differentiation. They were interpreted to represent differences in the specificity of central nervous system structures in the processing of neural information concerned with pain perception (4). There could not, however, be allowed the consideration that there might be a difference between the actual sensation experienced in humans and animals. The difficulty that these anatomic differences produced was that the only pain perception that we, as investigators, or oversight persons of IACUC responsibility, have ever experienced is our own pain. If we did not perceive pain, if this pain was not unpleasant to us, and if this pain did not induce suffering and distress in us, we would not be considering whether or not it occurs in laboratory animals.
It is necessary to assume that animals perceive pain with all its variations in intensity, sharpness, dullness, localization, or diffuseness, exactly as it is perceived by human beings. If this premise does not hold, then it is impossible to study pain in animals, because there would be no standard against which it could be measured. It was, and still must be accepted, therefore, that if a given stimulus evoked a pain sensation, emotional and escape reaction in a human, and if the application of that stimulus will evoke a similar emotional or escape reaction in an animal, that stimulus produces pain perception in the animal. It must be emphasized that it must be considered that pain perception does not differ from that perceived by a human being in the same situation.
If, however, we are to use the human as the standard, it is necessary that we clearly characterize the standard before it is applied. There are some characteristics of pain perception that are well known through everyday experience in humans that are basic to our ability to determine, quantify, and characterize pain perception in animals. I do not think that we can abandon the anthropomorphic basis of evaluating pain in animals. This is the only basis we have. I do feel, however, that it is necessary that we apply this basis from a realistic point of view. The emphasis that I would like to make is that there are some differences in our lives from those of farm animals that do make a difference in the significance of pain perception. The difference that I would like to emphasize is our anticipation of pain and the impact of this anticipation on our perception. We learn, through personal experience, or the experience of others, to anticipate pain in certain circumstances. Although animals may learn through experience, they are not generally preconditioned, to the degree experienced by humans, by the experience of others. Whether or not pain perception would normally be elicited by a given circumstance, if we think we will perceive pain, then when the stimulus is applied, we will perceive pain. Some of you may have been in the old U. S. Marine Corps (before the 60's), or may have joined a fraternity in college in which hazing was common. The experience with the blow torch, hot iron, and application of ice that you were certain burned a hole in your skin typifies this conditioning. This preconditioning often makes it difficult to evaluate pain perception in humans. A stimulus that is apparently innocuous in one human subject may induce an excruciating painful experience in another.
A good example to illustrate the effect of preconditioning and the difference it makes in suffering or distress is the comparison of a human who has undergone laparotomy, and intra-abdominal surgery, to a laboratory animal (rat, dog, cat, or farm animal) undergoing that same surgery. The human, through anticipation, anguish, and concern for the pain to come, often suffers the pain even before the act of surgery occurs. I have never experienced an animal, except in cases where multiple serial surgeries are performed, that demonstrated any degree of anticipation to surgery. After the surgery, the typical animal is on its feet, eating, running, grazing, whatever is natural for it to do. The human, on the other hand, is slow to recover, complains of much pain,and takes days to weeks to recover. This difference, not only in pain, but also the distress produced by it, is an important consideration in the evaluation of pain perception in farm animals from a strictly anthropomorphic point of view. It is clear that in these circumstances, we depart from the strict anthropomorphic interpretation of pain and distress in animals, but let the animals þspeakþ for themselves through their behavior. The sensations that are described as pain in humans, and assumed in animals (due to their anthropomorphic responses to situations in which these sensations are generated), represent a wide spectrum. We can quickly recognize that there are differences in the sensation produced by a pin prick or a burn, and one produced by neuralgia. These not only represent differences in type of sensation evoked, but also represent different stimulus modes through which the sensation is induced.
At one end of the pain sensation spectrum are the well-known protective sensations. These are usually evoked by þapplied stimuliþ such as burns, needle sticks, electric shock or other stimuli that are noxious to cells and tissues. In farm animals used in research, teaching, and testing, this þinduced painþ represents the majority of sensations referred to as pain. Induced pain initiates alarm, withdrawal, escape, or attack responses that are often accompanied by vocalization in farm animals. In humans experiencing induced pain, there is a good correlation between the afferent neural activity induced in peripheral nerve axons and the intensity of subjectively perceived pain (8). The intensity of induced pain in farm animals, that is acceptable in a research, teaching, or testing protocol, is difficult for investigators and IACUC members to discern. The presence of pain-associated reflexes, along with voluntary or þwilledþ behavior, usually serves as the basis for judging whether or not a pain perception takes place. It is generally accepted that there is a level of pain perception that is acceptable. This allows the consideration that in trained hands, needle punctures for the normal clinical collection of blood produce an acceptable level of pain or discomfort. For each protocol, that goes beyond this level, the investigator and members of IACUC must use their judgement concerning the intensity of pain induced.
At the other end of the spectrum are non-protective pain sensation syndromes produced by organic or patho-physiological mechanisms. This type of pain sensation is generally the consequence of naturally occurring, or experimentally induced peripheral or central neuropathies (1). It can reasonably be referred to, therefore, as þneuropathicþ pain. It is the sort of pain that is experienced in neuralgia, so familiar to humans (11). Such neuralgias may be induced in animals by disease processes, or by experimental processes (7). Polyneuropathies, diabetes, toxin or viral induced, can result in the production of intense pain perception in humans, and must be considered to do so in farm animals as well. It is necessary that investigators and IACUC members be cognizant of this type of pain induction, and its significance in producing distress that may interfere with the well-being of the animal and the outcome of the research (5). A portion of the campus educational program provided to animal research personnel should include discussion of the possibility of neuropathic pain induced by specific types of experimental protocols.
Between the two extremes of þinducedþ pain and þneuropathicþ pain is pain that is associated with inflammation. This þinflammatoryþ pain is distinctly different from the two extremes, in that it is induced by mechanisms of tissue response to injury, rather than an external stimulus that would be regularly considered to induce pain perception (9, 10). The pain associated with inflammation usually requires some additional stimulus for initiation, but this stimulus need not be noxious (which implies damage, or potential damage to tissues). Even the slightest movement or lightest tactile stimulation may initiate pain perception in the presence of inflammation. Recognition and prevention of pain-induced distress in farm animals, as in other species, is aided by a knowledge of the neuro-physiological mechanisms underlying pain sensation. This knowledge is particularly necessary to those directly responsible for use of animals in research, teaching, or testing, so that they may discern whether or not, toxins, microbiological agents or drugs used in their protocols may mask or prevent a response to pain. These animals may demonstrate a number of distress responses that are not clearly discerned as due to pain induction.
Although it is necessary that the judgement of the distress-producing capability of pain sensation be anthropomorphically based, those who use farm animals as laboratory animals and IACUC members must also be aware of protocols that are likely to induce pain in circumstances in which it would not ordinarily be expected in humans. It is equally as important that those judging research protocols on the basis of animal responses be aware of normal animal behavior. In most farm animals, unsocialized with humans, even the slightest stimulus, whether it be noxious or not, may induce vocalization, alarm, withdrawal, escape, or attack responses that could easily be ascertained as induced by pain or discomfort. Recognition of pain perception in farm animals, as in other species, requires a thorough knowledge of the normal behavior of that species. Chronic pain perception or chronic distress from any cause generally results in decreased appetite, motility, milk, egg or meat production in farm animals. There is no list of signs that infallibly indicate that pain is being perceived in any given farm species. There are some characteristics of individual animals within a farm species, or often within a species as a whole, that are helpful in making this determination and of estimating the degree of discomfort that is present. If there is any doubt, however, concerning whether or not an animal is experiencing undue or unacceptable levels of pain, one should consult a veterinarian or animal husbandryman who is familiar with the species in question. Usually animal care personnel are the first to know when an animal is distressed by disease or a pain-inducing process. They should be an integral part of this evaluation. The author may be contacted by phone at 405-744-8089, or by FAX at 405-744-6743.
References
1. Bennett, G. J. (1990). þExperimental models of painful peripheral neuropathies.þ News in Physiol. Sci. 5:128-133.
2. Breazile, James E. and Kitchell, R. L. (1968). þA study of fiber systems within the spinal cord of the domestic pig that subserve pain responses.þ J. Comp. Neurol. 133:373-382.
3. Breazile, James E. and Kitchell, R. L., (1969). þPain perception in animals.þ Fed. Proc. 28:1379-1382.
4. Breazile, James E., (1971). Textbook of Veterinary Physiology, Lea and Febiger, Philadelphia
5. Breazile, James E., (1987). þPhysiologic basis and consequences of distress in animals.þ J.A.V.M.A. 191: 1212-1215.
6. Breazile, James E., (1988). þThe physiology of stress and its relationship to mechanisms of disease and therapeutics,þ in Howard, J. L. (ed.), Stress and Disease in Cattle,The Veterinary Clinics of North America, Food Animal Practice 4 (3): 441-480.
7. Campbell, J. N., Raja, S. N., Meyer, R. A. and Mackinnon, S. E., (1988). þMyelinated afferents signal the hyperalgesia associated with nerve injury.þ Pain 32:89-94.
8. Cervero, F. and Laird, J. M. A., (1991)." One pain of many pains? A new look at pain mechanisms." News in Physiol. Sci. 6:268-273.
9. Hylden, J. L., Nahin, R. L., Traub, R. J. and Dubner, R., (1989). þExpansion of receptive fields of spinal lamina I projection neurons in rats with unilateral adjuvant-induced inflammation: the contribution of dorsal horn mechanisms.þ Pain 37:229-243.
10. Meyer, R. A., Campbell, J.N. and Raja, S. N., (1985). þPeripheral neural mechanisms of cutaneous hyperalgesia.þ Advances in Pain Research and Therapy 9:53-71.
11. Sato, J. and Perl, E. R., (1991). þAdrenergic excitation of cutaneous pain receptors induced by peripheral nerve injury.þ Science, Wash. D. C. 251:1608-1610.
by
Richard V. Shawley, DVM, MS, DACVA
Department of Medicine & Surgery, College of Veterinary
Medicine
Oklahoma State University, Stillwater, Oklahoma 74078
This discussion reviews some of the common anesthesia problems when
dealing with the large animal species used in research. This includes
cattle, sheep, goats, and swine.
Neonatal Anesthesia
Frequently, research projects require general anesthesia for neonates of farm animal species. The neonate has several significant physiological differences from the adult animal that affect anesthesia. These differences include:
The blood brain barrier is poorly developed because the junctions between endothelial cells and the choroid plexus are wider than in the older animal. As a result, induction of anesthesia may be quicker and requires less drug in the neonate than in the adult animal(1).
Hypothermia. Neonates have a greater body surface:body weight ratio (2). As a result, they lose heat more rapidly than adult animals. With hypothermia, drug metabolism is retarded and the neonate may be slow to recover, especially from injectable anesthetics that depend primarily on metabolism for complete recovery.
Hypoproteinemia. Plasma protein levels, particularly albumin levels, are lower in the neonate than in the adult. This means that neonates are more likely to develop pulmonary edema from intravenous fluid therapy (3). Also many anesthetic drugs are protein bound. Therefore, smaller doses of anesthetics may be required in neonates (particularly barbiturates) than in adults. It is the nonbound anesthetic that crosses the blood brain barrier (4).
Low body fat content. Fat represents a storage depot for anesthetic drugs. In the case of neonates, the lack of body fat means that redistribution of anesthetic drugs will be delayed and recovery will be slow due to prolonged plasma levels (5).
Hepatic function and hypoglycemia. In general, the clearance of
drugs by the liver is less than in the adult. Microsomal enzyme
development is incomplete, resulting in the delayed clearance of drugs
(6). Neonates also have poor glycogen stores; consequently,
hypoglycemia can readily occur in the stressed neonate (2). @SUBHEAD =
Anesthetic Techniques For Neonates
Ruminant Anesthesia Problems
Regurgitation
Ruminants are prone to regurgitate and aspirate the rumen contents with
anesthesia. Regurgitation is a result of several factors. Anesthetics
relax the pharyngeal-esophageal sphincter and the reticulo- esophageal
sphincter. Anesthetics also depress the swallowing reflex, thereby
reducing the animal's ability to protect its airway from any
regurgitated material. When the ruminant becomes recumbent, pressure
is applied to the rumen. This increase in rumen pressure with
sphincter relaxation results in regurgitation. To reduce the incidence
of regurgitation and aspiration, fasting prior to elective anesthetic
procedures is indicated. The guidelines for fasting prior to
anesthesia are as follows:
Adult cattle: withhold food for 24-36 hours and water for 12-24
hours prior to anesthesia
Small ruminants: withhold food for 12-24 hours and water for 0-12
hours prior to anesthesia
Ruminants less than 1 month of age are not fasted prior to
anesthesia.
In addition to fasting, intubation is highly recommended. Use of a
properly inflated, cuffed endotracheal tube will protect the lower
airways from regurgitation.
Bloat
Anesthesia eliminates the ability of the animal to eructate. Also
during anesthesia, rumen motility is reduced. These two factors lead
to gas formation that, if excessive, will result in pressure on the
diaphragm and a decrease in lung volume. Ventilation perfusion (V/Q)
mismatching occurs during anesthesia in large animals because of
gravity and blood flow changes due to decreased cardiac output (9).
V/Q mismatching is accentuated by bloat and results in a further
decrease in oxygenation. Proper fasting as discussed above will
diminish the incidence and severity of bloat during anesthesia.
Injury
Induction and recovery injuries such as fractures can occur even with
the best of facilities but they should never occur because of poor
facilities. Adequate restraint and trained personnel are essential for
successful inductions of general anesthesia of large animals. Nerve
paralysis is usually due to prolonged anesthesia, with inadequate
padding or positioning. Post-operative myositis may also be due to
prolonged down time with inadequate padding (10). However, myositis can
be due to poor perfusion of muscle during anesthesia. This can be
attributed to failure to maintain adequate cardiac output and
sufficient blood pressure for adequate muscle perfusion.
Preanesthetic Sedatives
Xylazine
Xylazine, an alpha2 adrenergic agonist, can be used as a sedative in
low dosage. Ruminants are very sensitive to xylazine. The dose in
ruminants is approximately one-tenth that used in the horse. However,
xylazine is not approved for food-producing animals. The following
dosage guidelines are for healthy adult animals not receiving any other
preanesthetic drugs.
Detomidine
Detomidine is an alpha2 adrenergic agonist that has similar
characteristics to xylazine. It is, however, much more potent. It is
approved for use in the horse but not in food-producing animals. The
suggested dosage for cattle is 20-80 ug/Kg IM (11).
Side Effects of Alpha2 Adrenergic Agonists
The most common life-threatening side effect of alpha2 adrenergic
agonists in ruminants is bloat.
Rarely is this a significant problem if the animal has been properly
fasted. Treatment, in addition to sternal positioning and stomach tube
passage, could include the use of an alpha2 adrenergic antagonist.
Excessive salivation frequently occurs following the use of alpha2
adrenergic agonists. The use of atropine is not very effective and of
very short duration. Treatment of excessive salivation consists of
preventing its tracheal aspiration by keeping the nose and mouth of the
animal lower than the pharynx. Bradycardia occurs with alpha2
adrenergic agonists. Treatment with atropine is rarely necessary but
will correct the bradycardia. For cattle exhibiting bradycardia due to
alpha2 agonists, the initial intravenous dose of atropine is
approximately 0.02 mg/Kg. If no response is seen the dose should be
repeated.
Alpha2 Adrenergic Antagonists
These drugs are used to reverse the effects of alpha2 adrenergic
agonists. Reversal is usually rapid and complete, however, results in
ruminants with yohimbine have been variable (13) while tolazoline and
yohimbine have produced variable results in horses (14). Idazoxan and
atipamezole are very specific alpha2 adrenergic antagonists but are not
readily available at present.
Anesthetic Combinations For Sheep, Goats, And Cattle
The following methods of producing anesthesia are for procedures
usually less than 45 minutes or for induction/intubation of gas
anesthesia. Since most anesthetics are not approved for use in
food-producing animals, these recommendations are for animals not
entering the food chain.
Sheep And Goats
Xylazine/Ketamine
In this combination the two drugs are given according to the dose
listed:
The amount of gas anesthesia during the first 15-20 minutes of the
procedure would be minimal.
As the xylazine: ketamine combination is eliminated, gas concentrations
will need to be increased.
Cattle
Thiopental/Gurafenesin
This combination is a very reliable method of producing general
anesthesia with good muscle relaxation. Guiafenesin is a
central-acting muscle relaxant that can be purchased in powder form or
solution. The barbiturate, thiopental, is added to the guiafenesin
solution. The dosage for healthy cattle is as follows:
Thiopental 6.6 mg/Kg IV (5 Gm max dose)
Guiafenesin is usually prepared in a 5 or 10 percent solution with
sterile water, saline or 5% dextrose. If the 5 percent solution is
used, a large bore catheter (10-12 ga.) is required for rapid
administration to provide a smooth induction of adult cattle.
Anesthetic Methods for Swine
Adult swine can be very difficult anesthetic patients. Both
intravenous and intramuscular routes have been used for anesthetic
procedures of short duration or for induction of gas anesthesia.
Intravenous thiopental or thamylal at a dose of 9-11 mg/Kg is used for
procedures of 5 to 10 minutes duration and for tracheal intubation. A
combination of xylazine/Telazolþ (teletamine-zolazepam) can be used via
the intramuscular route. The dosage is xylazine (1.1 mg/Kg) and
Telazol (3 mg/Kg) given intramuscularly.
Inhalation Anesthesia
As research surgical procedures have become more sophisticated, the
need for quality anesthesia of long duration has developed and the use
of inhalation anesthesia has increased. Some of the reasons why gas
anesthesia is superior to injectable techniques without respiratory
support include the following:
Provides a patent airway. Gas anesthesia usually utilizes an
endotracheal tube. This ensures an open airway and saves valuable time
in an emergency when respiratory control is required.
Improves oxygenation. Because oxygen is used as the carrier gas for
inhalant anesthetics, arterial oxygen tension is much higher than in
animals breathing air. This is of particular importance to large
animals because of low oxygen tension during anesthesia.
Facilitates control of ventilation. By using positive pressure
ventilation, arterial carbon dioxide levels can be maintained near
normal preventing cardiac arrhythmias that may develop with a
respiratory acidemia.
Control of the depth of anesthesia. During surgery the analgesic
requirements may vary. Changes in the depth of anesthesia can be
quickly achieved. If emergencies arise, the administration of
inhalants can be stopped immediately and the system flushed with oxygen
to hasten recovery.
Smooth and rapid recovery. Because almost all inhalant anesthetic
is eliminated via the respiratory system, recovery is relatively quick
and with minimal excitement. Injectable anesthetic techniques,
however, depend upon metabolism for elimination of the agent.
@SUBSUBHEAD = Inhalation Anesthetic Agents
Halothane
Halothane has a MAC (minimum alveolar concentration) of approximately
0.9 percent for most species. The MAC value is a measure of a gas
anesthetic's potency. By knowing the MAC value one can estimate the
maintenance level of anesthetic (vaporizer setting) required for
surgical anesthesia. The vaporizer setting is in the range of 1.5-2
times the MAC value. For halothane the vaporizer setting is
approximately 1.5-2 percent. The vaporizer setting may be reduced by
preanesthetic and induction agents. Halothane can be used for mask
inductions of neonates since it produces a relatively quick induction
with minimal excitement. The effect of halothane on the cardiovascular
system has been studied extensively (15,16). Halothane is a very useful
and relatively inexpensive inhalant anesthetic and will continue to be
a widely used agent in all species.
Isoflurane
Isoflurane has been available since the early 1980's. The advantages
versus halothane include a quicker induction and recovery with less
cardiovascular depression. The incidence of dysrhythmias during
isoflurane anesthesia is substantially reduced when compared to other
agents (15,16). Isoflurane is relatively expensive to use when
compared to halothane. Isoflurane has a MAC value of approximately 1.3
percent This translates to a maintenance level (vaporizer setting) of
2-3 percent. Malignant hyperthermia, previously reported in swine
exposed to halothane, may also occur with exposure to isoflurane (17).
Epidural Alpha2 Adrenergic Agonists and Opioids
Recently there has been considerable interest in the use of epidural
anesthesia both for providing surgical anesthesia and for
post-operative analgesia. Xylazine has been the primary drug utilized
for surgical anesthesia. Xylazine has been administered epidurally,
primarily at the coccygeal1 - coccygeal2 space, for both horses (18)
and cattle (19). The onset of anesthesia is slower than that seen with
lidocaine but is longer in duration. Also in the bovine, the analgesia
advances forward to the flank area with the patient remaining in the
standing position. Opioids have primarily been used for post-operative
analgesia. Epidural morphine in the dog has been used to provide
post-operative analgesia lasting up to 24 hours. The amount required
is much less than that given intramuscularly for analgesia and does not
interfere with motor function or produce depression of the
cardiovascular system (20). The use of epidural opioids in food animal
species requires further investigation before any recommendations can
be made. References
1. Saunders, N.R. (1977). þThe blood brain barrier in the foetal and
newborn lamb.þ Annales de Recherches Veterinaires 8:384-395.
2. Steward, D.J. (1992). þAnesthetic Considerations for Neonates and
Grownup 'Preemies'.þ1992 ASA Refresher Course Lectures 146:4.
3. Robinson, N.E. (1992). þThe Respiratory System.þ In Equine
Anesthesia Monitoring and Emergency Care, W. W. Muir III and J.A.E.
Hubbell, (eds.), St. Louis, MO, Mosby Year Book 1992, 2:20.
4. Muir, W.W. III. (1992). þIntravenous Anesthetics and Anesthetic
Techniques in Horses.þ In Equine Anesthesia Monitoring and Emergency
Care, W. W. Muir III and J.A.E. Hubbell, (eds.), St. Louis, MO, Mosby
Year Book 1992, 12:286.
5. Mihaly, G.W., et al. (1978) þThe pharmakinetics and metabolism of
the anilide local anesthetics in neonates.þ European Journal of
Clinical Pharmacology 13:143-152.
6. Baggot, J.D., and Short, C.R. (1984). þDrug disposition in the
neonatal animal, with particular reference to the foal.þ Equine
Veterinary Journal 16:364-367.
7. Webb, A.I. (1984) þNasal intubation in the foal.þ Journal of the
American Veterinary Medical Association 185:48-51.
8. Shawley, R.V. Personal observation.
9. Hall, L.W., Gillespie. J.R., and Tyler, W.S. (1968).
þAlveolar-arterial oxygen tension differences in anesthetized horses.þ
British Journal of Anesthesiology 40:560-568.
10. Lindsay, W.A., et al. (1985). þEffect of protective padding on
forelimb intracompartmental muscle pressures in anesthetized horses.þ
American Journal of Veterinary Research 46(3):688-691.
11. Alitalo, I. (1985). þClinical experience with domosedan in horses
and cattle.þ In Proceedings of the Domesedon Symposium, Tucker,
Finland, 1985, p.17.
12. Gross, M.E., and Tranquilli, W.J. (1989) þUse of alpha-2
adrenergic receptor antagonists.þ Journal of the American Veterinary
Medical Association 195:378-381.
13. Thompson, J.R., Kersting, K.W., and Hsu, W.H. (1991).
þAntagonistic effect of atipamezole on xylazine-induced sedation,
bradycardia and ruminal atony of calves.þ American Journal of
Veterinary Research 52: 1265-1268.
14. Greene, S.A., et al. (1987). þEffect of yohimbine on xylazine
induced hypoinsulinemia and hyperglycemia in mares.þ American Journal
of Veterinary Research 48:676-678.
15. Joas, T.A., and Stevens, W.C. (1971). þComparison of the
arrhythmia doses of epinephrine during forane, halothane and floroxene
anesthesia in dogs.þ Anesthesiology 35:48-53.
16. Johnston, R.R., Eger, E.I. II, and Wilson, C. (1976). þA
comparative interaction of epinephrine with enflurane, isoflurane, and
halothane in man.þ Anesthesia and Analgesia 55:709-712.
17. McGrath, C.J., et al. (1981). þMalignant hyperthermia triggering
liability of selected inhalant anesthetics in swine.þ American Journal
of Veterinary Research 42:604-607.
18. LeBlanc, P.H., et al. (1988). þEpidural injection of xylazine for
perineal analgesia in horses.þ Journal of the American Veterinary
Medical Association 193:1405-1408.
19. Zaugg, J.L. and Mussbaum, M. (1990). þEpidural xylazine: a new
option for surgical analgesia of the bovine abdomen and udder.þ
Veterinary Medicine 85:1043-1046.
20. Bonath, K.H.and Saleh, A.J. (1985). þLong term pain treatment in
the dog by peridural morphines.þ In Proceedings of the 2nd
International Veterinary Anesthesiology Symposium, Santa Barbara, CA,
Veterinary Practice Publishing Co., p.161.
by
Mildred M. Randolph, DVM
Introduction
Farm animals are being used with increased frequency in research
facilities. As biomedical researchers and investigators, we must
recognize and accommodate their unique husbandry needs. These farm
animals should be housed in areas designed specifically for them.
Unfortunately, it may not be advisable to put pigs or goats in a
facility's largest dog pens. These animals will probably be less
domesticated than the typical research cat or dog, and the þhuman
contactþ factor may not be as essential to their well-being. However,
their needs should be considered as we prepare to house them for
extended periods of time. The environment that the animals encounter,
beginning with their initial entrance into the facility, can contribute
to a smooth operative and post-operative period. They should be housed
in the least stressful environment possible. Food and water intake, as
well as social behavior, should be monitored as an indication of
overall well-being. More research is needed to develop analgesics that
address some of the challenges these animals present during the
post-operative period. Farm animals used in biomedical research would
benefit from analgesics with longer duration times, increased routes of
administration and shelf-life, reduced addictive potential, and wider
margins of safety. As we increase our usage of farm animals in invasive
surgical procedures, we are obligated to circumvent post-operative pain
and other stressors resulting from our experimentation.
Pain Perception and Analgesics
As ethology research increases, hopefully our knowledge of the
expression of animal pain will increase proportionally. Being familiar
with the normal behavior is imperative in assessing abnormal activity
and temperament in farm animals. Parameters for þnormalþ behavior vary
not only from one species to another, but also from one individual
animal to another. It may prove to be a very expensive endeavor, both
in time and money, to engage in any research protocol without first
thoroughly familiarizing yourself with the normal activity of your
animal model. Close communication between animal caretakers and the
researchers works toward the best interest of the animal in the
post-operative period. An astute caretaker's knowledge of the normal
behavior for that particular age, sex, species, and individual is
crucial in determining when animals are experiencing unacceptable
levels of pain. One of the best clinical assessments in distinguishing
normal from abnormal behavior is the feeding pattern. Many species of
farm animals experiencing pain and distress do not eat normally.
However, this does not mean that any animal that seeks food
post-operatively does not need pain management. When animals are housed
in a group, it would be helpful to remove the post-surgical cases for
daily weight checks. A reduction of food intake will also be reflected
in fecal and urine output. Too, the animal that separates itself from
the rest of the animals with which it is housed may need additional
attention. Other signs of discomfort may be an alteration in an
animal's gait or a constant changing of position. Also, some species of
farm animals (especially goats) will increase their vocalizations when
in pain. Pigs are notorious for becoming either aggressive or seeking
solitude when they are uncomfortable. Sheep seem to be unique in their
ability to tolerate high levels of pain with only minor changes in
their normal behavior. The need for researchers to learn the normal
behavior of their particular animal model is easily understood. There
is a general consensus that animals perceive pain. However, as
researchers we have been slow to respond to this awareness, especially
when farm animals are used in biomedical research. As farm animals
become increasingly popular in research, it is not only appropriate,
but also an obligation for researchers to familiarize themselves with
both the obvious and the more subtle signs of pain and discomfort in
these large animal species. We should assume that any procedure that
would cause pain in humans will also cause comparable discomfort in
farm animals. Invasive procedures causing tissue injury should be
expected to result in varying degrees of post-operative pain. When this
is anticipated, a plan should be in force to administer appropriate
tranquilizers and analgesics post-operatively. The goal is not directed
toward giving relief so much as it is toward circumventing pain by
designing a protocol which includes adequate analgesics given prior to
the onset of severe discomfort. As we decide on appropriate analgesics,
the surgical procedure must be considered. Certain surgical sites are
likely to present a greater pain management challenge than others.
Extensive surgical procedures involving the areas of the cervical
spine, sternal approaches to the thorax, the head, eye, ear, mouth,
rectal area and bones will all generally result in moderate to high
degrees of pain post-operatively. Since this sensitivity has been
documented in other species, we should investigate which analgesics
would be most appropriate for those experiments requiring surgery in
these areas. The proper analgesic selection has much to do with the
particular animal model that is being used. Some research has been
performed that compares differences among common domestic farm animals
and their ability to utilize various analgesics. There are species
differences that influence the deposition of analgesic drugs. These
differences, many of which are anatomical, will affect the selection
and route of administration for various analgesic drugs. The digestive
tracts of various domestic species reflect a difference in the drug
deposition. For example, swine have simple stomachs with a spiral
colon. It has been reported that this feature does not greatly
influence drug deposition. Yet horses, being herbivorous, rarely have
an empty stomach, and there follows a reduced opportunity for the drug
to be absorbed. Cows and other ruminants have large acidic environments
in their digestive tracts from which many drugs are not easily
absorbed. Also, many drugs are destroyed by the enzymes produced by the
ruminal flora. These factors should be remembered as researchers decide
on their armament of pain medicines.
Specific Analgesics
Opioid agonists (morphine, meperidine, oxymorphone, and fentanyl) and
agonist-antagonists (pentazocine, butorphanol, nalbuphine, and
buprenorphine) are two groups of effective analgesics. Opioid agonists
probably have the best reputation for providing potent analgesia. When
administered in analgesic dosages and given intramuscularly or
subcutaneously, they are unlikely to cause detrimental side effects.
Unfortunately, in farm animals the use of morphine and other opiates is
known to cause excitement. Therefore, when opiates are used for
analgesic purposes in farm animals, they are used in conjunction with
other drugs. Analgesics work best when their use is initiated to
prevent post-operative pain. Low doses of analgesics given prior to
full recovery mean that fewer analgesics will be necessary and that any
pain will be more readily managed. Opioid agonist-antagonists have some
advantages over opioid agonists. They have limited abuse potential and
are not strictly controlled. They do not produce the profound analgesic
response that characterize the opiates; however, they can be very
helpful in pain management. These drugs also have a þceiling effect,þ
and depending on the given situation, this may or may not be an
advantage. Increasing the dosage of butorphanol, for example, above the
optimal dose does not increase the analgesic effects or incite
respiratory depression. The advantage of this is that the respiratory
system is spared from further depression. However, the analgesic
effects are also limited by this same þceiling. þ Another advantage of
these opioid-antagonists is that they can be used to antagonize opioid
agonists. Buprenorphine appears to be one of the longer acting
agonist-antagonists. It has the advantage of being able to be
administered by various routes (IV, IM, SC, and IP). However, the most
encouraging aspect about this drug is that dose intervals are up to 12
hours in pigs, and 4-6 hours in sheep and goats. Nonsteroidal
anti-inflammatory drugs, although commonly overlooked, can be very
helpful in the management and treatment of post-operative pain. Many of
these drugs (aspirin, ibuprofen, and phenylbutazone) are excellent
anti-inflammatory, antipyretic and analgesic agents. The disadvantage
is that they modify the release of arachidonic acid, and this may
interfere with experimental studies. They are not the potent analgesics
that the opiates are. Meperidine, a commonly used opioid agonist, has
been found to have an undeserving reputation as an analgesic drug in
farm animals. The literature is now showing that this drug has a half
life of less than 1 hour, making its use in farm animals less than
practical. Likewise, pentazocine has been shown to have very rapid
elimination from farm animal species.
Suggested Practical Analgesics for Farm Animals Used in Biomedical
Sciences
The Post-operative Period
The recovery period should be viewed as the final stage in the surgical
procedure. Some investigators and their staff have underestimated the
importance of this stage of the surgical endeavor. There can be no
successful surgery with an unsuccessful recovery. Often, mistakes made
during the surgical procedure come back to haunt the research staff
during the recovery stage. For example, large pigs that were given
excessive doses of a barbiturate experience a protracted recovery
period.
Post-operative care should be assigned to a particular person on the
research team. The recovery of animals used in surgical experimentation
should take place in a specific area designed to meet the special needs
of animals during the post-operative period. The post-operative
environment should be characterized by a room equipped with subdued
lighting. The ambient temperature should be near 27-30 oC for adult
animals and 35-37 oC for young animals. It is important to monitor the
body temperature as well as the environmental temperature. As the
animal recovers, it will regain the ability to maintain its own
temperature and diminish the need for heating pads, etc. Care must then
be taken to ensure that the animal does not become over-heated.
The maintenance of a patent airway is important in any recovering
animal. An endotracheal tube should remain in position until the
animal's swallowing reflex has returned. This dimension has increased
importance in certain species, such as the pigþan animal that has a
tendency to vomit. Small ruminants (sheep and goats) should be placed
in a sternal position. This position tends to reduce the incidence of
overdistention of the rumen and the aspiration of rumenal contents.
Repositioning to avoid hypostatic pneumonia is important if the animals
are still recovering after 3 to 4 hours.
Animals recovering from surgical procedures should do so in a warm, dry
environment. Farm animals should be allowed to recover on fresh
bedding, such as straw. Providing a thick, non-skid surface will reduce
the incidence of pressure sores and injury as the animal attempts to
stand and ambulate.
One of the major problems in providing the ideal recovery room for farm
animals is the recurring problem of adequate space. A large-size room
is absolutely necessary for large animals as they recover from surgery.
This can become a major problem in situations where up to 25 surgeries
may be performed on a group of experimental goats or sheep in a single
day. These animals need to be placed several feet apart while they
recover. Incidents have been recounted wherein adequate space was not
provided, and sheep were stacked on top of one another during recovery
from general anesthesia. An unfortunate scenario developed from one
such situationþone of the sheep on the bottom died from suffocation,
while many of the others had to be treated for rumenal tympany.
Optimal recovery conditions may be even more important for farm animals
used in research than they are for rodents, dogs or cats. The farm
animals commonly used in biomedical research (sheep, goats and pigs)
are less likely to be amenable to the routine handling required in the
case of any post-operative complications. It is in the best interest of
the investigator to reduce the need for restraining these animals
unless it becomes absolutely necessary. Therefore, maintaining a clean
surgical incision and supplying clean bedding may reduce the incidence
of having to treat post-operatively. As these animals recover, they are
also more likely to be fearful and nervous. A non-skid floor surface in
an area with reduced noise and lighting will all encourage a smooth
recovery.
A time-intervaled, record-keeping system should be operational in the
recovery area. At specific intervals, the heart rate, respiratory rate,
temperature, and acid-base status should be monitored on each
recovering animal. Such intermittent recording of various vital signs
requires a commitment on behalf of the researcher and the nursing
staff, helping to magnify the importance of the recovery stage to those
individuals keeping records.
Summary
As researchers plan surgical procedures, post-operative analgesics
should be an important consideration. Analgesics must be selected based
upon the specific farm animal involved in the experiment. It should be
assumed that any invasive surgery, and perhaps some minor surgeries,
will require post-operative pain medication. These drugs should be
given prior to the onset and clinical manifestation of severe pain. The
best attitude to adopt in order to avoid unexpected events in the
recovery room is one of prevention. By anticipating and preparing for
worst-case scenarios, recovery room technicians are forced to mentally
rehearse actions to be taken in the case of an emergency. The recovery
of farm animals may present a distinct problem because of the large
amount of space required for a safe recovery. As researchers routinely
make provisions for monitoring animals during the post-operative
period, failure to make arrangements for the essential post-operative
needs will become increasingly unacceptable. No environment in a
research facility can ever be totally free of factors that stress the
research animals. However, it is our moral and scientific obligation to
reduce, for the entire duration of their stay, the chronic and extreme
stressors placed upon the animals entrusted to our care.
References
Flecknell, P. A. (1987). Laboratory Animals Anesthesia. Academic Press,
Inc., San Diego, CA.
Haskins, Steve C. and Klide, Alan M. and guest editors. (March 1992).
The Veterinary Clinics of North America. W. B. Saunders, Philadelphia,
PA.
National Research Council. (1992). Recognition and Alleviation of Pain
and Distress in Laboratory Animals. National Academy Press, Washington,
DC.
Short, C.E. and Van Poznak, A. (1992). Animal Pain. Churchill
Livingstone, New York, NY.
Future Development of USDA Standards for Farm Animals
Under the Authorities of the Animal Welfare Act
by
Bonnie Buntain, DVM, MS
Historical Background
The Animal Welfare Act (AWA) (7 U.S.C. 2131 et seq.), enacted in 1966
and amended in 1970, 1976, 1985, and 1990, authorizes the Secretary of
Agriculture to promulgate standards and other requirements governing
the humane handling, housing, care, treatment and transportation of
certain animals by dealers, research facilities, exhibitors, carriers,
and intermediate handlers. Regulations established under the Act are
contained in Title 9, Code of Federal Regulations, Parts 1, 2, 3, and
4. From the time the Act was amended in 1970 (Public Law 91-579), the
definition of the term þanimalþ has included þany live or dead dog,
cat, monkey (nonhuman primate mammal), guinea pig, hamster, rabbit, or
such other warmblooded animal, as the Secretary may determine is being
used, or is intended for use, for research, testing, experimentation,
or exhibition purposes, or as a pet. . ." (7 U.S.C. 2132 (g)).
The following animals are excluded from the term and therefore are not
covered by the Act: þ. . . horses not used for research purposes and
other farm animals, such as, but not limited to livestock or poultry,
used or intended for use as food or fiber, or livestock or poultry used
or intended for improving animal nutrition, breeding, management, or
production efficiency, or for improving the quality of food or fiber .
. ." (7 U.S.C. 2131 (g)).
The U.S. Department of Agriculture (USDA) is authorized by the Act to
regulate horses when used for biomedical or other nonagricultural
research and is authorized to regulate other farm animals when the
animals are used for biomedical or other nonagricultural research,
nonagricultural exhibition, or as pets. Prior to 1990, USDA had not
generally enforced the AWA regulations with respect to horses and other
farm animals. However, with increasing use of horses and other farm
animals in biomedical research and nonagricultural exhibition and
comments and inquiries from members of the public and regulated
industries, USDA reevaluated its policy regarding the need to extend
enforcement of regulations to include these animals. In April 1990,
USDA published in the Federal Register its intent to begin regulating,
under the AWA, farm animals used for nonagricultural (nonproduction)
research and exhibition and wholesale purposes; and horses used in
nonagricultural research. Nonagricultural practices would include, but
are not limited to, biomedical research to advance animal or human
health; exhibition of farm animals under specified settings; or
breeding of farm animals for exhibition or research purposes. Comments
regarding future regulations were simultaneously solicited from the
public. In order to better provide humane standards to farm animals
under the Act's authorities and to respond to comments expressed by
various interest groups, regulated entities, and the general public,
USDA believes more specific guidelines are appropriate.
Current Standards
Currently, the Animal and Plant Health Inspection Service (APHIS) is
using the existing requirements contained in Part 3, Subpart F, of the
AWA regulations. These regulations are applied to farm animals as
defined in the Act for nonagricultural research and exhibition, and for
wholesale purposes, as well as horses used for nonagricultural
research. We have become increasingly aware of the need to provide
species-specific standards, when applicable, for farm animals in order
to best address their individual needs to ensure proper humane care,
treatment, housing, and transportation. Therefore, USDA is resuming
the process of gathering information before developing regulations. We
emphasize that farm animals used in production agriculture are not
currently covered under the AWA nor is USDA seeking to bring the use of
animals in production agriculture under its purview. Specific
standards to enhance uniform enforcement of the Animal Welfare Act are
currently under consideration and development. An open exchange of
ideas is needed today to develop fair, effective and scientifically
sound regulatory standards, where applicable.
Open Public Forums and Federal Interagency Meetings
In an effort to canvass the concerned public for recommendations on the
housing, care, handling, and unique practices applied to
nonagricultural use of farm animals, the USDA sponsored a meeting on
September 28-29, 1993, in Oklahoma City, Oklahoma. Approximately 125
people attended this meetingþthe general public, research and
exhibition industries, animal science and veterinary medical
organizations, animal protection groups, and leaders from academic
institutions and government agencies. Specific workshops were held to
address: agricultural exemptions, agricultural vs. nonagricultural
environment, well-being of farm animals, and special considerations for
major operative procedures. The following summarizes some
recommendations:
Standards should include use of the Guide for the Care and Use of
Agricultural Animals in Agriculture Research and Teaching, the NIH
Guide for the Care and Use of Laboratory Animals, nationally recognized
production and research facilities' standards, and international farm
animal regulations.
There should be minimum performance and design standards for farm
animal well-being.
The Institutional Animal Care and Use Committee (IACUC) and USDA
should provide oversight for the use of all farm animals in research,
teaching, and testing.
Within the intent and provisions of the AWA regulations, the IACUC
should decide when to grant exemptions from enforcement of AWA
provisions in farm settings regardless of the intent of the research,
teaching, or testing.
Major operative procedures and post-operative recovery periods
should be covered by the AWA standards (and therefore are not exempt,
or referred to as þnonexemptþ).
Biomedical research where animals are used as models should also be
nonexempt.
There should be uniformity in the enforcement of the standards, yet
flexibility in the process.
Multi-disciplinary team approach by IACUCs and USDA inspectors is
needed to enhance compliance and enforcement of the standards.
Specific species standards should be developed.
Research personnel, IACUC members, and USDA inspectors should
receive training and be educated in farm animal practices.
AWIC should be a center for all farm animal welfare information.
Endoscopic surgery for research and teaching (non-diagnostic)
should be done in USDA registered facilities.
Farm animals used in research, teaching and testing should not
enter the food chain unless approved by the Food and Drug
Administration.
Animal husbandry and agriculture-related procedures (tail docking,
castration, dehorning, etc.) should be exempt from AWA standards unless
they are part of the scientific research protocol.
Production agriculture farms supplying animals for research should
be exempt from being USDA registered facilities.
No animal should be used in more than one major operative
procedure.
Regulations for the transportation of farm animals should be
developed.
All surgical exercises should meet professional veterinary
standards.
Those farm animal facilities which are certified by the American
Association for the Accreditation of Laboratory Animal Care should be
considered for fewer USDA inspections.
In December 1993, the USDA held a meeting with Federal representatives
requesting input for the development of these standards. Some of the
issues and topics discussed included the following:
The Final Steps
USDA staff will prepare a regulatory work plan and seek administrative
acceptance of the plan. Next, a draft of farm animal regulations will
be developed for governmental clearance. The proposed regulations will
be published in the Federal Register and a period of public comment
will be allowed. Comments will be reviewed and considered, and
regulations will be modified, where appropriate, before implementing
the final rule of the regulations. Society's changing values have
influenced the global importance of animal well-being, including the
adoption of international farm animal guidelines and regulations under
specific conditions. This is clearly evidenced by recent international
requirements in the European Community, Canada, and New Zealand. It is
important that USDA continue its information-gathering process to
assist in the development of well-balanced regulations which will
ensure and enhance the humane care and treatment of animals.
BOOK REVIEW
PRINCIPLES OF LABORATORY ANIMAL SCIENCE:
edited by
Published by
Reviewed by Robert Hall, DVM, Asst. Dir. for Assurance, National Institutes of Health,
Bethesda, MD
[Ed. Note: Robert Hall passed away on March 30, 1994] Developed
countries around the world require that their veterinarians,
technicians, and other animal care providers be adequately educated or
trained to provide the husbandry and care of animals used in research.
Likewise, scientists who design and use animals in their research are
also being required to be educated and trained in laboratory animal
science. Principles of Laboratory Animal Science was written as a text
and basis for a graduate course for this latter group of scientists.
It is hard to conceive of a single book of less than 400 pages that
covers: animal legislation; animal models; biology, husbandry, and
diseases of commonly used animals; experimental design and management;
factors such as stress, nutrition, microbiological contamination and
genetics which impact research results; and recognition of animal pain.
Yet this book succinctly does just that. A solid background in each of
these fields may be necessary to fully appreciate how carefully each
chapter is presented with regard to improving the researchers approach.
For instance, the chapter on þDesign of Animal Experimentsþ discusses
the subject of selecting the correct number of animals to use to
provide valid results. With an understanding of basic principles of
biostatistics, the reader realizes that the appropriate number of
animals to use can be calculated once the correct experimental design
has been selected.
Occasional reference to the Directive for the Protection of Vertebrate
Animals Used for Experimental and Other Scientific Purposes adopted by
the Council of European Communities is the only hint that this book is
targeted for European scientists. Certain standards, such as the
required floor space for housing each species, are applicable only to
that community. Otherwise, the information and recommendations in this
book are universally applicable.
NEW PUBLICATIONS AVAILABLE FROM AWIC
QB 94-02 Welfare of Experimental Animals
QB 94-10 BST - Bovine Somatotropin/Growth Hormone
QB 94-14 Housing, Husbandry, and Welfare of Swine
QB 94-15 Housing, Husbandry, and Welfare of Poultry
QB 94-16 Housing, Husbandry, and Welfare of Rabbits
QB 94-17 Training Materials for Animal Facility Personnel
QB 94-18 Anesthesia and Analgesia for Companion and Laboratory Animals
QB 94-19 Animal Models of Disease
QB 94-21 Anesthesia and Analgesia for Farm Animals
QB 94-22 Housing, Husbandry, and Welfare of Horses
QB 94-24 The Dog
SRB 94-01 Animal Models in Biomedical Research: Swine
The photograph showing drill grooming behavior (AWIC Newsletter Vol4.
#4, P.8) should have been credited to Heidi Englehardt of Grass Valley,
CA.
The United States Department of Agriculture (USDA) prohibits
discrimination in its programs on the basis of race, color, national
origin, sex, religion, age, disability, political beliefs and marital
or familial status. (Not all prohibited bases apply to all programs).
Persons with disabilities who require alternative means of
communication of program information (braille, large print, audiotape,
etc.) should contact the USDA Office of Communications at (202)720-5881
(voice) or (202)720-7808 (TDD). To file a complaint, write the
Secretary of Agriculture, U.S. Department of Agriculture, Washington,
D.C., 20250, or call (202) 720-7327 (voice) or (202) 720-1127 (TDD).
USDA is an equal employment opportunity employer. To file a complaint,
write the Secretary of Agriculture, U.S. Department of Agriculture,
Washington, D.C., 20250, of call (202)720-7327 (voice) or (202)720-1127
(TDD). USDA is an equal employment opportunity employer.
United States Department of Agriculture
OFFICIAL BUSINESS
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ANIMAL WELFARE INFORMATION CENTER NEWSLETTER (ISSN 1050-561X)
is published quarterly and distributed free of charge by the National
Agricultural Library. The Animal Welfare Information Center Newsletter
provides current information on animal welfare to investigators,
technicians, administrators, exhibitors, and the public. Mention of
commercial enterprises or brand names does not constitute endorsement
or imply preference by the U.S. Department of Agriculture. Articles
appearing in this newsletter do not necessarily represent positions or
policies of the U.S. Department of Agriculture or any agency thereof.
Tim Allen, Editor
D'Anna Berry, Production and Layout
Michael Kreger, Assistant Editor
Phone: (301) 504-6212
Xylazine Doses: Cattle Sheep & Goats
Sedation 0.02 mg/Kg IV, 0.1-0.2 mg/Kg IM
0.05 mg/Kg IM
Recumbency, 0.11 mg/Kg IV, 0.22-0.66 mg/KgIM
heavy sedation 0.22 mg/Kg IM
Xylazine 0.22 mg/Kg IM
Ketamine 11 mg/Kg IM
Guaifenesin 100 mg/Kg IV (50 Gm max dose)
POST-OPERATIVE CARE AND ANALGESIA OF FARM ANIMALS USED IN
BIOMEDICAL RESEARCH
University of Oklahoma
Health Sciences Center, Animal Resources
Oklahoma City, OK 73190
Ruminants
aspirin 50-100 (mg/kg) PO 12 hr duration
phenylbutazone 6 (mg/kg) IV,IM,PO
buprenorphine .005(mg/kg) 4 to 6 hrs duration
Pig
aspirin 10 (mg/kg) PO
phenylbutazone 2-5 (mg/kg) IV
buprenorphine 0.1 (mg/kg) IM 12-hour duration
Director of Animal Care Staff, APHIS, REAC
and Sue Gallagher
Program Specialist, APHIS, REAC
Include special considerations for transgenic species.
Use science-based standards where possible.
Redefine the term þanimalþ in the Act to reflect which þanimalsþ
are to be regulated.
Revise the definition of þexemptionsþ in the Act.
Broaden the USDA authority on the use of farm animals for teaching.
Address behavioral enrichment requirements.
Review the current definition of þmajor operative proceduresþ under
the AWA.
Medical records should follow the animal if it is moved to a
different facility.
Address the animal identification issue.
Define humane handling practices.
Use tables/guides, when applicable, e.g., number of animals per
enclosure.
Limit the number of separate subparts for each farm animal species.
A Contribution to the Humane Use and Care of Animals and
to the Quality of Experimental Results
L.F.M. VanZutphen, V. Baumans & A.C. Beynen
Elsevier Science Publishers
May 1993
Correction
USDA EEO Policy Statement
National Agricultural Library
AWIC Newsletter Staff
Beltsville, MD 20705
Penalty for Private Use, $300
ANIMAL WELFARE INFORMATION CENTER NEWSLETTER
ISSN 1050-561X
Fax: (301) 504-6409
Internet: AWIC@NALUSDA.GOV
Animal Welfare
Information Center
United States Department of Agriculture
National
Agricultural LibraryUSDA Cooperative Agreement No. 58-0520-5-076 - July, 1995