Maximizing Quality of Life in III Animals
As a goal of medical care, quantity of life has value in that this goal motivates our strongest efforts at effective treatment, but it has become increasingly clear that maximum length of life is not the goal that serves the patient best. Accordingly, the focus on mortality and morbidity in health care has been steadily superseded by attention to quality of life (QOL).1 A focus on QOL ensures that the patient’s desires guide health care decisions.
“Quality of life” is a term used extensively in the field of health care; however, QOL encompasses much more than health-related issues. The term was first used when discussing conditions for a good life in human society.2 It soon became clear that medicine and health care played a prominent role in individual and societal QOL, and the term therefore became useful in examining the quality and delivery of health care. Over the past 3 decades, QOL moved from its economic and societal meaning to represent the individual’s needs for his or her own life, influenced by a multitude of factors including, but not limited to, health status. The importance for animal care is that QOL involves all spheres of an animal’s life, and efforts to maximize QOL will incorporate many facets of the individual animal’s life.
What is Quality of Life?
Quality of life is a very complex concept, but in its simplest view it may be regarded as one’s general enjoyment of life. In humans, quality of life is interpreted not as an external view of how others judge one’s life, but rather how the individual feels about his or her own life. When an individual cannot directly convey his own perspective of his life (as occurs in neonates, infants, and the mentally disabled), QOL is estimated by others; such external evaluations are intended to reflect the perspective of the individual. The human concepts of QOL have been recently applied to animals.3–5 In humans and animals, QOL has been proposed to be closely related to psychological well-being, happiness, life satisfaction, and contentment.3467 In common usage, emotional fulfillment and peace of mind are closely related to QOL.
Quality of life is very individualized, based on each animal’s unique genetic makeup, personality, and learned experiences, which result in different values and priorities being assigned by the individual to different aspects of its life. An example is the value of human companionship in dogs; in situations where the animal is deprived of human interaction and companionship, one dog may be unaffected, whereas another dog may be emotionally debilitated (such as dogs with severe separation anxiety). Another example is pain tolerance. Some animals react quite dramatically to even minimally painful stimuli; others appear very stoic under situations presumably very painful. Accordingly, the components of QOL will carry different weights for each animal. The experience of QOL is dependent upon what matters to the individual animal, and what matters varies greatly among individuals. Assessing the personal priorities in animals remains a challenge; fortunately, innovative research methodology is providing new insights into determining animals’ personal preferences and values.89
The Role of Feelings
Feeling (i.e., affective) states appear to have evolved to serve as a mechanism whereby the brain of a conscious animal encodes value to the vast array of external and internal stimuli inundating the nervous system. Stimuli that have value or are relevant for survival and reproduction elicit feelings. The pleasant and unpleasant valence signifies the positive and negative influence on survival, and the intensity of the feelings signifies the corresponding degree of importance of the stimulus.10 In this view, feelings evolved to represent those things that matter to the animal for well-being and survival. Because feelings are mentally associated with those things that matter to the animal, it is reasonable to suggest that feelings are the central constituent of QOL in animals. In support of this contention, studies in humans have shown that the quality of emotional pleasantness is one of the strongest predictors of life satisfaction.6 All feelings have a pleasant or unpleasant quality and may be of physical and emotional origins.
Feelings play a central role in QOL for animals. Any factor that does not have an influence on feelings has no effect on an animal’s QOL. This fits ideally with the view that feelings are the mental representations of those things that matter to the animal. Therefore, those things that do not matter to the animal—and hence elicit no feelings, pleasant or unpleasant—would not affect QOL. Illness and injury impact QOL because of the unpleasant feelings (e.g., nausea and pain) that they elicit. Diseases or disorders such as a loss of a toe, a small lipoma, or first-degree heart block do not affect QOL, because they elicit no feelings. Without feelings, the animal is unaware of and his behavior is not influenced by the condition. This applies to many nonmedical matters, such as fancy hair trims, painted toenails, expensive collars, and prosthetic testicles. Unaffected feelings mean unaffected QOL.
Unpleasant feelings appear to have evolved in all conscious animals to be associated with threats to well-being and life. These feelings alert the animal to threats, focus attention on important stimuli, and motivate the animal to take self-protective action to lessen the threat. Sources of unpleasant feelings (i.e., discomforts) in animals may be physical in origin (e.g., hypoxia, thirst, hunger, disease, nausea, full urinary bladder, pruritus, temperature extremes, and pain) or emotional (e.g., fear, anxiety, loneliness, grief, frustration, and boredom). Unpleasant feeling states constitute a continuum of intensity, ranging from extreme discomfort (i.e., suffering) to no discomfort (i.e., comfort). Minimizing discomfort is the foremost goal of all animal care, including health care.
Pleasant feelings appear to have evolved in conscious animals to benefit well-being and life. Pleasure is the agreeable and desirable mental quality of a variety of feelings, ranging from the taste of sweet foods to the experience of sexual excitement. Proposed sources of pleasure in animals include play, social interaction and companionship, mental stimulation, tasty foods, nurturing young (mammals, primarily female), and sexual activity. In humans6 and animals,11 the array of feelings experienced as pleasant increases the overall emotional pleasantness of one’s life experience, thereby elevating QOL.5
Because they are protective against threats and critical to survival, unpleasant feelings command more attention, priority, and urgency than the pleasant feelings of life. Unpleasant feelings do this by inflicting hurt, which assures that the animal pays attention to and acts to rectify the problem. Consequently, unpleasant feelings contribute disproportionately to QOL as compared to pleasant feelings. In addition, as the threat grows (e.g., as the urinary bladder continues to fill or oxygen intake diminishes), the discomfort increases in intensity, causing mental attention to be focused more intensely and narrowly on the threat and less on other matters. If the threat remains uncorrected, the mental focus ultimately is directed solely on the discomfort and is diverted from all other (less urgent) matters. This severely impairs the animal’s ability to enjoy any pleasant experiences, such as the pleasure of the owner’s companionship. As a consequence, the contribution of unpleasant feelings to QOL is extremely aversive.
In calculating the impact of discomforts on QOL, it is important to understand that the distress potential is not the same for all unpleasant feelings. The survival value of unpleasant feelings differs, and their contribution to QOL correspondingly differs. The intensity of the unpleasantness of the feeling corresponds to the degree of the threat to life and well-being. Situations and stimuli that are most urgently threatening to life have come to be associated with the most intensely unpleasant feelings; they include hypoxia from impaired oxygen intake (e.g., secondary to pleural effusion, pulmonary edema, airway obstruction, being trapped under water), pain from actual or potential tissue damage, and fear (the self-protective emotional signal of imminent danger). For some unpleasant feelings, the intensity may increase over time. Examples are thirst and hunger, representing unmet physiological needs. Unmet psychosocial needs appear to create similar feelings. For example, the magnitude of feelings of social isolation (i.e., loneliness) and boredom may be time-dependent, increasing over time.12
The evolutionary survival value of unpleasant feelings has resulted in their having a disproportionately greater contribution to QOL, and due to the urgency of the survival threat, some unpleasant feelings have greater distress potential than others. These mental priorities surrounding unpleasant feelings are critical for the clinician’s attempts to maximize QOL, and the urgency in attending to an animal’s unpleasant feelings needs to be proportional to the distress potential of the feelings.
The Balance Model of Quality of Life
Quality of life appears to be comprised of the pleasant and unpleasant feeling states and, more specifically, the balance between these feelings.11 In this way, QOL may be viewed as a set of scales, with pleasant feelings on one side and unpleasant feelings on the other [Figure 1]. The direction of tipping of the scales represents the QOL. A higher and lower QOL will refer to a tipping of the scales toward pleasant and unpleasant feelings, respectively. This model provides a clear view as to which factors contribute to QOL. Anything that tips the QOL scales—in either direction—is an influence on QOL; anything that does not tip the scales is not relevant to QOL. For example, the reason the addition of a new wall painting to a cat’s household would not affect QOL, whereas the addition of a dominant, aggressive, “bully” cat would, is because the former would not tip the QOL scales and the latter would. The same principle would apply for a dog with a visible scar from a successful surgery (no tipping of the scales) versus a dog with a pruritic skin disease (tipping of the scales). The degree to which the scales are tipped defines the magnitude of influence that factor has on QOL.
Major Contributing Factors to Quality of Life
An array of factors contribute to QOL, all by way of the feelings they elicit. Due to variation in personal preferences, needs, and desires, factors influential to QOL vary in their importance between individuals.
Social Relationships
In social animals, social interaction and companionship appear to be associated with pleasant feelings, and separation and isolation are associated with unpleasant feelings (e.g., loneliness).10 Together, these strong pleasant and unpleasant feelings serve to promote social relationships and, depending on which feeling is activated, have the potential to tip the QOL scales in either direction.
Mental Stimulation
The brains of higher animals function optimally when receiving a specific amount of stimulation; when too much or too little stimulation is presented to the brain, disorganization, instability, disease, and suffering may result.13 When deprived environments provide insufficient stimulation in humans, the unpleasant feeling of boredom is elicited. Studies in the behavior and physiology of animals support the contention that boredom acts similarly in non-human species.1415 Boredom in animals,1416 as in humans,17 can be a cause of severe emotional distress, sometimes but not always manifesting as abnormal behavior patterns (e.g., stereotypies, redirected behavior, and depression or passivity15). As a source of distress, boredom may exert a powerful influence on QOL. Conversely, mental stimulation is very rewarding to animals, appearing to elicit highly pleasurable feelings.18 Stimulation can be in the form of play, exploration, and many other forms of mental engagement and challenges.
Health
Health status may influence QOL in a number of ways. The discomforts of illness contribute powerful unpleasant feelings to the person’s or animal’s overall life experience.1920 Such feelings include hypoxia, nausea, pain, weakness, constipation, and pruritus. In addition, physical impairments and disabilities associated with disease have the potential to limit opportunities for experiencing pleasurable events and activities. In the scales model of QOL, such limitations of pleasurable experiences may lessen QOL by negatively tipping the scales. Examples of medical conditions that impair the ability to experience pleasure include paralysis, degenerative myelopathy, congestive heart failure (CHF), blindness, and deafness. Some medical conditions may cause no feelings of discomfort to the animal but may lead to unpleasant feelings indirectly, such as malodorous skin or urinary incontinence, which may result in social rejection or banishment to outdoors by the pet owner. In such cases, the health disorder may have no direct influence on QOL but may affect it indirectly by the isolation and loneliness that results.
Food Consumption
Because energy intake is critical to survival, powerful feelings evolved to promote food consumption. The pleasant taste of food and the unpleasant feeling of hunger each motivate consumption of adequate and, in the natural setting, balanced nutrition. Overeating can cause obesity, which impairs QOL by increasing discomforts (e.g., joint pain21) and predisposing to health problems. In addition, obesity can limit opportunities to experience pleasurable activities, such as walks, runs, and energetic play. The relationship of food intake to QOL is complex and not a straightforward positive or negative association. For example, a recent study in dogs22 demonstrated that a lifelong 25% restriction in food intake resulted in a delayed onset of osteoarthritis and other chronic diseases, and increased longevity. If such a food restriction were to result in a chronic hunger state, the benefits to QOL of the delayed onset of health disorders (a lessening of the unpleasant feelings of disease) would be weighed against the detrimental effects of hunger (an unpleasant feeling state) upon QOL.
Stress
“Stress” is commonly used as a catch-all term when what is really involved is a specific, unpleasant emotional experience, such as fear, anxiety, pain, loneliness, frustration, boredom, or anger.2324 The feeling associated with the specific emotion is the element of stress that affects QOL. Therefore, in maximizing QOL, it is not stress which is alleviated, but rather the specific unpleasant emotional feeling.
The contribution of stress to QOL is not a simple inverse relationship. Much evidence supports the contention that some degree of stress is necessary and beneficial to animal well-being and that too little stress can be unpleasant to the animal and detrimental to well-being (and, hence, QOL).315 The most important aspect of stress as it pertains to QOL appears to be the animal’s ability to respond to the demands of its environment (that is, to cope effectively with stressors). In this view, QOL is improved by successfully coping with life’s problems rather than from experiencing no problems or difficulties in life. Studies in primates suggest that a challenging environment with some adversity is more supportive of a high QOL than a monotonous and unchallenging environment.25 The extensive literature on stress in animals suggests the counterintuitive notion that maximizing QOL does not mean preventing all stress in the animal’s life, but, rather, permitting some stress (i.e., unpleasant emotional experiences) while providing the animal with the means to cope with the challenges and stresses of life.
Control
A large body of research in animals and humans has demonstrated that a sense of control over one’s life and circumstances, especially the unpleasant feelings and events, is one of the most reliable predictors of positive feelings of well-being and health.2627 As it is used in animals, control is the perceived ability to influence one’s environment or one’s relationship with the environment. Control permits the animal to influence the psychological impact of stimuli, by increasing the intensity of pleasant feeling states and decreasing the intensity of unpleasant states. For animals, a sense of control over adverse conditions, specifically the ability to minimize the unpleasant feelings of distress, appears to be one of the most critical components of mental well-being.2728 In humans and presumably in animals, a sense of control provides positive expectations about one’s circumstances and creates hope that unpleasant life events will not endure. Animals deprived of any control over their own circumstances, especially under persistent or repetitive aversive conditions, may develop severe emotional distress in the form of helplessness and hopelessness.27 Helplessness in animals is a debilitating emotional state that has been equated to, and is used as a model for, clinical depression in humans.27 For humans and animals, the sense that one has control, even if it is not exerted, is highly effective in reducing the intensity and harmful effects of physiological and emotional stress.2930 Control incorporates the animal’s ability to escape from or otherwise lessen the degree of unpleasantness of a stimulus, but it also incorporates the availability of choice. Having choices imparts control and permits the animal to increase pleasurable experiences, as the animal can select certain activities or stimuli over other less desirable options. Some studies have suggested that animals will exercise control simply for the apparent enjoyment of the control itself. For example, many studies show that animals will choose to work for food even when the same food is freely available.31 A more dramatic illustration of the desirability of control is a study in white-footed mice.32 The mice were given control over certain aspects of their captive environment, such as light intensity. If the experimenters increased the brightness of the cage lighting, the mice would dim them to darkness. If the experimenters made the room dark, the mice would turn the lights up bright. If the mice were awakened from sleep and emerged from their nest boxes, they would soon go back inside on their own. If, however, the experimenters picked the mice up and placed them in the nest box, they would immediately come back out, even if they were placed repeatedly back in the box. The results suggested that the mice chose to exert control for control’s sake, even if it meant more work or having the lights at levels they showed a preference against when experimenters were not present.
Control for animals means that they have the ability (or perceived ability) to increase or decrease their pleasant and unpleasant feelings. In practical terms, providing a sense of control means providing the animal with the means to end or lessen emotional distress and offering choices for enjoyable (or at least less undesirable) stimuli and situations.
In all, control has a powerful impact on QOL. The absence of control, especially in conditions of adversity, may create severe emotional distress and be extremely detrimental to QOL.27 Conversely, having a reasonable amount of control alleviates stress31 and appears to provide increases in pleasure.
Maximizing Quality of Life—General Principles
The first step toward QOL maximization is to be able to assess QOL, which then enables the veterinarian to gauge the success of the enhancement efforts. However, accurately assessing QOL has proven to be difficult in humans as well as in animals. Measuring even a single component of QOL, such as pain, is problematic;33 therefore, the much more complex totality of QOL is exceptionally difficult to accurately measure. Unfortunately, there is no current ability to quantify either QOL as a whole or the individual contributing factors. In humans, the usual method of acquiring QOL information is through patient self-assessment questionnaires; however, animal patients cannot directly provide this information. Assessment of the animal’s QOL must come indirectly, through the pet’s closest human caregiver. A quick assessment QOL questionnaire for use by pet owners is provided in Appendix 1.
Despite the difficulties in quantifying QOL, it is fortunate that these problems do not greatly hamper the clinician’s ability to maximize QOL, as the principle applied is effective at all levels of QOL. Maximizing QOL can be summarized by a single principle: Tip the QOL scales as far toward the pleasant side as possible. Based on the balance model of QOL, this may be achieved by minimizing unpleasant feelings, promoting pleasant feelings, or a combination of the two. This basic principle applies to all animals, healthy and ill. For animals with a health disorder, the main effort is to restore a diminished QOL by alleviating the unpleasant feelings associated with the disease. For healthy animals, the main emphasis is promoting pleasures. In all cases, QOL rises as the scales tip increasingly toward the positive direction.
Although veterinarians currently lack the ability to accurately quantify feeling states, certain guidelines can help to approximate the contribution of feeling states to QOL [Appendix 2] and formulate an individualized strategy for maximizing QOL. It is important to first survey and identify all sources of feelings in the animal’s life—pleasant and unpleasant, health-related and nonhealth-related. Because of their disproportionate contribution to QOL, unpleasant feelings warrant the highest priority. Moreover, because of their greater distress potential, the most urgent attention should be directed to feelings evolutionarily associated with greatest survival urgency, such as difficulty breathing, pain, and fear. Time-dependent emotions, such as boredom and loneliness, should receive a degree of attention equal to the duration they have persisted. Important final considerations are each animal’s individual personality and preferences. All factors eliciting the feelings contributing to QOL matter to different degrees for individual animals. For example, something that is a great source of joy to one cat may be meaningless to another cat; likewise, something that elicits severe emotional distress in one dog may have no effect on another. These individual needs, desires, values, and preferences are critical when devising a plan to maximize QOL.
Each of the major contributing factors to QOL discussed in the previous section should be individually addressed. Each factor has pleasant and unpleasant feelings associated with it, and these deserve special attention when attempting to tip the balance of the QOL scales. The Table presents each major contributing factor and specific approaches to QOL enhancement for each.
Frequently, a medical disorder exists that has not yet caused clinical illness. An example is a severe thrombocytopenia detected in an asymptomatic animal on a routine preanesthesia blood screen. The asymptomatic condition may have no current impact on QOL (because no feelings have been elicited, the animal is unaware of the condition, and hence QOL is unaffected). However, the fact that QOL is currently not influenced does not mean that it never will be, and attention to such a condition is indicated to prevent a future impairment to QOL. With other examples, such as immunizations, strategies for maximizing QOL often incorporate a preventive approach before QOL becomes affected.
Maximizing Quality of Life in the Ill Animal
In the ill animal, the QOL balance is tipped toward the unpleasant side because of the increase in unpleasant feelings associated with the disease state. This may consist of a single high-intensity discomfort or multiple low-intensity discomforts; a diminished ability to enjoy pleasant feelings and experiences because of the tendency to focus attention progressively more on the discomfort and progressively less on pleasant feelings; and the impaired opportunities to experience pleasure because of the disabilities associated with the medical disorder. Because of the powerful effects of the unpleasant feelings, the emphasis of maximizing QOL in the presence of disease is directed toward the alleviation of the discomforts associated with the disease. Restoration of health is the most effective means to regain the diminished QOL, but the alleviation of unpleasant feelings is also effective when cure is not attainable. Numerous interventions may help achieve this objective. For example, medications and oxygen supplementation can aide oxygenation and thereby reduce unpleasant feelings; analgesics, antiemetics, laxatives, anxiolytics, antihistamines, corticosteroids, and chemotherapy agents can help to relieve discomforts; and gentle and soothing human contact such as stroking, petting, and talking to the animal can attenuate feelings of pain, anxiety, fear, and loneliness.3435 Attention should be prioritized according to the distress potential of the specific unpleasant feelings.
Determining—or predicting—the net effect of a therapeutic intervention on the QOL balance is not always straightforward. Therapeutic interventions often have negative as well as positive influences on QOL. Countless examples exist, such as the distress and taste displeasure in receiving certain oral medications, the polydipsic and polyphagic effects of glucocorticoids, the loss of vision resulting from enucleation, a worsening of renal failure when treating feline hyperthyroidism, play restriction and cage confinement in managing orthopedic disorders, and the risk of fibrosarcoma from routine vaccinations. Such negative effects on QOL are critical to weigh in when therapeutic decisions are made.
It is also important to include mental health in the spectrum of animal health disorders. Emotional illnesses, such as phobias and separation anxiety, elicit unpleasant feelings that are as distressing as physical illness. Alleviating discomforts of mental illness is of equal importance as those of physical illness for elevating a diminished QOL. The intense fear experienced in phobic disorders, especially when the condition is unrelenting, may be a profound suffering. Recently described methods to alleviate the unpleasant feelings of emotional illness include pharmacological and nonpharmacological interventions.36
Although the primary focus for QOL in ill animals is the alleviation of unpleasant feelings, the vastly underappreciated potential for QOL maximization—a key element to tipping the QOL scales toward the pleasant side—is the promotion of pleasant feelings. In human patients with terminal disorders, for example, QOL is often substantially elevated through increased social support, fun activities, and humor during the course of illness. Providing the ill animal with more pleasurable experiences will enhance QOL (this is what “pampering” is—an effort to flood the animal with pleasurable feelings). Sources of pleasurable feelings include social interaction and companionship (with humans and other animals), mentally stimulating and engaging activities (e.g., variety, challenges, play, chase-and-pounce games, fetch games, hunting for hidden objects and food treats, outings, interactive toys, leash walks outside, and a continuous supply of novel objects to investigate and explore, such as cardboard boxes or tree branches), taste pleasures (e.g., palatable foods and snacks), human contact (e.g., petting, massage, laying in lap), climbing, digging up things, lounging in sunlight, and enjoyable sights, sounds, and smells.3738 Because of the individual nature of QOL, the type and quantity of pleasure-eliciting stimuli must be individualized for each animal. Accordingly, the person who is most familiar with the animal’s unique personality and nature is best suited to compile the list of pleasures to be used in the QOL maximization program.
Pleasurable experiences are not limited to what human caregivers actively give to animals; ideally, the animal’s life should consist of opportunities for the animal to generate positive, pleasurable experiences for itself. This provides the crucial mental health factor of control, empowering the animal to positively engage its environment when it chooses. If an animal’s life lacks meaningful opportunities to generate pleasurable experiences, then QOL may not be able to reach its maximal potential. Specific methods for enabling the animal to engage its environment include interactive toys, owners responding to the animal’s signals for play and going on walks, and providing choices for foods and visual stimulation (e.g., videotapes, fish tanks, and windows) and, if feasible, a door with access to the outdoors.38
For patients with disabilities, such as paralysis disorders or blindness, the goal is QOL restoration. The disability diminishes QOL, because the lost or impaired abilities limit the opportunities to experience pleasures such as chasing, running, and playing. These losses can be at least partially restored through such measures as carts and sling-walks for paraplegic patients and hand signs for communication with deaf animals [Figure 2]. Quadriplegic dogs can be taken on frequent outings and “walks” in a wagon.
It is important to be sure that pleasant activities are suitable for the specific disease or disability. Chasing a ball, for example, may be inappropriate for a patient with CHF. Any pleasurable feelings that can be increased without risking additional unpleasant feelings should be fully promoted. Even activities which elicit unpleasant feelings may be beneficial to QOL, as long as the net effect is to tip the QOL scales toward the pleasant side. For example, if going on walks leads a dog to feel some discomfort of arthritis, but the walks are highly pleasurable and desired, then continuing the walks would be expected to result in a net improvement of QOL.
As disease states progress, the QOL scales will tip increasingly toward unpleasant feelings. This will be due to increasing magnitude of the unpleasant feelings and decreasing pleasurable feelings. Eventually, efforts to increase QOL will be insufficient to counteract the progressively negative tipping of the scales. At the point when the unpleasant feelings substantially outweigh the pleasant feelings, QOL is sufficiently poor to justify consideration of euthanasia.
Conclusion
The paramount objective in veterinary care is to maximize QOL. This goal is accomplished, in both ill and healthy animals, by the dual effort of minimizing unpleasant feelings and promoting pleasurable feelings. This keeps the QOL scales tipped as far toward the pleasant side as possible, giving the animal the greatest possible emotional pleasantness in life. By expanding medicine’s focus to include the promotion of pleasant feelings in addition to the traditional medical objective of treating disease, the veterinary clinician’s ability to improve QOL in ill animals is greatly enhanced. Pet owners and veterinarians should work as a team to maximize each animal’s QOL, paying attention to the individual nature of every animal. As research continues to elucidate the feelings of animals and the impact of disease states, the veterinarian’s ability to assess and maximize QOL will steadily improve. As it does, the potential for animals with medical disorders to lead the most enjoyable lives will be greatly enhanced.
Citation: Journal of the American Animal Hospital Association 39, 3; 10.5326/0390227
Citation: Journal of the American Animal Hospital Association 39, 3; 10.5326/0390227
Balance model of quality of life.
Quality of life is enhanced in paraplegic animals by use of a cart.
