The dominant world view of antiquity and the Middle Ages was that of Aristotle, who stressed explaining the world as we find it through ordinary experience, a world of qualitative differences—hot and cold, wet and dry, living and nonliving. With the advent of the scientific revolution and the ascendance of an explanatory model based in mathematical physics, the qualitative was replaced by the quantitative. Correlatively, this revolution was inexorably replicated in all of the sciences, including biology and medicine. Insofar as human and veterinary medicine became sciences in the 20th century, they too became increasingly reductionistic and thereby less attentive to qualitative considerations. As the art of medicine became more and more the science of medicine, subjective states became less and less the focus of medical attention, a tendency buttressed and augmented by an ideology declaring science to be value-free in general and ethics-free in particular.¹

The tendency of physicians and other human healthcare providers to focus on fixing the body and ignoring the person and his or her subjective states is almost a cliché. Uncomfortable with private, amorphous, and ill-defined notions like suffering and even pain, physicians focused on cure rather than care and judged their success in terms of measurable criteria such as prolongation of life. This is beginning to change, but pain control is still not a priority.

Exactly the same movement historically characterized veterinary medicine. Control of animal pain and distress was largely ignored, a tendency that meshed perfectly with veterinary medicine's traditional agricultural roots and related role as restoring the economic function of sick animals. The first US textbook on veterinary anesthesia² failed to include information on pain felt, even in passing. Dr. Frank McMillan³ has deftly demonstrated the degree to which veterinary medicine ignored the animal mind to its own detriment.

Various factors have converged to create a growing emphasis on animal subjectivity in veterinary medicine. In the first place, companion animal practice has emerged as the dominant social function for veterinary medicine, as pets have assumed ever-increasing importance in human life, and the value of such animals to people is not primarily economic.⁴ Second, social concern about animal welfare has driven increasing attention to subjective states that presumably constitute the animal's life world—awareness of pain, fear, boredom, loneliness, hunger, thirst, anxiety, and discomfort, or on the positive side, joy, sexual excitement, companionship, lacking of thirst or hunger, alleviation of boredom, comfort, and contentment, for example. As Wemelsfelder⁵ has shown in her detailed, pioneering analysis of boredom, such mental states can be scientifically and precisely defined, or at least identified with testable criteria for their presence.

In today's cultural milieu, advances in human medicine are transferred and appropriately modified to veterinary medicine, for example, in dialysis or radiation therapy. (Sometimes, as in the case of limb-sparing treatment of osteosarcoma, developed at Colorado State University for dogs, veterinary medical advances have been exported to human medicine.) Human medicine has been forced by public pressure to worry about quality of life as well as its prolongation. Indeed, the movement on behalf of voluntary euthanasia, or choosing to die, is a direct result of society's rejection of the medical concept that more life, or prolongation of life, is justified at any cost to its quality. The hospice movement also evidences increasing attention to quality of life when death is inevitable.

There is, however, a striking dissimilarity between humans and animals facing life-threatening illnesses, even as the tools of medicine dealing with such crises converge in the two medical disciplines. Human cognition is such that it can value long-term future goals and endure short-run negative experiences for the sake of achieving them. Examples are plentiful. Many of us undergo voluntary food restriction, and the unpleasant experience attendant in its wake, for the sake of lowering blood pressure or looking good in a bathing suit as summer approaches. We memorize volumes of boring material for the sake of gaining admission to veterinary or medical school. We endure the excruciating pain of cosmetic surgery to look better. And we similarly endure chemotherapy, radiation, dialysis, physical therapy, and transplant surgeries to achieve a longer, better quality of life than we would have without it or, in some cases, merely to prolong life to see our children graduate, complete an opus, or fulfill some other goal.

In the case of animals, however, there is no evidence, either empirical or conceptual, that they have the capability to weigh future benefits or possibilities against current misery. To entertain the belief that “my current pain and distress, resulting from the nausea of chemotherapy or some highly invasive surgery, will be offset by the possibility of indefinite amount of future time,” is taken to be axiomatic of human thinking. But reflection reveals that such thinking requires some complex cognitive machinery. For example, one needs temporal and abstract concepts, such as possible future times and the ability to compare them; a concept of death, eloquently defined by Heidegger⁵ as “grasping the possibility of the impossibility of your being”; the ability to articulate possible suffering; and so on. This, in turn, requires the possibility to think in an if-then hypothetical and counterfactual mode, that is if I do not do X, then Y will occur. This mode of thinking, in turn, seems to necessitate or require the ability to possess symbols and combine them according to rules of syntax.

I have argued vigorously elsewhere against the Cartesian idea that animals lack thought and are simply robotic machines.^6,7 I strongly believe that animals enjoy a rich mental life. It is also clear that animals have some concept of enduring objects, causality, and limited futural possibilities, or else the dog would not expect to get fed, the cat would not await the mouse outside of its mouse hole, and the lion could not intercept the gazelle. Animals also clearly display a full range of emotions, as Darwin famously argued.⁸

But it is also equally evident that an animal cannot weigh being treated for cancer against the suffering it entails, cannot affirm a desire (or even conceive of a desire) to endure current suffering for the sake of future life, cannot understand that current suffering may be counter-balanced by future life, and cannot choose to lose a limb to preclude metastases.

None of this is intended to denigrate animals or their minds; it is simply meant to mark a difference. The common-sensical truism that animals think and feel was swept away by a scientific revolt against 19th century excesses of anthropomorphism of the sort that attributed larcenous intentions to pack rats or conscious industrious virtue to beavers. To assure the stability of belief in animal mind, we must be careful not to overemphasize its abilities, as when a woman I knew believed a dog could grasp the concept of its birthday celebration. To be sure, the dog could enjoy the treats and attention coming in the wake of the party, but that does not mean that it could comprehend its birthday.

To treat animals morally and with respect, we need to consider their mentation limits. Paramount in importance is the extreme unlikelihood that they can understand the concepts of life and death in themselves rather than the pains and pleasure associated with life or death. To the animal mind, in a real sense there is only quality of life, that is whether its experiential content is pleasant or unpleasant in all of the modes it is capable of, for example whether they are bored or occupied, fearful or not fearful, lonely or enjoying companionship, painful or not, hungry or not, or thirsty or not. We have no reason to believe that an animal can grasp the notion of extended life, let alone choose to trade current suffering for it.

This, in turn, entails that we realistically assess what they are experiencing. We must remember, for example, that an animal is its pain, for it is incapable of anticipating or even hoping for cessation of that pain. Thus, when we are confronted with life-threatening illnesses that afflict our animals, it is not axiomatic that they be treated at whatever qualitative, experiential cost that may entail. The owner may consider the suffering a treatment modality that entails a small price for extra life, but the animal neither values nor comprehends extra life, let alone the trade-off this entails. The owner, in turn, may ignore the difference between the human and animal mind and choose the possibility of life prolongation at any qualitative cost. It is at this point that the morally responsible veterinarian is thrust into his or her role as animal advocate, speaking for what matters to the animal.

Dr. Frank McMillan has reminded us that euthanasia is not an end in itself, but rather a means to ending suffering.⁹ This was probably better understood by earlier generations, where the thought of heroic procedures to save animal life did not enter peoples' minds, nor was there technology available to pursue such modalities. But with the contemporary role of pets as friends, family members, and emotional supporters for humans and the omnipresence of veterinary modalities to replicate human medical innovations (for example, dialysis, transplantation, radiation therapy, and chemotherapy), it is too easy to err in the wrong direction. Whereas once a veterinarian needed to advocate for treatment of the treatable in the face of financial or aesthetic reluctance (even to this day, some owners need to be persuaded that a dog can function with three limbs), today a veterinarian must be vigilant against the owner going too far, at the expense of the animal's quality of life.

One of the most bitter arguments I have ever had with a veterinarian occurred when I was lecturing on euthanasia at a conference. I was accused of male chauvinism and dominionistic paternalism for merely suggesting that veterinarians should, in some cases, direct owners to euthanasia when the animal was experiencing uncontrollable suffering. The veterinarian in question proudly boasted of feeding and hydrating a 20-year-old cat with a spinal tumor because the owner was very bonded with the cat. To my protest that she needed to help the owner understand that the animal was suffering, she proudly proclaimed that she would stabilize the animal for a trip to Lourdes if the owner desired it. Such an attitude helps explain why some veterinarians are reluctant to oppose untested or unproven alternative modalities requested by clients.¹⁰

Plato pointed out that in a shepherd's capacity as a shepherd, qua shepherd, his or her job was to care for and benefit the sheep; any financial reward to the shepherd, in virtue of this activity, was in his or her capacity as wage earner and conceptually separable from being a shepherd.¹¹ By parity of reasoning, a veterinarian's role is to help promote an animal's quality of life by treatment, if this is possible, or by euthanasia when treatment is not possible. The lore in some veterinary circles that a practitioner should never suggest or advocate euthanasia or else the client will later blame the veterinarian for killing his or her animal, while widespread, is indefensible in the face of the aforementioned Platonic reasoning. This also explains our horror at a veterinarian's setting up hits on horses for insurance purposes, as certain scandals revealed historically.

The best way to accomplish advocacy is to set up the type of relationship with a client that has both agreeing to keep the best interests of the animal in view as the paramount goal of treatment. In this way, the veterinarian can educate the client on the nature of animal mentation, suffering, and what matters to the animal. Such education should begin along with treatment, as should the veterinarian's claim for advocacy for animal quality of life. This is not to say that the veterinarian should unilaterally declare that the animal needs to die, but rather that he or she should engage the client in an ongoing dialogue regarding quality of life versus suffering. Nor should the veterinarian ever forget the powerful tool that is Aesculapean authority—the unique authority vested in any healer—that allows a physician to scold or intimately probe even an Adolph Hitler or a captain of industry. It is sometimes the case that veterinarians underestimate the degree to which they enjoy such authority.¹²

Quality of life considerations should be introduced at the beginning of a veterinarian-client-patient relationship, not suddenly sprung on a client when treatment is over. In particular, it is useful to recall Plato's dictum that, when dealing with ethics and adults, it far better to remind than to teach.¹³ For this reason, the client, who knows the animal better than the veterinarian, should be encouraged from the beginning to help define quality of life for that animal. For example, I once adopted a huge, battered, and scarred junkyard dog who was enormously stoic in nature. When he developed degenerative spinal myelopathy and was paralyzed in his hind limbs, I would come home five times a day to move him around the lawn. I asked a veterinarian friend when it was appropriate to euthanize him. He replied that he will tell you. The dog ate and drank, seemed to enjoy the sunshine, and gave no sign that his quality of life was negatively balanced. As it happened, one of his favorite games was catching a handball; offering it to my wife; and then, as she reached for it, snarling and growling like a werewolf, though eventually allowing her to have the ball. He loved to repeat this routine. One day, he would not catch the ball, would not pick it up, and would not offer it to my wife. A week later, he stopped eating and drinking. It was only then I realized that he had indeed told me, but I was too ignorant and selfish to listen.

From the outset, I would then recommend that the veterinarian obtain from the client a list as long as possible of what makes the animal happy or unhappy and how the client knows. This list, written down as part of the medical record, can serve to remind the owners of their own criteria for quality of life at the point when treatment is failing and when wishful thinking and essentially selfish desires may replace objectivity. I used this method with a friend who asked me how to judge when it was time for euthanasia and how to avoid compromising his animal's quality of life by overly prolonging treatment. He later thanked me and told me that, were it not for his own encoded notes defining the animal's quality of life while it was still well, he would have rationalized trying a variety of modalities that would have greatly impaired the animal's quality of life. Unquestionably, he said that denial would have distorted his perception, but for his own reflective, codified deliberations on that animal's quality of life which, even in extremis, was impossible to ignore.

In the end, such dialogue, while awkward, difficult, and emotional, can nevertheless benefit the animal, owner, and veterinarian's own peace of mind.