Seeks to clear up misunderstandings on human rabies vaccinations

I have found considerable misunderstanding on the part of veterinarians regarding the need to be tested for serum antibody concentrations to the rabies virus following pre-exposure vaccination. Regrettably, the JAVMA News article ¹ about human rabies vaccinations may have unintentionally added to this confusion. The article mentions that the AVMA Group Health & Life Insurance Trust offers rabies titer tests at the AVMA Annual Convention, and the executive director of the Michigan VMA indicated that it “offers the tests at its conference.” I worry that many veterinarians reading the article will conclude that one should maintain detectable antibody to be protected against rabies exposure. This is not true.

To her credit, Dr. Connie Austin, the Illinois state public health veterinarian who was interviewed for the article, makes reference to the CDC Web site as a source of information on who should “receive pre-exposure vaccinations, vaccines licensed for use in the United States, serologic testing, and precautions.” Unfortunately, the CDC's recommendations for serologic testing and booster immunization are not detailed in the article.

The recommendations of the CDC's Advisory Committee on Immunization Practices state that veterinarians, veterinary students, and animal-control and wildlife officers working in areas with low rabies rates (infrequent exposure group) should receive pre-exposure vaccinations. However, routine serologic testing and pre-exposure booster doses of vaccine after completion of primary pre-exposure vaccination are not recommended.² The rationale for this approach is that risk of exposure is very low in this population group, the source (either bite or nonbite) will nearly always be recognized, and the two-dose postexposure immunization for previously vaccinated persons will provide adequate rabies protection regardless of serum antibody concentrations.

Serologic testing and periodic booster injections following a primary rabies immunization course are only recommended for populations who are at continual risk of rabies virus exposure, and these exposures are likely to go unrecognized. Typical examples of individuals in this group are rabies research and diagnostic laboratory workers, spelunkers, and veterinarians and animal-control and wildlife workers in rabies-enzootic areas. Most practicing veterinarians would not fall in this group. I cannot recall ever reading a report of a practitioner dying of rabies because he or she did not know they were exposed.

Having said all of this, I realize protection against rabies is a peace of mind issue with many veterinarians and their staff. Rational recommendations will do little to calm the fears of some. However, all of us will benefit by at least knowing the recommendations of experts.

Michael G. Groves, DVM, MPH, PhD, DACVPM, DACVM

Dean, School of Veterinary Medicine, Louisiana State University, Baton Rouge, La

Thoughts on euthanasia and quality-of-life commentary

Professor Rollin's contributions to veterinary ethics are well known and have caused improvements in veterinary practice. I agree with much of what he says. In his most recent JAVMA article,¹ he postulates that a reason for euthanasia is that the quality of life is gone and the animal will tell the owner. However, a problem with this approach is that it assumes the owner is smart enough to realize what the animal is saying. Many owners are ignorant of animal behavior, and some are obdurate in their unwillingness to euthanize a suffering but beloved pet.

As a member of two AVMA Panels on Euthanasia in the 1970s and a onetime small animal clinician who has euthanized hundreds of clients' animals, I realize that the decision to do so is “an enigma wrapped in a conundrum.” Frankly, when faced with a large, old, downer dog, as Dr. Rollin was, I probably would have euthanized the animal sooner for sanitary reasons because it could not rise. I could have been accused by some of doing it for convenience, while others would laud me for realizing that the animal's quality of life was finished.

Dr. Rollin has two mistakes in his article that I would like to correct. He states that the first book on veterinary anesthesia published in the United States was Lumb and Jones' “Veterinary Anesthesia.”² I wrote the first veterinary anesthesia book published in the United States, the title of which was “Small Animal Anesthesia.”³

Furthermore, he states that “Veterinary Anesthesia” does not contain information on pain felt, whatever that means. The word anesthesia comes from the Greek anaisthesia, meaning insensibility or not feeling. Both books have sections that deal with pain in animals. The introduction to the first chapter of “Small Animal Anesthesia” states, “Anesthesia is one of the great miracles of medicine. It has reduced pain in both man and animals and has enabled surgeons to save untold numbers of lives.” An entire section on the physiology of pain and its alleviation through use of anesthetic agents in animals is included in “Veterinary Anesthesia.” It also contains a chapter on euthanasia. A subsequent edition of “Veterinary Anesthesia”⁴ contains revised discussions of pain mechanisms, plus reasons for and methods of euthanasia. A more recent edition of “Lumb and Jones' Veterinary Anesthesia”⁵ contains a 20-page chapter titled “Perioperative Pain and Distress,” plus a 20-page chapter titled “Euthanasia.”

Books written on anesthesia over 30 years ago are obviously out of date. However, as new anesthetic techniques have been developed, the most important goals are relief of pain and suffering. The veterinary profession is truly blessed with the ability to perform anesthesia and euthanasia on animals.

William V. Lumb, DVM, PhD, DSc, DACVA, DACVS

Emeritus Professor Colorado State University, Fort Collins, Colo

Dr. Rollin responds:

Dr. Lumb is indeed correct regarding the first textbook of veterinary anesthesia, and I apologize for overlooking his 1963 volume.¹ I also accept his point that some clients may be unwilling or unable to understand the message sent by the animal. The requisite translational function is clearly part of a veterinary clinician's job and is greatly enhanced by deployment of his or her Aesculapian authority.

I never denied the fact that there is a substantial discussion of the mechanisms and pathways of pain—what I have elsewhere called the plumbing of pain—in “Veterinary Anesthesia”² or in many other volumes. What is absent in this and other books, however, is any discussion of the fact that pain hurts the animal. That is what I meant by “felt pain.” This is clearly evidenced by Dr. Lumb's failure to discuss analgesics (ie, drugs that moderate felt pain or raise the pain tolerance threshold). In fact, analgesics were not deployed in that era in veterinary practice. That felt pain is not identical to pain mechanisms is further evidenced by discussions in the literature of general anesthetics with high or low analgesic properties, where clearly what is under discussion are physiologic signs of pain such as increased heart rate since, by hypothesis, there is no pain felt under general anesthesia.

Further evidence for the distinction I am making may be found in the fact that though the International Association for the Study of Pain widely discussed and used animals as models for studying pain, it also denied in its definition of pain that anything not possessing language could feel pain.³ The neglect of felt pain is again buttressed by the fact that many veterinarians trained more than two decades ago used chemical restraint as a synonym for anesthesia.

I agree that the 1996 edition of “Lumb and Jones' Veterinary Anesthesia”⁴ does indeed contain much material on felt pain and its control, but that is a non sequitur. The fact remains that it was not discussed in Dr. Lumb's 1973 book nor in the 1963 book that I have now examined with interest. Nonetheless, veterinary medicine owes a substantial debt of gratitude to Dr. Lumb's pioneering work.

Bernard E. Rollin, PhD

University Distinguished Professor, Colorado State University, Fort Collins, Colo

I enjoyed reading Dr. Rollin's commentary on euthanasia and quality of life.¹ For the most part, it was a very carefully and thoughtfully written commentary. There was one idea with which I would disagree and one questionable area that I would like to address.

First, it was good that Dr. Rollin wrote, “I strongly believe that animals have a rich mental life,” making a belief rather than an a priori statement. The meaning of the word rich, of course, has a wide range of interpretation in this particular context. However, the statement that “animals clearly display a full range of emotions…” is inconsistent with his idea that “to treat animals morally and with respect, we need to consider their mentation limits.”

While I agree with the latter idea, I would argue that animals may have some emotive capacity, but they do not have the capacity for empathy. Empathy requires some understanding of another's distress, and animals simply do not have the cognitive capacity to put themselves in our place. Pets can and often do react to their owners' distress or discomfort, but that is not to be confused with experiencing the emotion of empathy. Such anthropomorphic assignments are understandably confusing to many clients.

I'm not certain how Dr. Rollin is suggesting to introduce “quality of life considerations…at the beginning of a veterinarian-client relationship….” Certainly, when presented with a seriously, moderately, or chronically ill pet, it is an appropriate discussion. However, it's not clear whether the beginning of such a relationship would include, for example, a first-time puppy visit. If so, I would have to question the value of such a discussion regarding a presently healthy pet, as it lends itself to being very awkward and perhaps inappropriate, at least in the client's mind.

Dr. Rollin's story about his own dog's debilitating condition was interesting. In our practice, we use similar criteria as his veterinarian when presented with the question of “when is it time to euthanize?” In my experience, clients, for the most part, are able to determine an appropriate time on the basis of our professional guidance and their at-home assessment of their pet's enjoyment of the things that they usually enjoy, such as eating and watching birds.

Although making a quality-oflife list may be unnecessarily awkward, I do agree that for certain clients, it may be a valuable tool when it comes time to the discussion of euthanasia. In our clinic, such a practice will not become standard operating procedure, but it is nonetheless an interesting and potentially useful idea.

John S. Parker, DVM, Novi, Mich

Dr. Rollin responds:

I am grateful to Dr. Parker for his attentive reading of my paper and for the opportunity his letter affords me to clarify my meaning. I never claimed in my discussion that animals were capable of empathy—such a claim is of no relevance to my argument in the essay. As a matter of fact, however, the jury is still out on that question; there is some very suggestive evidence that at least some animals, such as higher primates and elephants, do.

I also did not affirm that a veterinarian should begin discussing euthanasia when a client brings a new puppy to the clinic for the first time. Obviously, a client in such a position would not yet know what makes the animal happy or what evidences unhappiness. What I said was that “from the outset, a veterinarian should obtain from the client a list … of what makes the animal happy.” By “from the outset,” I meant at the beginning of treatment for a chronic problem that might eventually require euthanasia. Many pediatricians discuss puberty with parents but not when the baby is brought to the office as a newborn.

Bernard E. Rollin, PhD

University Distinguished Professor, Colorado State University, Fort Collins, Colo