The Science of Fear:Why We Fear the Things We Shouldn’t by Daniel Gardner

Posted on June 28, 2009 by skeptvet

The Science of Fear: Why We Fear the Things We Shouldn’t-and Put Ourselves in Greater Danger by Daniel Gardner does an outstanding job of explaining and supporting the argument that our ability to assess risks is fundamentally flawed.

The basic thesis is that our brains developed in an evolutionary context that selected for heuristics, quick and dirty methods of assessing situations and establishing guidelines for responding to the environment. These heuristics are hardwired into our brains (though Gardner refers to them collectively as Gut), and we tend to use them to rapidly judge how serious a potential risk is. Our higher reasoning abilities (which Gardner labels Head) can moderate these snap judgments by applying relevant facts and analysis, but more often our conscious reasoning merely manufactures rationalizations for what we’ve already decided.

The psychological literature on heuristics is vast, and though he uses shortcut labels such as Gut and Head, Gardner does a good job of defining and illustrating specific heuristics and tracing their discovery and the evidence for them. He then delves into factors that tend to prevent Head from doing a good job of moderating our emotional risk assessments. Inadequate education and familiarity with the relevant facts and with statistics, the influence of others’ opinions on our own, and the manipulation of our judgments through the media by government, industry, and lobbies, all of which use fear as a way to raise money and consciousness regardless of the statistical realities of the dangers they want us to care about.

He does an especially thorough job tracing the history of how unjustified popular fears of toxic chemicals in the environment and terrorism emerged and were promoted by the deliberate effort of those who cared more about influencing people’s behavior than about truth. I routinely have to disabuse people of the notion that their tap water or perfume or commercial dog food contains mysterious but horrible toxins responsible for their pet’s cancer. Gardner provides overwhelming evidence to show that environmental toxins are a negligible source of cancer, and yet we fear them out of proportion to their real danger. This leads us to underestimate the importance of much more significant risk factors such as age and obesity.

Gardner ends with what is for me the most salient chapter, entitled There’s Never Been a Better Time to Be Alive. Humans, and our pets, routinely live longer, healthier lives than at any time in history, and yet we are beset with anxieties about the food we eat, the water we drink, the air we breathe, the vaccines that protect us from the infectious we used to die of, and so many other sources of danger that we would be better off paying far less attention to. It is sad more than ironic that our ability to enjoy the unprecedented well-being our era provides is handicapped by our innate risk evaluation apparatus, which is still using rules that may have worked well enough on the savannah but which simply cannot cope with the subtleties and complexities of the modern world. Gardner provides some glimpses of hope, showing that while we cannot eliminate the errors in our risk assessments, we can moderate them significantly by virtue of deliberate, and difficult, application of thought and analysis.

From the point of view of scientific medicine, this book provides yet more evidence of the unreliability of our clinical judgments and intuitions compared with well-designed and conducted research. Science-based medicine acknowledges that we must have the courage and intellectual integrity to accept the inadequacy of our own judgments, of how things seem when confronted with clear evidence that they are wrong. CAM, in contrast, relies inherently on anecdote, tradition, and subjective evaluation for validation. And sadly, as unreliable as these clearly are, they are emotionally compelling. A nice companion to this book is Robert Burton’s On Being Certain: Believing You Are Right Even When You’re Not, which looks at the mechanisms of how we come to feel we know the truth of something. This feeling, like our assessment of truth and risk, is established at a level of thought we are not consciously aware of and then rationalized, often through obvious confabulation, by the conscious mind. The feeling of certain gets applied to our gut-level evaluation of the risk or benefit of something, and it then takes more effort than most of us are able or willing to make to discard the heuristic judgment in favor of the rational, and more likely correct one. But a commitment to doing the best for our pets requires that we try to make this effort so that we can provide them with the best care.

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From Science-Based Medicine Blog-Death and Rebirth of Vitalism

Posted on June 25, 2009 by skeptvet

Peter Lipsom has written a concise and insightful post at the Science-Based Medicine Blog, entitled The Death and Rebirth of Vitalism. It illustrates why the underlying philosophical position of faith-based medicine is unteneable. Magical entities, such as Ch’i in acupuncture, Innate Intelligence in chiropractic, Water Memory in homeopathy and so on, are required by CAM practices that cannot demonstrate plausible rationales by mainstream scientific methods. This contrasts with the Methodological Naturalism required by science, and the true philosophical naturalism and materialism many scientist accept as the truth about the nature of the universe.

As the comments that follow the post illustrate, pointing out the intellectual bankruptcy of the philosophy behind most CAM approaches can lead to resistence against science-based medicine even among scientists and people not otherwise sympathetic to CAM. This is at least partly because looking at the underlying philosophical and epistemelogical distinctions between science-based and faith-based medicine can lead to awkward questions about other faith-based beliefs.

The human mind is miraculous in its ability to hold contradictory ideas at the same time, so many scientists can go about their lives practicing methodological naturalism while believing in the eternal soul, reincarnation, or other non-material entities without trouble, so long as the conflict isn’t shoved in their faces. When it is, some attempt to work out acceptable philosophical compromises, such as Stephen Jay Gould’s Non-Overlapping Magisteria approach. Others simply choose faith over reason and most simply decide not to dwell on the issue. A few, think and read and meditate deeply about the controversy and elect to try and extend their professional naturalism into all areas of their lives. As far as I’m concerned, these are all fair and legitimate responses to a tough question.

But what is not legitimate is when the challenge to faith in areas outside of science is so threatening that scientists choose to let go of their methodological naturalism and embrace faith-based medicine uncritically. Not everyone cares to conduct difficult and complex investigations into the philosophical underpinnings of theri work or their personal life, and this isn’t by any means a requirement for a productive life in science or medicine. I happen to think it can enrich anyone’s life and work, but that may just be my personal intellectual tastes. However, when it comes to the material world, which includes the bodies and minds of our patients and the tools with which we treat them, there are right and wrong answers. Vitalism may stumble on the right answers by accident from time to time, but science and methodological nauralism consistently get the answers right far more often. To ignore this and cling to faith-based medical practices simply to avoid uncomfortable questions about other deeply held faith-based beliefs is intellectually dishonest and not in the best interests of our patients.

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Veterinary Vaccines-Fact and Fiction

Posted on June 24, 2009 by skeptvet

What Are Vaccines?
The principle behind vaccination is that small amounts of weakened or killed organisms that normally cause disease, or even just pieces of these organisms, are given to an animal. This stimulates the immune system to generate a protective immune response without an actual infection or illness.

The first experiments with vaccination in dogs were conducted by Louis Pasteur in 1884, but reliably safe and effective vaccinations for most disease were not routinely available until the 1950s or later. Since vaccination became commonplace, the incidence of rabies, distemper, parvovirus, and many other infectious diseases has decreased dramatically. Along with improvements in nutrition and the development of antibiotics, vaccines have been among the most successful medical interventions for reducing disease, suffering, and death in companion animals.

But like all effective medical treatments, vaccines are not without risks, and recently there has been an increase in concern about their safety. Fortunately, there has also been a great deal of research into the benefits and risks of vaccination, and this information can help veterinarians and pet owners to make appropriate decisions about the best way to safeguard their pets’ health.

Why Vaccinate?
There are many infectious diseases that affect dogs and cats. Some cause severe, life-threatening illness. Some cause mild symptoms that can resolve spontaneously or persist for years. And some, such as rabies, can cause disease in humans as well as our pets.

The most obvious benefit of vaccination is preventing illness in the individual given the vaccine. This is especially clear with vaccines that are highly effective at preventing potentially fatal infections, such as canine distemper, canine parvovirus, and feline panleukopenia. Even those vaccines that do not prevent illness can reduce the severity of symptoms, as in the cases of several upper respiratory viruses in cats.

A less well-know but very important benefit of vaccination is to prevent epidemics in a population of animals, through what is called herd immunity. If a large number of individuals are protected by vaccination, there are not enough susceptible animals to allow a disease to spread, and so even unvaccinated individuals are protected from infection. When vaccination rates drop, however, then a few isolated cases can turn into a widespread epidemic.

There have recently been outbreaks of measles and haemophilus influenza B among humans as a result of fewer people in some areas getting vaccinated for these diseases. And in 1994-1995 there was an epidemic of canine distemper in Finland, where the disease had previously been eliminated, largely because too few dogs were adequately vaccinated.

The proportion of the population that must be vaccinated for herd immunity to work depends on the prevalence of the disease, the effectiveness of the vaccine, and other factors, but in most cases more than 90% of individuals must be vaccinated for those who are not to be protected. So if even a few individuals do no receive adequate vaccination, an epidemic can potentially develop.

Finally, vaccination of pets can be important for the health of their owners and other humans. Human cases of rabies due to dog bites, which is nearly always fatal, were once a serious public health problem in the United States. Widespread vaccination of dogs has eliminated this threat, though it is still a serious risk for people, especially children, in countries where such vaccination is not available or utilized.

Do They Work?
For many serious diseases, vaccination is very effective. There is some variation between vaccines, but the efficacy for vaccination against canine distemper, canine parvovirus, rabies, feline panleukopenia, and feline leukemia is excellent, in some cases close to 100%. Other vaccines, such as those for feline herpes virus and feline calicivirus, may not prevent infection but may markedly reduce the symptoms the infected pet suffers. However, there are some vaccines that are considered only poorly effective and others for which not enough information exists to determine how well they work.

As already mentioned, herd immunity depends to some extent on how common the disease organism is in the environment, how effective the vaccine is, and what percentage of the population is vaccinated. Even for vaccines with weak efficacy, if most animals are vaccinated then epidemics are less likely. And even when a vaccine is very effective, if many unvaccinated individuals are present to spread the disease, epidemics can develop.

What, When, How Often?
When many of the common vaccines were introduced decades ago, there was limited information on how effectively they protected animals from disease and for how long. The common practice was to give vaccines for many different diseases routinely every year. Significant improvements in our understanding of how vaccination works to prevent disease has led to widespread abandonment of this practice. The precise vaccines to be given, when, and how often can only be determined on an individual basis, considering the exposure of the patient to specific diseases, the effectiveness and risks of available vaccines, and many other factors. Some general principles, however, are applicable to all individuals.

Puppies and kittens that nurse usually receive antibodies from their mothers. These antibodies offer some protection from infectious diseases, though how much protection and for which diseases depends on many variables and is very difficult to predict. These maternal antibodies, however, also interfere with the action of vaccines. As puppies and kittens mature, they gradually lose their maternal antibodies and, if vaccinated, develop their own. For most individuals and most diseases, maternal antibodies begin to decrease by 6-8 weeks of age and are effectively gone by 14-16 weeks of age. As the level of maternal antibodies decreases, the young animals are at more and more risk for contracting infections until they have produced sufficient protective antibodies of their own.

For this reason, young animals must receive a series of vaccinations between 6 and 16 weeks of age. Because it cannot be determined exactly how much protection each individual has from nursing or how long that protection lasts, a series approach to vaccination maximizes the development of the patient’s own antibodies and minimizes the risk of gaps in protection as the maternal antibody levels decline.

For adult animals, the vaccines that will best protect them depend on individual circumstances. Current recommendations divide vaccines into core and non-core categories. Core vaccines are those that protect against organisms which cause severe disease, are easily transmitted between animals, are widespread in the environment, and for which the vaccines are recognized as safe and highly effective. Non-core vaccines are those used for organisms that cause mild self-limiting disease, are not widespread or easily transmitted, or for which the vaccines are not highly effective or carry unacceptable risks. Non-core vaccines are still appropriate to use if warranted by circumstances, but unlike core vaccines are not generally recommended for all pets
Finally, a few vaccines are generally not recommended at all due to uncertainty about their safety or efficacy or other concerns.

It is generally recommended all animals receive core vaccines at regular intervals and only receive non-core vaccines if the individual’s circumstances suggest the benefit outweighs the risks. For dogs, most veterinarians consider core vaccines to be those against canine distemper, parvovirus, hepatitis, and rabies. For cats, feline panleukopenia, herpes virus, and calicivirus vaccines are generally consider core vaccines. There is some debate about whether rabies and feline leukemia vaccines should be considered core vaccines for cats, and this depends mostly on a given cat’s likelihood of exposure, age, and the local rabies vaccination laws.

How often to give vaccines to adult animals is a topic of vigorous debate. Differences in individual immune function, in vaccine efficacy and safety, in regional risk of exposure to specific diseases, in individual or breed predisposition to diseases and response to vaccines, and many other factors make it nearly impossible to make definitive and universal statements about how long a vaccine will protect a given patient. A broad consensus exists among veterinarians and researchers that the initial puppy or kitten series of core vaccinations and a booster one year later is appropriate for almost all animals. There is strong evidence that most core vaccines will provide adequate protection for most individuals if given at most every 3 years, and for some diseases protection likely lasts much longer. However, there is insufficient evidence for detailed and universal guidelines for most vaccines.

There is little research on vaccines in geriatric animals. Older pets do respond to vaccines with an appropriate increase in immunity, and they do not seem to be at an increased risk of dverse reactions from vaccines. There is no sound evidence to suggest that vaccination should be stopped at any particular age.

A general principle of medicine is that the benefit of a treatment should exceed the risk, so much of the discussion about how often to vaccinate and for which diseases centers on what is know about the risks of vaccination.

Are They Safe?
Like any potent medical therapy, vaccines can have unintended effects. Since vaccines are commonly given, often multiple times over many years, it can be difficult to decide if an illness is related to previous vaccination. In humans, there has been much concern about vaccination being responsible for autism in children, since the disease tends to emerge at about the time most children are vaccinated. Only after years of extensive research in thousands of children throughout the developed world has this theory been convincingly disproven. High quality research on this large a scale is rarely possible in veterinary medicine.

However, some good quality studies have been done to determine what adverse effects vaccines might cause, and how common and serious these are. Estimates vary, largely because it is often impossible to determine what the total population of dogs or cats is, what percentage of these have been vaccinated when and for what, and to gather other information necessary to accurately determine how common vaccine reactions really are. On the high end, estimates of total adverse vaccine reactions, provided by manufacturers based on pre-clinical testing, are on the order of 100 reactions per 10,000 vaccine doses given. Numbers based on research in actual pet populations are much lower, ranging from less than 1 reaction per 10,000 vaccines given up to 13 reactions per 10,000 doses given in dogs and 20 per 10,000 doses given in cats.

The most common by far are local or systemic hypersensitivity reactions, usually called allergic reactions. These account for 30-60% of adverse vaccine reactions. The vast majority of these reactions that are seen by a veterinarian resolve spontaneously or with minimal medical treatments. Many localized allergic reactions are thought to resolve without ever being noticed by the owner or reported to a veterinarian.

The risk of allergic reactions is not the same for all pets. Smaller dogs are at greater risk than larger dogs, and the risk increases the more vaccines are given at one time. Some research suggests certain breeds may be at higher risk than others, but other studies do not support this.

More serious adverse reactions are much rarer. A disease in which the immune system attacks the patient’s own red blood cells (IMHA) has been reported in one study to be associated with vaccination at a rate of 0.01 reactions per 10,000 doses, though a more recent study of the same disease found no association with vaccination. Other autoimmune diseases have been reported in specific breeds (such as hypertrophic osteodystrophy after canine distemper vaccine in Weimeraners and localized vasculitis in Dachshunds), but these are uncommon to rare and linked with specific genetic predispositions in affected dogs. It is also important to remember that these diseases can also be triggered by the very infections vaccines are used to prevent as well as medications, natural substances in food and in the environment, and anything that stimulates a response in the immune system of a predisposed animal.

The most widely known adverse vaccine reaction in animals is a rare type of cancer in cats known as Vaccine Associated Sarcoma (VAS). Identified by careful research in the early 1990s, this tumor has been linked to specific vaccines for rabies and feline leukemia. Similar tumors can occur spontaneously or in response to trauma, foreign bodies, local infections, and other things that stimulate the immune system. However, the risk of VAS is significantly increased by these vaccines, and it is suspected that the reason is certain ingredients, such as aluminum, that were added to the vaccines to increase their stimulation of an immune response. Estimates vary, but the most reliable figures suggest VAS occurs at a rate of 0.3-2 tumors per 10,000 vaccine doses given.

The discovery of this tumor stimulated much concern about the safety of vaccinations. While it is quite rare, great efforts have been made to reduce the incidence of VAS by developing new vaccines and researching the safest way to use these vaccines to protect cats from infectious disease while minimize such reactions. The debate and research has even spread beyond feline leukemia and rabies and stimulated a significant change in vaccination practices generally for both dogs and cats.

Finally, it is vital not to forget that the risks of vaccination must be considered in light of the benefits. For most core vaccines, the diseases they protect against represent a far greater threat to the health of our pets than the vaccines.

Vaccine Myths
While careful evaluation of the risks and benefits of vaccination, and cautious and thoughtful use of this potent medical tool, is absolutely appropriate, irrational fear of vaccines has unfortunately led to the spread of many myths about them. Some of the concerns raised about vaccines used in humans have been extended to companion animal vaccination, despite the evidence that many of these concerns are unfounded. And it has become all too common to identify vaccination as a possible, or even probable cause for any disease that is not yet completely understood. While unknown and unpredictable risks are always possible, careful scientific research has discovered even such rare adverse effects as Vaccine Associated Sarcomas, and many of the purported negative effects of vaccines are merely wild speculations with no basis in fact.

The most common myth about vaccines is that they are not necessary since the diseases they protect against are rare. The diseases for which we have core vaccines in dogs and cats all continue to exist in the population as a threat to unvaccinated individuals. And in cases where vaccine rates have dropped due to this misconception, epidemics of some of these diseases have occurred.

Another common concern are the immune system diseases caused by vaccines. Though auto-immune diseases such as IMHA may be associated with vaccination, this has not been conclusively demonstrated. And if vaccines do precipitate such diseases, so do infectious organisms, natural substances in food, and many other possible environmental factors. These conditions are uncommon, and any risk of them posed by vaccination is undoubtedly outweighed by the protection the vaccines offer against serious infectious diseases.

Some vaccinated animals have been shown to have antibodies against normal proteins in their own bodies, including the thyroid gland and the kidneys, and this has stimulated speculation that diseases in these organs may be the result of vaccination. However, the relationship between vaccination and such antibody formation is inconsistent, and no actual immune-mediated disease has ever been shown to result from the presence of vaccine-induced auto-antibodies.

Much publicity has been generated by concerns over “toxins” in vaccines. Thimerosal, aluminum, formaldehyde, anti-freeze, and many other substances have been claimed to be present in vaccines and to be harmful to vaccinated people or animals. Some of these substances are present in minute quantities in vaccines, though others are not. The primary misconception that creates unjustified fear about these ingredients is the notion that substances are inherently either toxic or safe. Water and oxygen can be poisonous, even fatal in high enough amounts even though they are vital for life. And while large amounts of some vaccine ingredients can be dangerous, the minute quantities in vaccines have never been shown to be harmful.

Preservative such as thimerosal and formaldehyde prevent bacterial and fungal contamination of vaccines, and research in humans has shown they do not cause harm at the amounts given in vaccines. Aluminum adjuvant has not been associated with significant risk in humans. In cats, aluminum is believed to increase the risk of VAS, and non-adjuvanted vaccines are now recommended in this species.

Some people have expressed concern over the number of vaccines given in the puppy or kitten series, or over the lifetime of the pet, and have put forward the notion that so many vaccine antigens (the part of the disease-causing organism that the immune system reacts to) may “overload” the immune system, causing health problems. However, the number of foreign antigens animals are exposed to in vaccines is far less than what they encounter in the course of everyday life. We and our pets ingest and inhale antigens continuously, and we are exposed to more through wounds, insect bites, and many other sources. The relative contribution of vaccines to the total antigen exposure of any individual is miniscule. And the capacity of the immune system to generate a response to possible disease-causing organisms is so vast that even the extensive vaccination schedule recommended for children has been calculated to require only about 0.01% of this capacity.

It is commonly supposed that vaccines should be dosed by body weight the way most drugs are in veterinary patients. This is a misconception. While most drugs work by being distributed throughout the body and acting in proportion to their concentration in the blood or tissues, vaccines stimulate the immune system locally where they are administered. The Minimum Immunizing Dose (MID) is the amount of antigen necessary to stimulate a protective immune response. This varies by species and vaccine, but it has little relationship to body size. Horses only receive twice as much rabies vaccine as dogs, and elephants only twice as much as horses. The difference in size between individuals within a species is too small to affect the MID, and if only partial doses of vaccine are given there is a real risk on not triggering an adequate response to protect the patient.

Finally, there has been some talk of a vague, generalized illness attributed to vaccination and sometimes referred to as “vaccinosis.” There is no consistent definition of this supposed illness, but it is generally described with a series of anecdotes about animals that were vaccinated and became ill sometime afterwards, with no explanation of why the vaccine should be considered responsible for the illness. There is no evidence that “vaccinosis” is a real clinical entity or that the practice of blaming any illness of unknown cause on vaccines is justified.

A large-scale study of over 4000 dogs completed by the Animal Health trust in the UK found no association between vaccination and any specific illness, or ill-health in general, in the 3 months following the vaccination. Careful and controlled research is needed to document any adverse reaction to vaccines, and without such research there is no basis for concluding that vaccines cause disease beyond the uncommon, and rarely serious reactions already identified.

Alternatives to Vaccination?
The most commonly chosen alternative to vaccination is simply to not vaccinate. Unfortunately, this replaces the very small risks from vaccines with a much greater risk of disease for the unprotected individual and for other animals and even humans. While it is true that natural exposure to infectious organisms can stimulate a protective immunity, this comes with a risk of disease that is much more dangerous than the adverse effects of vaccines.

It has been suggested that proper nutrition in general, or special diets and dietary restrictions, can prevent disease and make vaccination unnecessary. While the immune system does function poorly in malnourished animals, those individuals who are fed adequate amounts of a balanced diet and are in good general health have normal immune function. There is no evidence that special diets or dietary limitations can improve on this normal function, and diet is certainly no substitute for appropriate vaccination.

Some alternative products claim to provide protection from disease without the risks of vaccines. The most common of these is the homeopathic nosode. Nosodes are prepared by extreme dilution of blood, urine, pus, or some other substance associated with the infection the preparation is supposed to prevent. Like all homeopathic preparations, nosodes do not contain any of the original ingredients due to the extensive dilution, so they consist only of the vehicle used, usually water or alcohol. Despite the lack of a plausible scientific rationale behind nosodes, some clinical studies of their effectiveness have been done, and these have shown them to be ineffective at preventing canine parvovirus and other infectious diseases.

Finally, blood antibody titers are sometimes recommended as an alternative to vaccination. This is a complex subject, and it is not possible to make definitive, universal recommendations about when titer testing is helpful. For some diseases, such as canine parvovirus, rabies, and feline panleukopenia, high antibody titer levels have been shown to reliably predict resistance to infection. However, due to other elements of the immune system which titers do not measure, animals with low titers to these diseases may still be protected from infection.

For other diseases, titers do not reliably predict whether the patient is resistant to the disease or not. And the predictive value of antibody levels also depends on how common the disease is in the population, so for an uncommon disease a negative titer is more likely to be an error, which makes deciding which individuals need vaccination based on their titer unreliable. Titers are useful in certain circumstances, but they are not appropriate as a routine alternative to vaccination for the general population.

Summary

? Vaccination is an important tool that has reduced the risk and harm of infectious disease dramatically in companion animals.

? While they vary in their efficacy, most commonly used vaccines are highly effective at preventing infection or reducing the symptoms of disease.

? Puppies and kittens need a series of vaccinations between 6 and 16 weeks to develop their own protective immunity as the maternal antibodies they get from nursing disappear.

? Which vaccines need to be given to adult animals, and how often, should be decided on the basis of unique individual circumstances and risk factors.

? Vaccines are generally very safe, but some adverse effects do occur. These are uncommon and usually easily treated, but more serious effects are possible, and the benefits of vaccination should always be weighed against the risks for each patient.

? The fears that vaccines contain harmful toxins, that they overwhelm the immune system, or that they routinely cause serious illness are unfounded and not supported by any real evidence.

References and More Information
American Animal Hospital Association Canine Vaccine Task Force. Canine vaccine guidelines (rev). 2006. Available at http://secure.aahanet.org/eweb/dynamicpage.aspx?site=resources&webcode=CanineVaccineGuidelines .

American Veterinary Medical Association. What you should know about vaccinations. 2008. Available at www.avma.org .

Day, M.J. Vaccine side effects: Fact and fiction. Vet Microbiol 2006; 117:51-58.

De Verdier K, Ohagen P, Alenius S. No effect of a homeopathic preparation on neonatal calf diarrhoea in a randomised double-blind, placebo-controlled clinical trial. Acta Vet Scand 2003; 44:97-101.

Edwards, D.S., Henley, W.E., Wood, J.L. Vaccination and ill-health in dogs: a lack of temporal association and evidence of equivalence. Animal Health Trust 2004. Available at http://www.future-of-vaccination.co.uk/animal-health-survey.asp .

Ek-Kommonen, C., et al. Outbreak of canine distemper in vaccinated dogs in Finland. Vet Rec 1997; 141:380-383.

Feline Vaccine Advisory Panel, American Association of Feline Practitioners. JAVMA 2006; 229:1405-1441.

Frana, T.S., Clough, N.E., Gatewood, D.M., Rupprecht, C.E. Postmarketing surveillance of rabies vaccines for dogs to evaluate safety and efficacy. JAVMA 2008; 232:1000-1002.

Klingborg, D.J., et al AVMA Council on Biologic and Therapeutic Agents’ report on cat and dog vaccines. JAVMA 2002; 221:1401-1407.

National Office of Animal Health. Vaccination of companion animals: Briefing Document No. 10. Available at www.noah.co.uk .

Gobar, G.M, Kass, P.H. World wide web survey of vaccination practices, postvaccinal reactions, and vaccine site-associated sarcomas in cats. JAVMA 220; 1477-1482

Grosenbaugh, D.A., et al. Comparison of the safety and efficacy of a recombinant feline leukemia virus (FeLV) vaccine delivered transdermally and an inactivated FeLV vaccine delivered subcutaneously. Vet Ther 2004; 5:258-262.

Holmes MA, Cockcroft PD, Booth CE, Heath MF. Controlled clinical trial of the effect of a homoeopathic nosode on the somatic cell counts in the milk of clinically normal dairy cows. Vet Rec 2005; 156:565-567.

Larson L., Wynn S., and Schultz R.D. A Canine Parvovirus Nosode Study. Proceedings of the Second Annual Midwest Holistic Veterinary Conference 1996.

Legendre, A.M., et al. Comparison of the efficacy of three commercial feline leukemia virus vaccines in a natural challenge exposure. JAVMA 1991; 199:1456-1462.

Moore, G.E. Vaccine reactions today and tomorrow: When vaccines do too much. Proceedings of the American College of Veterinary Internal Medicine 2003.

Moore, G.E. A perspective on vaccine guidelines and titer tests for dogs. JAVMA 2004; 224:200-203.

Moore, G.E., et al. Adverse events diagnosed within three days of vaccine administration in dogs. JAVMA 2005; 227:1102-1108.

Moore, G.E., et al. Adverse events after vaccine administration in cats: 2,560 cases (2002-2005). JAVMA 2007; 231:94-100.

Offit, P.A., Jew, R. K. Addressing parents’ concerns: Do vaccines contain harmful preservatives, adjuvants, additives, or residuals? Pediatrics 2003; 112:1394-1401.

Offit, P.A., Bell, L. M. Vaccine Concerns. Chapter 15 of Vaccines: What You Should Know 2003. Available at www.immunize.org .

Rikula, U. K. Canine distemper in Finland- Vaccination and epidemiology. Academic dissertation 2008. Available at http://www.evira.fi/uploads/WebShopFiles/1207123242400.pdf .

Roush, S.W, Murphy, T.V. Historical comparisons of morbidity and mortality for vaccine-preventable diseases in the United States. JAMA 2007; 298:2155-2163.

Scott-Moncrieff, J.C., et al. Evaluation of antithyroglobulin antibodies after routine vaccination in pet and research dogs. JAVMA 2002; 221:515-521.

Veterinary Prducts Committee Working Group on Feline and Canine Vaccination, Dept. for Environment, Food & Rural Affairs 2001. Available at http://www.noah.co.uk/papers/vpc-catdogvetsurv.pdf .

Wolf, A.M. Vaccines, viruses, vaccinosarcoma-Truth or fiction. ProceedingsAtlantic Coast Veterinary Conference 2002.

© Brennen McKenzie, 2009
http://www.skeptvet.com
http://skeptvet.com/Blog

Posted in Vaccines | 29 Comments

Government Fails to Protect People from Harmful CAM

Posted on June 23, 2009 by skeptvet

A healthy women, told by her chiropractor she needed her subluxations treated by forceful manipulation of her neck to “improve her health and wellness” ended up a quadraplegic. She and others hurt by chiropractors in Canada have filed a class-action lawsuit, not only against the chiropractors but against the state government. The government, of course, is trying to get itself out of the lawsuit, which alleges that it bears some responsibility for the harm done to healthy people by chiropractors.

While it is no surprise to anyone that governments set health policy based on money and influence rather than science, it has always disappointed me how easily ineffective, unproven, and even potentially dangerous medical treatments get the imprimatur of the state. When I begin to tell people about the lack of evidence for benefit from chiropractic manipulations, the second objection they make after reporting some anecdotes and testimonials is that it is licensed by the government so how could it not work? It’s difficult to explain to them simply why money and influence trumps science, and why our faith in government regulation of medicine is not justified when it comes to CAM. By not insisting on real evidence of safety and efficacy for all medical therapies, government not only contributes to the harm CAM does to its citizens, but it undermines its own credibility as guardian of the public health.

A lawsuit like this, though I doubt it will be successful, makes a stark and important point. People rely on their government to protect them from harmful and useless treatments when they are suffering and vulnerable to peddlers of snake oil. Because mainstream medicine has been so successful in the last 200 years, people are accustomed to trusting that anyone who calls themselves a doctor knows what they are about. Otherwise, wouldn’t the government step in and stop them? Unfortunately, the economic power of the CAM lobby and the zeal of true believers in government, like our own Sen. Tom Harkin here in the U.S., interfere with the mechanisms the government would normally use to protect people from dangerous treatments.

Ironically, mainstream scientific medicine, and even the quintessential bogeyman of Big Pharma, is heavily scrutinized and regulated, and it is a costly and time-consuming process to get a treatment that actually works approved. And when uncommon problems are identified, by virtue of post-marketing surveillance mechanisms the government requires, instead of seeing this as evidence for the success of the science and the system, CAM proponents use it as more evidence that their own therapies are safer alternatives.

Undoubtedly, less harm is reported subsequent to CAM treatments simply because no one is watching or keeping track. What’s The Harm, Victims of Chiropractic Abuse, and other private groups try to warn people of the dangers, but many of the dangers are not even known, and such small advocacy groups cannot match the resources and influence of government. I hope the government of Alberta is made to acknowledge it has abdicated its responsibility to its citizens to protect them from dangerous medical treatments, though I am not optimistic. And here in the U.S., President Obama has promised to see that science resumes “it’s rightful place” in the setting of public policy. He will undoubtedly have a very hard time keeping that promise. But for the sake of all those who the government might save from the harm of untested treatments, I hope he can.

 

Posted in Law, Regulation, and Politics | 2 Comments

The Ethics of the Placebo Effect

Posted on June 16, 2009 by skeptvet

There are many reasons why therapies which don’t actually have a physical effect on a disease may appear to work anyway (an extensive list of which can be found under Can We Trust Clinical Experience? at my website). One of the best known, and misunderstood, is the so-called Placebo Effect.

 

Though this is generally used to mean any positive effect of a treatment that isn’t actually affecting the underlying disease, it really should apply more narrowly to perception-mediated non-specific effects of a treatment. In humans subjective perception of discomfort (pain, nausea, anxiety, etc) often improves with any treatment, and this seems to be largely due to the effects of expectation, diversion of attention, and classical conditioning. Objectively measurable physical parameters can be altered by the placebo effect, but disease progression and outcome are not.

 

In animals, the influence of expectation and diversion of attention do not seem to play a role in the placebo effect, but nonspecific effects of ineffectual treatments are seen. One possible reason for this is classical conditioning. Dogs exposed to food and a ringing bell can be conditioned not only to salivate and look for food but to secrete stomach acid when the bell is rung. Animals repeatedly given insulin injections, which lower blood sugar, can then manifest a decrease in blood sugar when given a saline injection. So the experience of feeling better after receiving true treatment for disease in the past could possibly condition a mild, transient improvement from the same treatment environment in the absence of a truly effective therapy.

 

There are other possible explanations for a placebo-like effect in veterinary patients (stress hormone release associated with the vet visit, changes in owner management during a period of concern, etc). Probably the most significant, however, is what I call the “placebo effect by proxy.” Owners have a strong desire to see their pets get better. They also have a desire see the worry and expense of a vet visit validated by improvement. Confirmation bias, cognitive dissonance, and old-fashioned wishful thinking can all make therapies initially seem to work even when they are doing nothing. And in cases where other factors such as regression to the mean of chronic symptoms, spontaneous resolution of disease, and misdiagnosis lead to a true resolution of the complaint, useless therapies may seem to work, the patient will get better, the owner will be happy, and the vet will get the credit. So what’s wrong with that?

 

Well, for one thing taking advantage of a direct or proxy placebo effect requires deception. The patient or client must believe they are being given a real therapy. In fact studies have shown that the more confidence with which a doctor presents a placebo to a patient, the more effect it has.

 

Introducing deliberate deception into the medical relationship strikes me as an ethical and practical quagmire. As a vet, people trust me to do painful, costly things they don’t always fully understand to their family members. This trust requires that I be honest with them, and there is no effective way to do this and still utilize therapies I believe to be ineffective. At best, I could say, “Treatment X has not been proven to be beneficial but anecdotally some people have reported a positive response…” Such a weak presentation would likely diminish the desired non-specific effects while not really solving the ethical problem.

 

In the veterinary setting, the placebo is likely working much better on the owner than the patient. So while I might get some undeserved credit for a bogus treatment, the patient is still suffering. And since not all placebos are without risks (such as the still apparently common practice of prescribing antibiotics for viral infections), utilizing them can even present a small risk of doing harm for no true benefit in terms of the disease, regardless of whether the patient or client perceives a benefit.

 

I once denied a client a prescription for antibiotics for their cat, who had bloody urine. The particular circumstances indicated the cat had a vanishingly small chance of having a bacterial infection (no more than 2% in one study), while the incidence of vomiting, anorexia, and diarrhea from the antibiotic was much higher (about 10-15%). The clinical signs in such cases usually go away by themselves in about 7 days. The client was irate and went to my boss, who gave her what she wanted.

 

When I challenged him for doing so, I pointed out that he would get credit for solving the problem when what he had done only satisfied the owner, did nothing for the pet, and exposed the patient to an unnecessary risk. He felt that if the pet got better, the client was happy, and he got the credit it was a win for everybody, and he couldn’t see any ethical dilemma. He was also a much older doctor who had trained at a time when human medicine still followed the paternalistic model, doing what the doctor thought best without regard for the patient’s wishes. That model has been rejected by mainstream human medicine, and it has not place in veterinary medicine either.

 

It is common for vets and doctors who are not believers in alternative therapies to utilize them anyway because they make clients or patients happy. These providers generally rationalize this by saying that the risk is low (which it generally is) and that a true benefit is at least possible (which it often is not). However, they fail to include in this calculation the risks, and the raw ethical problem, of deliberately deceiving the client or patient. And they ignore the very real practical problem of encouraging belief in ineffective or unproven therapies and the epistemological and philosophical paradigms that often accompany them, and which are generally very anti-scientific.

 

While there is always some uncertainty about the risks and benefits of any treatment in a given clinical situation, and while honesty does not always require a lawyerly detailing of these that creates pointless anxiety, using clearly disproven approaches, and even implausible treatments that have not been thoroughly tested, requires us to violate the trust our clients and patients give us for a superficial and transient benefit, which in the veterinary setting does not even apply to the actual patient. It may be more difficult to deserve this trust with sometimes uncomfortable honesty, but I am convinced this is the right path to take, ethically and practically.

Posted in General | 3 Comments

Trick or Treatment-The Undeniable Facts About Alternative Medicine

Posted on June 11, 2009 by skeptvet

Trick or Treatment: The Undeniable Facts About Alternative Medicine is one of the best-written and most accessible books on the topic available. It is written by Edzard Ernst and Simon Singh.

Ernst is a medical doctor and homeopath with extensive experience practicing and studying complementary and alternative medicine (CAM). He is an ideal author for this book because he combines a true open-mindedness and personal experience with alternative therapies in practice with a rigorous adherence to the principles of evidence-based, scientific medicine. He cannot be tarnished with the nonsense so often leveled at critics of CAM that he is motivated only to maintain the supremacy of some corporate medical establishment, that he is intellectually closed-minded and blind to the potential of therapies not arising from the establishment, and so on. He clearly cares about the wel-being of his patients and believes deeply that he can best help them only by knowing the truth about the therapies available.

Simon Singh is a journalist and science writer with a gift for language and an admirable commitment to truth, even when it is unpopular or dangerous. Right now he is being persecuted by the British Chiropractic Association, with the help of Britain’s bizarre libel laws, for statements The Guardian newspaper. While it is difficult to imagine for those of us accustomed to U.S. libel law, in Britain it is possible to be successfully sued for making truthful statements, backed by evidence, about scientific controversies. He has courageously stood alone, at great personal and economic cost, to support the right to speak the truth about scientific questions.

Trick or Treatment begins with an introduction to the history and basic principles of the scientific method and evidence-based medicine. But rather than a dry, technical account, the authors make use of a technique all too common among CAM proponents and all too often shunned by science writers. They illustrate the principles with vivid personal narratives. The history of bloodletting as a medical therapy is rightly used as a prime example of why science is superior to experience, authority, and anecdote as a way of judging the truth about medical practices. And the story of George Washington, slowly bled to death by his doctors, is a powerful example of how tragically misguided the faith-based approach to medicine is.

There are then a series of chapters examining in detail Acupuncture, Homeopathy, Chiropractic, and Herbal Medicine. These offer some brief historical perspectives and a review of the evidence that is clear and comprehensive but not overly technical and quite accessible to the general reader. While I could certainly find fault here or there with specific points, the overall assessment is clear, cogent, and well-supported.

Ernst is a dedicated proponent of evidence-based medicine. I would argue that this approach is far better than the faith-based medicine most CAM proponents practice, but it does have some flaws. For one, it tends to view all ideas, no matter how wacky, as equally deserving of extensive clinical research to determine if they are safe or effective therapies. I agree with the arguments of science-based medicine that given the limitations of resources and the practical realities of research, selecting which approaches to investigate rigorously should be a careful and deliberate process that takes into account the scientific plausibility of the idea. Faith healing and non-steroidal anti-inflammatory drugs do not have an equal probability of being useful treatments based on the context of well-established scientific knowledge, and spending talent and money on both equally is ludicrous.

Nevertheless, I cannot fault the intellectual or scientific rigor of Ernst and Singh’s summaries, and I cannot laud highly enough the quality and accessibility of the writing. While I am even more impressed by the thoroughness and rigor of a similar recent book (Snake Oil Science: The Truth About Complementary and Alternative Medicine by R. Barker Bausell) I would be far more likely to recommend Ernst and Singh’s book to a lay reader. They make their case eloquently and in such a way that the sense of what they are saying is evident even to those skeptical of the general superiority of science as a way of knowing the truth.

A number of other CAM approaches are covered in brief, 1-page summaries, which are useful quick references but not sufficiently thorough to be used as definitive assessments of these approaches.

The final chapter, Does the Truth Matter, is one of the best. It makes very clear the economic cost associated with CAM. Billions of dollars are spent worldwide on therapies that at most have marginal, non-specific or placebo affects on patients’ perception of their disease and at worst maim and kill patients and prevent them from taking advantage of truly effective medicine. And as Ernst and Singh carefully discuss, taking advantage of these placebo affects by lying to patients is a slippery slope that scientific medicine cannot afford to start down if we don’t want to end up where medicine was when Washington was killed by his doctors.

They also summarize nicely many of the reasons CAM is so popular despite the evidence against many of its practices. Both the active promotion by commercial interests and charismatic true believers, and the reticence of mainstream scientists to engage in controversy or to make effective use of the media are touched upon, as well as many other factors.

Overall, I cannot recommend this book highly enough. Certainly, anyone skeptical of CAM or honestly open-minded and curious will find much useful information as though-provoking discussion. Even proponents of CAM, other than those farthest out on the ideological fringe, will be impressed by the genuine interest of the authors in looking fairly and honestly at CAM therapies, even if they do not accept the book’s conclusions. Thoughtful, informative, cogent, and well-written, this one belongs on the shelf on anyone with an interest in CAM.

Posted in Book Reviews | 10 Comments

Is the Mainstream Media Becoming Skeptical?

Posted on June 9, 2009 by skeptvet

The mainstream media has always had a problem covering complementary and alternative medicine (CAM). It’s much like the problem they have covering the arguments about teaching evolution or creationism in public schools. The training of journalists to “tell both sides” of every story makes them try to present representatives and their points of view on two sides of any issue as if they were essentially equivalent. This may be an attempt to achieve objectivity, but without context it creates the erroneous and misleading impression that there is merely a difference of opinion among “experts” rather than a solid body of evidence and theory on one side (evolution, scientific medicine) and a relatively small cadre of faithful believers with little evidence to support their position on the other (creationism, CAM).

 

The media also likes a good David and Goliath story, and tends to cast the CAM community as small scale healers struggling to bring safe, natural remedies to the suffering against the opposition of large-scale, rich, corporate and academic machines trying to maintain their lucrative monopoly on the maintenance of illness. This ignores the truth of many hard-working, compassionate, and underpaid health care providers and many large-scale, wealthy supplement and alternative care industries, but it makes a more compelling narrative.

 

Lately, though, there have been a few small, encouraging signs that mainstream reporters can cover the issue of CAM in a way that accurately illustrates reality. Newsweek recently ran an article exposing the dangerous faith many of Oprah Winfrey’s viewers have in her opinions and those of the CAM “experts” (like actress Suzanne Somers) that she regularly promotes through her various media outlets (Live Your Best Life Ever).

 

Making the case that Oprah has a tremendous influence on people’s opinions and behavior, and that this should entail a responsibility on her to give truthful, accurate information, is a clear and cogent way to make an important point about unproven CAM approaches without in any way being biased on unfair.

 

Newsweek also ran an article in October, 2008 reviewing very generally reviewing the evidence for and against some popular CAM therapies (The Truth About Alternative Medicine). While the treatment of the evidence was somewhat superficial, the fact that the article emphasized looking at CAM in the same evidence-based way we look at mainstream medical practices is a step in the right direction.

 

Finally, Marilynn Marchione, a medical writer for the Associated Press, has written a couple of very sharp pieces recently pointing out that CAM is both very widespread and often not as safe as it is believed to be. (Alternative Medicine Goes Mainstream and 60 Pct of Cancer Patients Try Nontraditional Med)

I can’t remember the last time a mainstream media writer pointed out the naturalistic fallacy!

 

CAM advocates have a number of marketing advantages, and have made some smart strategically choices in how they characterize themselves and the medical mainstream, and science-based medicine is having to face the reality that being right about the facts is seldom as important in making a convincing argument as we’d like it to be. What media experts call “framing” is an important strategy, and these articles illustrate ways the debate can be framed that illustrate the true dangers of unquestioning acceptance of CAM and the importance of verifiable facts in making health care choices, while still remaining fair and open-minded. Let’s hope we see more of the like!

Posted in General | 1 Comment

The Appeal of Simplicity

Posted on June 5, 2009 by skeptvet

One of the great marketing advantage complementary and alternative medicine (CAM) has over mainstream science-based medicine is the appeal of simple explanatory narratives. Sometimes we get to take advantage of this in scientific medicine. Bacteria cause infections, antibiotics kill bacteria and the infections go away. This is a simple, satisfying story that can be told in a 25 or 30-minute office visit, and it gives the pet owner a sense that they understand the problem and the solution. But sadly, real life, and real medicine, isn’t always that clear cut.

 

Explaining the pathogenesis of cancer, or Cushing’s disease, or some idiopathic condition we don’t yet fully understand can be very frustrating for the vet and the pet owner. Without a clear and comprehensible description of the problem, and without a straightforward treatment or prognosis, the client begins to doubt the competence of their vet.

 

One of the best indications that many CAM approaches are not correct is that they seem never to face this problem. A chiropractor can always find a subluxation to blame for back pain. And if there is no pain, why that’s because the subluxation was corrected before it got bad enough to cause symptoms!

 

Homeopathy has a consistent and appealing narrative in the Law of Similars. This says that miniscule amounts of a substance which causes a symptom (or merely the energetic resonance left behind by the substance after it has been diluted away) can actually remove the symptom from the patient. The fact that this makes no physiologic sense, that most homeopathic remedies haven’t undergone “provings” to see if they can cause the symptoms they are used to treat, and that clinical trials have shown the stuff doesn’t work anyway is irrelevant. There is always a ready answer and a ready solution with a simple link between the two.

 

Unbalanced Ch’i or yin/yang, mysterious “toxins,” vertebral subluxations, and many other such entities all share some essential characteristics that make them appealing and persistent as explanations for disease.

 

They are unfamiliar to most people since they can only be identified by specially trained practitioners. This gives them a mysterious and sinister aura that makes it easy to inspire worry about their malign effects in people’s minds. Infectious agents don’t fit the role of villain nearly as well since people have come to expect, through the hard won success of vaccines and antibiotics, that if these were really the causes of their problem doctors should be able to find and eliminate them with no trouble. And complex sources of disease such as the multiple genetic and environmental and random chance effects spread out over decades that lead to most cancers are not sufficiently clear and circumscribed causes to fill the role of villain, nor can the practitioner of scientific medicine claim to be able to easily identify and vanquish them.

 

The sources of disease claimed by many CAM methods also share the characteristic of being ephemeral and not amenable to consistent, objective. Chiropractors almost never agree with one another about where the dreaded subluxation is, and homeopaths seeing the same patient seem to come up with widely different assessments and prescriptions. This seems like it should be a disadvantage to those of us accustomed to the scientific notion that one must clearly establish the objective reality of something before blaming disease on it. But actually the intangible quality of these etiologies makes them perfect villains. The CAM practitioner can always find them when they need an explanation for something, no one can gainsay this explanation since there is no objective standard for verifying the diagnosis, and if the patient gets better the practitioner can claim the cause is no longer there, again without any fear of being proven wrong. Sadly, in science-based medicine we are much more often forced to honestly admit when we cannot find the cause of a patient’s symptoms, we cannot ethically prescribe a treatment without some legitimate indication, and we can’t automatically claim the credit for improvement.

 

People desperately want simple, clear explanations for what is wrong with their pets. They want to know what the chances are of the problem getting better. And they want to know what needs to be done. All of these things allow the pet owner to either feel more in control of the scary thing that is happening to their pet, or at least to adjust their expectations and emotions to the inevitable. What people do not want is to be told that the cause of their pet’s illness is unknown, that the doctor cannot say with certainty what will happen, and that any treatment is an educated guess at best. To be fair, I have seen some CAM practitioners admit to not knowing what is wrong or to not being sure if their treatments will work. But far more often, where the science-based medical approach calls for painful honesty about the uncertainty involved, the CAM approach allows for confident, simple explanations of the problem and confident treatment recommendations.

 

Not being tied to an objective, verifiable physical reality, many CAM approaches can give people what they want and need emotionally when their pets are sick, even if they can’t actually offer anything of benefit to the patient. This is an advantage in terms of appealing to the public that scientific medicine cannot co-opt or undermine. Of course, scientific medicine often has the advantage of being right about the real causes and the appropriate treatments, and this often trumps the lack of appealing simplicity in scientific explanations. Very few CAM therapies have established themselves as popular treatments for acute, life-threatening diseases because they simply cannot compete with scientific medicine in terms of results. But when it comes to the vague and the chronic complaints that science does not yet have clear answers to, and for which indeed there may not even be clear answers to be found, we shall have to accept the disadvantage of being honesty about the complexity and uncertainty of these conditions. It is the price paid for holding out for real answers rather than simple, appealing, but ultimately empty stories.

Posted in General | 5 Comments

Veterinary Joint Supplements-Glucosamine & Chondroitin

Posted on June 5, 2009 by skeptvet

What is it?

 

Osteoarthritis (OA), also called degenerative joint disease (DJD), is a common and painful disease in older humans and animals. OA mostly affects cartilage, the hard but slippery tissue that covers the ends of bones where they meet to form a joint. Healthy cartilage allows bones to glide over one another with little friction. It also absorbs energy from the shock of physical movement.

In osteoarthritis, the surface layer of cartilage breaks down and wears away, exposing the underlying bone. Bone rubbing against bone causes pain, and leads to inflammation, a complex response which contributes to further cartilage loss and discomfort. Over time, small deposits of bone – called osteophytes or bone spurs – may grow on the edges of the joint. Bits of bone or cartilage can break off and float inside the joint space. This causes more still more pain and damage.

Because animals cannot directly inform their caretakers of mild discomfort, the first signs of OA in veterinary patients are usually lameness and a reluctance to engage in normal activities. By the time such signs are noticed, the condition has usually progressed to moderate or severe disease. A diagnosis of OA usually requires a physical examination by a veterinarian, who can identify subtle signs of pain, osteophytes, and reduced range of joint motion. X-rays can also help identify DJD, though these are not always reliable indicators of discomfort or function.

The primary treatments for humans and animals with OA are weight loss, regular moderate exercise, and pain medications, typically the non-steroidal anti-inflammatory drugs (NSAIDs). There has also been interest among some health care providers in so-called nutraceuticals- substances derived from food sources that might treat the symptoms or alter the progression of OA.

Glucosamine is a substance found in joint cartilage and joint fluid. It is normally produced by the body from basic ingredients in food, and some is incorporated into joints. Though glucosamine is only one of the many building blocks of cartilage, it has been theorized that supplementing glucosamine orally might stimulate production or repair of cartilage. Some researchers have also suggested glucosamine might reduce inflammation in arthritic joints and thus reduce discomfort and slow the progression of the disease. Most supplement forms of glucosamine are derived from shellfish.

 Chondroitin sulfate is another normal constituent of cartilage, and it has also been theorized to reduce inflammation and cartilage degradation in OA and perhaps to slow progression and improve comfort. Chondroitin in supplements is usually derived from cow cartilage.

Since glucosamine and chondroitin are categorized as nutritional supplements, they are not regulated by the Food and Drug Administration. Manufacturers do not have to prove that they are safe or effective in treating OA, and they do not have to abide by the strict quality control requirements for the production of approved drugs. Independent testing of over-the-counter glucosamine and chondroitin products have shown that they vary greatly in composition, and many do not actually contain the ingredients indicated on the label. Therefore, even if the substances have a role in treatment of OA, there is some concern that the actual preparations sold for humans and animals may not be of any value simply because they may not contain much of the ingredients.

 

Does It Work?

 

There has been a great deal of research on the effects of glucosamine and chondroitin on cells from joint tissues isolated in the laboratory. Though the results are inconsistent, some studies do show a number of actions on cells that might suggest a use for these agents in patients with OA, so the theory behind their use is plausible. However, there are other reasons for questioning whether these agents could actually work in a real patient.

 

For example, some controversy about whether oral preparations of chondroitin sulfate, which is a very large and electrically charged molecule, can be absorbed into the body and whether it actually get into joints affected with OA. Results of studies on the availability of oral glucosamine and chondroitin are extremely inconsistent, but generally show a low level of absorption in humans, rats, dogs, and horses. While some of the absorbed molecules do appear to reach affected joints, it is not clear if the amount is sufficient to have any effects. The amount that reaches the joints when the products are given orally is generally less than the amount used in the laboratory to demonstrate possibly useful actions on isolated cells and much less than the amount of glucosamine already circulating in the animal’s body.

 

Extensive clinical trials have been conducted in humans to determine if glucosamine and chondroitin can reduce symptoms or slow progression of OA. The best quality scientific studies require blinding, where the patients and researchers do not know whether each subject is getting the real treatment or a fake (placebo) treatment.  And many other factors complicate interpretation of human clinical trials, so confidence in the results can only come from consistent, repeatable outcomes of numerous well-designed trials conducted by different investigators.

 

The results of these clinical trials are also highly inconsistent. In general, older studies with small numbers of patients and funded by supplement manufacturers showed some benefit from oral glucosamine and chondroitin. However, as larger, independently-funded trials with more subjects and better design have been published, the evidence has become predominantly negative.

 

The largest and best trial so far is the Glucosamine/Chondroitin Arthritis Intervention Trial (GAIT), a study comparing glucosamine and chondroitin, separately and together, against placebo and an NSAID (celecoxib, or Celebrex). Overall, the NSAID improved comfort and function significantly more than the placebo, while the various glucosamine and chondroitin products did not. Another study of many of the same subjects over 2 years did not find any significant difference in loss of joint space on x-rays (a measure of progression of OA) compared to the placebo. On balance, then, the evidence in humans suggests little to no benefit of these agents on symptoms or progression of OA.

 

There is very little research on the use of glucosamine and chondroitin in OA for veterinary patients. A recent review found only one good quality study comparing a combination glucosmine/chondroitin product to NSAIDs and placebo in dogs. In this study, the NSAIDs showed significant benefit on both objective and subjective measures of pain compared with placebo, but there was no difference between the placebo and the nutraceutical product.

 

Therefore, though there are some interesting effects of chondroitin and glucosamine on joint tissue in the lab, there are also questions about whether they could be effective in real patients. The balance of the clinical research evidence in both humans and animals does not suggest there is any real benefit of oral supplementation of these agents in patients with osteoarthritis.

 

 

Is It Safe?

 

Oral glucosamine and chondroitin supplements appear to be safe. There is some possibility that they may interfere with platelets, an element in the process of blood clotting. Alone, this does not seem to be of any clinical significance, but it is recommended that they not be used in patients already on anti-coagulant medications such as aspirin, clopidogrel (Plavix), or heparin.

 

There are also some concerns about glucosamine interfering with treatment for diabetes since it is structurally similar to sugar. In humans, this does not appear to be a real risk for diabetic patients. There is no research on this issue in veterinary patients.

 

 

Summary

 

Ø     Glucosamine and chondroitin appear to have effects on joint tissues isolated in the laboratory that might indicate they could be useful adjuncts to osteoarthritis treatment if these effects also occurred in patients given oral preparations of these substances. However, there are reasons to question whether they could have such effects because they are poorly absorbed, and little of what is taken orally actually reaches affected joints.

 

Ø     In humans, the largest and best clinical trials studying oral glucosamine and chondroitin supplements shows little to no effect on pain or on the degeneration of cartilage in patients with osteoarthritis.

 

Ø     There is virtually no good quality research on the use of glucosamine and chondroitin in veterinary patients. The best study so far, done in dogs, found a combination of these agents to be of no benefit for patients with osteoarthritis. Further research in animals with osteoarthritis is warranted, but at this time the evidence does not support the use of glucosamine and chondroitin in these patients.  

 

Ø     Glucosamine and chondroitin taken orally appear to be safe in veterinary patients. However, they should not be taken by patients on anti-coagulant medications, and they should be used with caution in diabetics.

 

Ø     The best treatments for osteoarthritis in veterinary patients, as in humans, are maintenance of a healthy weight, regular moderate exercise, and non-steroidal anti-inflammatory medications for pain

 

 

References and More Information

Aragon, C.L., Hofmeister, E.H., Budsberg, S.C., Systematic review of clinical trials of treatments for osteoarthritis in dogs. J Am Vet Med Assoc 2007; Feb 15;230(4):514-21.

 

Barker Bausell, R., Snake Oil Science: The Truth About Complementary and Alternative Medicine, Oxford University Press, 2007

 

Clegg, D.O., et al. Glucosamine, Chondroitin Sulfate, and the Two in Combination for Painful Knee Osteoarthritis. N Engl J Med. 2006 Feb; 23;354(8):795-808.

 

Goggs, R., et al. Nutraceutical Therapies for Degenerative Joint Diseases:

A Critical Review. Crit Rev Food Sci Nutr 2005;45:145–164

 

Moreau, M., et al. Clinical evaluation of a nutraceutical, carprofen, and meloxicam for the treatment of dogs with osteoarthritis. Vet Rec 2003; 152:323-329

 

National Institute of Health, National Institute of Arthritis and Musculoskeletal and Skin Diseases. Handout on Health: Osteoarthritis 2006. http://www.niams.nih.gov/Health_Info/Osteoarthritis/osteoarthritis_hoh.pdf

 

Neil, K.M., Caron, J.P., Orth, M.W. The role of glucosamine and chondroitin sulfate in treatment for and prevention of osteoarthritis in animals. JAVMA  Apr 2005;226(7);1079-1088

 

Sawitzke, A.D. The effect of glucosamine and/or chondroitin sulfate on the progression of knee osteoarthritis: A report from the glucosamine/chondroitin arthritis intervention trial. Arthritis Rheum 2008 Oct;58(10):3183-91

 

The Cochrane Collaboration, The Cochrane Reviews, a searchable database of systematic reviews of the human medical literature at http://www.cochrane.org/reviews/

 

 

© Brennen McKenzie, 2008

 

 

Posted in Herbs and Supplements | 27 Comments

Veterinary Probiotics

Posted on June 5, 2009 by skeptvet

What is it?

 

A widely used definition of probiotics is “Live microbes that, when administered in adequate amounts, confer a health benefit on the host.” The basic idea is that all animals have a great number and variety of microorganisms living in and on their bodies, and that many of these microbes are commensuals, organisms that benefit from living on the host and that in return convey some benefit to the animal. Such benefits include inhibiting disease-causing organisms from colonizing the host, producing nutrients for the host, and possibly participating in the normal development and regulation of the immune system. Animals raised in laboratories without any colonizing microbes, and animals with abnormal numbers and types of microbes, often experience disease, so it is believed that an appropriate microbial ecology is important for normal health and function.

 

Though many organisms have been used, most probiotic products contain bacteria, often from the Bifidobacteria or Lactobacillus groups, or Saccharomyces (brewer’s yeast). While some of the bacteria suggested as probiotics are natural parts of the gut ecology, many strains are not, and brewer’s yeast of course does not normally live in or on animals.

 

To be potentially useful, a probiotic organism must not normally be capable of causing disease (though many are opportunistic pathogens, able to cause disease under certain circumstances). It must be able to survive the acidic environment of the stomach and at least temporarily survive in the intestines, where most normal bacterial flora is found. Typically, probiotic organisms do not colonize individual animals well and must be taken continuously to be present in any number. Finally, a probiotic preparation must contain enough live organisms in an appropriate delivery vehicle to enable colonization of the intestines.

 

While the scientific principles behind probiotics are sound, there are a number of problems with the practical use of such preparations. Every individual animal has a complex ecology of microbes colonizing it, and the specific type and number depend on species, environment, community, and individual genetics. Even for humans, as many as 80% of the organisms we harbor have yet to be identified or studied, and much less is know about the microbial ecology of companion animals. So trying to manipulate this ecology and the health of the individual by adding a few bacteria, often of a strain not naturally found in the individual, may not make sense. Also, numerous tests have shown that commercial probiotic products often do not contain the organism they claim, they are sometimes contaminated with undesirable organisms, and they may have too few microbes or non-living microbes in them. Without any formal government regulation or monitoring it is difficult to know whether individual products are safe or effective.



 

 

Does It Work?

Much laboratory research has been done on many different potential probiotics, and there is good evidence to support the principle that such organisms can influence health and disease. Clinical studies in humans, however, have often produced mixed or disappointing results.

 

Based on clinical trials in humans, the balance of the evidence supports the effectiveness of some probiotic preparations for prevention and treatment of diarrhea caused by antibiotics, infection, or radiation treatment and for treatment of lactose intolerance. There is also good evidence for their use in irritable bowel syndrome and some other inflammatory gastrointestinal tract diseases. The evidence is inconclusive for most uses of probiotics, including in preventing or treating traveller’s diarrhea, urinary tract infections, fatty liver syndrome, and Helicobacter infections responsible for stomach ulcers. Research evidence does not support the use of probiotics in Crohn’s disease, ulcerative colitis, asthma, allergic eczema, or rheumatoid arthritis.

 

Further research may find other potential benefits from probiotics, but because the composition and function of the normal microbial ecology is so poorly understood, it is not yet clear which conditions may benefit from the use of which organisms. At this time clinical studies are largely based on haphazard selection of products and conditions rather than on strong, plausible scientific hypotheses.

 

While there has been extensive research on the effect of probitics in livestock, there are very few published studies on their use in companion animals. Studies in horses have shown poor colonization of human-derived organisms. Several trials have failed to show any benefit of probiotics on the shedding of disease-causing organisms such as Salmonella. One small study suggested some benefit from brewer’s yeast in treatment of diarrhea, although the duration o hospitalization and the overall outcome was not affected by the treatment.

 

In dogs, human-derived organisms are also ineffective at colonizing the intestines. Dog-derived microbes do seem to reach and survive in the intestines, but no clinical for these has yet been demonstrated. And in cats, there are no published research studies on the use of probiotics for prevention or treatment of disease.

 

The marketing literature accompanying veterinary commercial products often claims safety and efficacy based on company studies or other unpublished research. While these findings are interesting, it has been clearly shown that industry-sponsored research is more likely than independant research to find results in favor of the product being tested. In addition, such marketing materials deliberately avoid any research that does not favor the product, so while useful such materials cannot be relied upon exclusively to decide if a product is safe or effective.

 

Is It Safe?

There are very few reports of disease or harm caused by probiotics. Individuals with ineffective immune systems (such as the elderly, pregnant women, people with HIV or receiving chemotherapy) are at increased risk of disease from all microbes, and there have been cases of severe illness caused by bacterial or yeast infections from probiotic products given to the patient or to others in their hospital unit. Very sick or immunocompromised individuals should not use these products. Interestingly, however, newborns and infants have often been subjects in studies of probiotics, and the majority show no adverse effects.

 

Some probiotic organisms are closely related to disease-causing microbes. Enterococcus faecium is a widely available veterinary probiotic related to other members of the Enteroccocus group, which commonly cause serious infections. Such organisms have the potential to cause illness or to share genes for antibiotic resistance with other, disease-causing members of the same group.

 

Some risks from probiotics are related to their intended functions, to interact with the microbial flora and affect the immune system. In horses, one study of a probiotic given to prevent diarrhea found the product actually caused diarrheal illness is neonatal foals. A study in dogs showed the probitoic Enterococcus faecium potentially improved the attachment to the intestines of the disease-causing organism Campylobacter. And other studies have shown some inflammatory conditions, such as allergic rhinitis, can increase in people given probiotics for another condition. So while the balance of the evidence is that these products are quite safe, because they do have real effects on the body they can potentially have unintended or undesirable effects.

 

 

Summary

 

Ø     A normal microbial flora is beneficial, and perturbations in the normal flora are associated with disease, so the principle that manipulating the microbial ecology can affect health is reasonable.

 

Ø     The normal microbial flora is complex and poorly understood, so how to appropriately manipulate it to achieve health benefits is not yet clear.

 

Ø     Clinical studies in humans are mixed, showing benefits from some probiotic products for some conditions, no benefit in other cases, and inconclusive results for many products and conditions.

 

Ø     There is little reliable research in companion animals regarding the safety or efficacy of probiotic products.

 

Ø     The risks of probiotics are probably very low. Individuals with compromised immune systems are at greatest risk and should not be exposed to probiotics. There is some limited potential for these products to cause disease even in healthy individuals.

 

 

References and More Information

The Cochrane Collaboration, The Cochrane Reviews, a searchable database of systematic reviews of the human medical literature at http://www.cochrane.org/reviews/

 

Crislip, M. Probiotics. Science-Based Medicine Blog. http://www.sciencebasedmedicine.org/?p=344#more-344

 

FAO/WHO. Guidelines for the evaluation of probiotics in food. http://www.who.int/foodsafety/fs_management/en/probiotic_guidelines.pdf

 

Rice, L.B., et al. Transferable, Plasmid-Mediated VanB-Type Glycopeptide Resistance in Enterococcus faecium. Antimicorbial Agents and Chemotherapy  1998 April; 42(4): 963–964

 

Rinkinen, M., et al. Interaction between probiotic lactic acid bacteria and canine enteric pathogens: a risk factor for intestinal Enterococcus faecium colonization? Vet Microbiol 92: 111-119

 

Versalovic, J., Wilson, M., Eds. Therapeutic Microbiology: Probiotics and Related Strategies, ASM Press, Washington, DC, 2008

 

Weese, J.S. Microbiologic evaluation of commercial probiotics. JAVMA 2002; 220(6): 794-797

 

Weese, J.S., Rousseau, J. Evaluation of Lacotbacilluc pentosus WE7 for prevention of diarrhea in neonatal foals. JAVMA 2005; 226(12): 2031-2034

 

Wynn, S.G. Probiotics in veterinary practice. JAVMA 2009; 234(5): 606-613

 

© Brennen McKenzie, 2008

 

 

 

 

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