Just to let all readers know, on January 28th, I will be hosting the 129th Skeptics’ Circle, a biweekly blog carnival collecting and presenting articles applying the skeptical point of view to a wide variety of issues. I’ve had a few of my own articles included in past Circles, and I’m very excited to have a chance to host!
Check out the recent 127th Circle, and remeber to check back for some ggreat skeptic writing January 28th! Or even better, contribute a blog post of your own!
The question of whether the electromagnetic radiation from cell phones is a risk factor for human disease, especially brain cancer, has been debated and studied at length. There are committed partisans on both sides, but the research is inconsistent and incomplete. A couple of nice summaries and discussion of the issue and the research can be found at the National Cancer Institute and The Skeptics Dictionary. Overall, it seems unlikely to me that cell phone usage represents a significant risk, but the issue has not been decided beyond all reasonable doubt.
However, a recent study has added a bit of fun to the discussion by claiming cell phone radiation may prevent or reverse Alzheimer’s disease! According to news articles about the study:
“The results showed that:
Exposure started when they were young adults, ie before showing signs of memory impairment, appeared to protect the Alzheimer’s mice from becoming cognitively impaired.
Exposed older Alzheimer’s mice performed as well on tests measuring memory and thinking skills as normal older mice without dementia.
When older, previously unexposed Alzheimer’s mice already showing memory problems were exposed to the electromagnetic field, their memory impairment vanished.
Normal mice exposed to the electromagnetic waves for several months showed above normal memory performance.”
The authors seem quite optimistic about the applicability of the results to human disease:
“Since we selected electromagnetic parameters that were identical to human cell phone use and tested mice in a task closely analogous to a human memory test, we believe our findings could have considerable relevance to humans.”
“Arendash and colleagues concluded that electromagnetic field exposure could be an effective, drug-free, non-invasive way to prevent and treat Alzheimer’s disease in humans.”
“The cognitive benefits of long-term electromagnetic exposure are real, because we saw them in both protection- and treatment-based experiments involving Alzheimer’s mice, as well as in normal mice.”
It should come as no surprise that I don’t share this enthusiasm. The results are certainly interesting, but this is precisely the sort of small, animal model study that the media loves to extrapolate wildly from, contributing to the public perception that science is constantly finding phony “miracle cures” and that scientific research results cannot be trusted. The problem, as I’ve argued before, is not with science but with individuals, scientists and others, who treat such curious and preliminary results with excessive enthusiasm.
Talking about a “effective, drug-free, non-invasive way to prevent and treat Alzheimer’s disease” based on exposing mice to EM in the lab and then looking at their behavior and their brains is indefensible. Replication in other laboratories, further elucidation of possible mechanisms, study of safety concerns, and the whole labyrinth of procedures in human subjects to assess safety and efficacy are needed, years of work, before such speculations ought to be publically entertained. I’ve often pointed out that being part of mainstream science and medicine does not, alas, immunize one against some of the lapses in critical thinking often associated with CAM, and this provides another example.
Still, it will be interesting, though, to see what reaction this study generates in the alternative medicine community. I suspect those enamored of “natural” medicine will reject as unholy any such technological methods regardless of whether they ultimately prove useful. I also suspect that if the exact same study came out only “electromagnetic radiation” was replaced throughout with the name of an herb or traditional energy therapy, such a study would be nearly universally proclaimed as justification for immediate use of the agent or procedure in human clinical practice. This is, after all, exactly the sort of evidence proponents of “Evidence-Based Alternative Medicine” routinely rely on.
It is widely known by veterinarians, pet owners, and dog breeders that large breed puppies are at greater risk than other breeds for developmental disorders of the bones and joints, including hip dysplasia, elbow dysplasia, osteochondrosis dissecans (OCD), and hypertrophic osteodystrophy (HOD).[1,2] The breed predisposition for such disorders indicates a strong genetic component, however environmental factors can also influence the frequency of these disorders.[2,3] Nutrition during the growing period (birth until 10-12 months) is one of the most important factors influencing the development of these skeletal disorders. [2] Unfortunately, there are many myths about large breed puppy nutrition, so this article is an attempt to separate these from the real facts about developmental nutrition in large breed puppies.
Calories
By far the most important influence on the skeletal development of large breed puppies is total calories. Excess calories leads to more rapid growth and excess body weight, and these are associated with increased incidence of hip dysplasia, OCD, and elbow dysplasia.[4-8] Lower calorie diets do not reduce the ultimate stature a dog will achieve, but they reduce the rate of growth so that this size is achieved smoothly over the growth period rather than in a rapid burst.[9] This slower, more steady growth leads to fewer developmental orthopedic problems. he appropriate number of calories needed for optimal growth is different for every individual and depends on many factors. The best guideline for how much to feed is body condition. Several scoring systems are available (e.g. from Purina below), and puppies should be fed to an ideal condition (4/9 or 3/5).
Calcium
As with most nutrients, there is an optimal range of calcium levels for growing dogs. Both too much and not enough calcium can lead to developmental bone problems. For large breed dogs, this optimal range is narrower than for other breeds, and excessive levels of calcium cause OCD and other bone disorders earlier and with more severe consequences. While not all studies agree, the majority show a strong link between high calcium levels in the diet and bone problems, even when the levels of calories and other nutrients are the same. Though the level of calcium which increases the risk of skeletal problems varies with age, a calcium level of 210-540mg calcium per kilogram of body weight per day appears safe for large breed puppies of all ages. It is also important not to add vitamin and mineral supplements containing calcium to properly balanced puppy diets as this is very likely to increase calcium intake beyond safe levels. [2,5,10-12]
Protein
Many breeders and pet owners, as well as some veterinarians believe too much protein can contribute to developmental skeletal disorders in large breed puppies, but this is incorrect. An early study [5] observed orthopedic problems in dogs fed diets high in calories, protein, and calcium, but subsequent studies clarified that protein is not a risk factor for any of these problems.[13]
Diet Recommendations
The best way to meet the optimal dietary requirements for large breed puppies is with a commercial diet specifically designed for this purpose. Though many people recommend feeding an adult food, with the idea that it is lower in calories than regular puppy food, adult diets vary widely in calorie content, so this is not automatically true. Additionally, adult diets are not usually appropriately restricted in calcium content. It is also important not to add vitamin and mineral supplements containing calcium to properly balanced puppy diets as this is very likely to increase calcium intake beyond safe levels.
If you choose to feed a homemade diet or to supplement a commercial diet with table food or other additional ingredients, it is important to consult a nutritionist to ensure that the resulting diet has appropriate levels of calories and calcium to reduce the risk f developmental orthopedic disease.
References
1. Lauten SD. Nutritional risks to large-breed dogs: from weaning to the geriatric years. Vet Clin North Am Small Anim Pract. 2006 Nov;36(6):1345-59.
2. Hazewinkel H, Mott J. Main nutritional imbalances in osteoarticular diseases. In: Pibot P, Biourge V, Elliott D, editors. Encyclopedia of canine clinical nutrition. Aniwa SAS; 2006. p. 348-83.
3. LaFond E, Breur GJ, Austin CC. Breed susceptibility for developmental orthopedic diseases in dogs. J Am Anim Hosp Assoc. 2002 Sep-Oct;38(5):467-77.
4. Kealy RD, Lawler DF, Ballam JM, et al. Five-year longitudinal study on limited food consumption and development of osteoarthritis in coxofemoral joints of dogs. JAVMA. 1997;210:222-25.
5. Hedhamer A, Wu F, Krook L, et al. Overnutrition and skeletal disease: an experimental study in growing Great Dane dogs. Cornell Vet. 1974;64(1; Suppl 5):59.
6. Kastrom H. Nutrition, weight gain, and development of hip dysplasia. Acta Radiol. 1975;344(suppl):135.
7. Lavelle RB. The effect of overfeeding of a balanced complete commercial diet to a young group of Great Danes. In: Burger IH, Rivers JPW, editors. Nutrition of the dog and cat. Cambridge (MA), USA. Cambridge University Press; 1989. p. 303-15.
8. Grondalen J, Hedhammer A. Nutrition of the rapidly growing dog with special reference to skeletal disease. In: Anderson RS, editor. Nutrition and behavior in dogs and cats. Oxford, UK. 1982. 81-8.
9. Dammrich K. Relationship between nutrition and bone growth in large and giant dogs. J Nutr. 1991 Nov;121(11 Suppl):S114-21.
10. Hazelwinkel HAW, Goedegeburre SA, Poulos PW, et a;. Influence of chronic calcium excess on the skeletal development of growing Great Danes. J Amer Anim Hosp Assoc. 1985;21:337-91.
11. Schoenmakers I, Hazelwinkel HAW, Voorhout G, et al. Effects of diets with different calcium and phosphorus contents on the skeletal development and blood chemistry of growing Great Danes. Vet Rec. 2000;147:652-60.
12. Weber M, Martin L, Dumon H, et al. Growth and skeletal development in two large breeds fed 2 calciu levels. J Vet Int Med. 2000;388.
13. Nap RC, Hazelwinkel HAW, Voorhout G, et al. Growth and skeletal development in Great Dane pups fed different levels of protein intake. J Nutr. 1991;121:S107-113.
Too Thin
1 Ribs, lumbar vertebrae, pelvic bones and all bony prominences evident from a distance. No discernible body fat. Obvious loss of muscle mass.
2 Ribs, lumbar vertebrae and pelvic bones easily visible. No palpable fat. Some evidence of other bony prominence. Minimal loss of muscle mass.
3 Ribs easily palpated and may be visible with no palpable fat. Tops of lumbar vertebrae visible. Pelvic bones becoming prominent. Obvious waist.
Ideal
4 Ribs easily palpable, with minimal fat covering. Waist easily noted, viewed from above. Abdominal tuck evident.
5 Ribs palpable without excess fat covering. Waist observed behind ribs when viewed from above. Abdomen tucked up when viewed.
Too Heavy
6 Ribs palpable with slight excess fat covering. Waist is discernible viewed from above but is not prominent. Abdominal tuck apparent.
7 Ribs palpable with difficulty; heavy fat cover. Noticeable fat deposits over lumbar area and base of tail. Waist absent or barely visible. Abdominal tuck may be present.
8 Ribs not palpable under very heavy fat cover, or palpable only with significant pressure. Heavy fat deposits over lumbar area and base of tail. Waist absent. No abdominal tuck. Obvious abdominal distension may be present.
9 Massive fat deposits over thorax, spine and base of tail. Waist and abdominal tuck absent. Fat deposits on neck and limbs. Obvious abdominal distention.
I’ve pointed out before that despite the David and Goliath myth CAM proponents often market, that CAM is big business. A study in July, 2009 from the National Center for Complementary and Alternative Medicine (NCCAM) reaffirms this. With all the usual caveats about the reliability of such surveys, the results found that adults in the United States spent $33.9 billion out of pocket on “alternative” medicine, exclusive of any insurance coverage or reimbursement for such treatment. Now, the NCCAM has some loose definitions of CAM, and it includes massage, yoga, and some other practices and products which may be considered CAM if they are provided or used with the intent to treat or prevent disease, but which may also be used for perfectly legitimate, non-medical reasons. Still, the numbers suggest there is a good deal of money to be made selling products and services that do not have a sound scientific basis, and this represents a real threat to the well-being of Americans.
The $33.9 billion represents about 11% of out-of-pocket health care expenditures, and the lion’s share of this (43.7% or $15.4 billion) went to non-vitamin/non-mineral herbs and supplements. That still left a respectable $3.9 billion for chiropractors and osteopaths and $2.9 billion for homeopathic remedies. Another, and scary way of looking at this, is that out-of-pocket expenditures on supplements and herbs was about 30% of that spent on prescription medications, and expenditures on CAM providers was about 25% of what was spent to see physicians. Granted, it is likely that the bulk of the overall $2.2 trillion spent on health care, which is insurance-reimbursed, is spent on scientific medical care, but it is still amazing that such large percentages of what people fork over out of their own pockets for health care goes to unproven “natural remedies” or thoroughly discredited nonsense like homeopathy. This confirms that people have a poor ability to judge the reliability of the health care information they receive and are easily taken advantage of, intentionally or not, by providers of unproven or bogus medical approaches.
So the next time a CAM proponent suggests that advocates of scientific medicine are Big Pharma shills trying to deny people safe and effective natural therapies because these are FREE, you might want to point them in the direction of this study.
Back in September, I reviewed the evidence (or lack thereof) supporting claims of benefits from nutraceuticals in cognitive dysfunction. One of the more popular ingredients in many of the products sold with such claims is Ginkgo biloba, and at the time of my earlier review I concluded:
“The clinical trial evidence in humans does not support a beneficial effect for cognitive impairment or dementia, as summarized in a Cochrane review…”
This month, a new study of ginkgo biloba for prevention of cognitive decline in humans has been published in the Journal of the American Medical Association. It is a large, multicenter, randomized, double-blinded, placebo-controlled prospective clinical trial, and thus represents a very high level of evidence. It concludes quite clearly.\
“Compared with placebo, the use of G biloba, 120 mg twice daily, did not result in less cognitive decline in older adults with normal cognition or with mild cognitive impairment.”
Another nail in the coffin for this particular wonder-herb.
There are many dogmatic opinions available from veterinarians, pet owners, breeders and others concerning a common question owners of new puppies have, How much exercise is ok for puppies? This is an especially pertinent question for owners of large breed puppies, since these breeds have a higher incidence than others of developmental orthopedic disorders such as hip dysplasia, elbow dysplasia, and cartilage abnormalities known as osteochondrosis dissecans (OCD). As is all too often the case, however, these opinions generally lack solid scientific evidence to support them. Very little is known about the precise risks and benefits of different types and intensities of exercise in growing animals.
One case control observational study [1] surveyed dog owners and found playing with other dogs to be a risk factor for OCD. Another, similar study [2] found chasing balls and sticks was a risk factor for development of hip dysplasia and elbow abnormalities. However, these studies cannot answer the overall question, which is how much and what kinds of exercise pose how great a risk and provide how great a benefit. One study [3] found exercise to be part of the treatment of carpal laxity, another joint abnormality seen in large breed puppies, and there is no question that exercise has many benefits, including reducing the risk of obesity and simply being part of a normal, enjoyable life for a puppy.
There are many more studies on the effects of exercise in children than in puppies, and though it is always risky to extrapolate from one species to another, some useful information can be gained by using one organism as a model for another, as long as conclusions drawn in this way are cautious and tentative pending better data. In general, while some intense and repetitive exercise can pose a risk of damage to growth plates in children, exercise is overall seen as beneficial in improving bone density and reducing the risk of obesity and related health problems.
The research evidence, then, really does not provide anything like a definitive answer to questions about the effects of exercise in growing puppies. Common sense suggests that forcing a dog to exercise heavily when it does not wish to is not a good idea. Likewise, puppies sometimes have more enthusiasm than sense and can exercise to the point of heat exhaustion, blistered footpads, and other damage that may be less obvious. Therefore, a general principle of avoiding forced or voluntary extreme exercise is reasonable, but specific and absolute statements about what kind of exercise is allowed, what surfaces puppies should or should not exercise on, and so forth is merely opinion not supported by objective data. Such opinions may very well be informed by personal experience, and they may be reliable, but any opinion not founded on objective data must always be taken with a grain of salt and accepted provisionally until such data is available.
1. Slater MR, Scarlett JM, Donoghue S, Kaderly RE, Bonnett BN, Cockshutt J, et al. Diet and exercise as potential risk factors for osteochondritis dissecans in dogs. Am J Vet Res. 1992 Nov;53(11):2119-24.
2. Sallander MH, Hedhammar A, Trogen ME. Diet, exercise, and weight as risk factors in hip dysplasia and elbow arthrosis in Labrador Retrievers. J Nutr. 2006 Jul;136(7 Suppl):2050S-2052S.
3. Cetinkaya MA, Yardimci C, Sa?lam M. Carpal laxity syndrome in forty-three puppies.Vet Comp Orthop Traumatol. 2007;20(2):126-30.
Much virtual ink has been spilled over the United Stated Preventative Services Task Force (USPSTF) breast cancer screening recommendations. Though I’ve written in general terms about the generally underappreciated complexity of screening tests and whether they are the unadulterated good most people think, the specifics of the USPTF recommendations and ensuing controversy have been covered at Science-Based Medicine and by Orac at Respectful Insolence with great detail and insight, so I have not felt motivated to contribute to the discussion surrounding them. However, the aspect of the brouhaha that strikes me as most disturbing and most central to the core issues I deal with here at SkeptVet blog, how to improve the practice of medicine through better use and reliance on science and scientific evidence, have recently been expressed succinctly on the KevinMD Blog. The post is short and to the point, so I will quote it in its entirety with all emphasis being mine:
“The fallout from the mammogram screening guidelines have served as a test case, of sorts, to see how the politicians and public will respond to recommendations based on evidence-based clinical practice.
And, judging from the inflammatory reaction, it’s safe to say that we’re quite a ways from medical decisions based on the best available data.
In a recent editorial, the New York Times touched upon the issue. One of the Senate’s health care bill amendments explicitly mentioned the USPSTF and “directed the government to ignore the task force’s most recent mammography recommendations.”
It overwhelmingly passed.
Health reformers are hoping that results from comparative effectiveness trials can help reduce the amount of practice variation, which is a leading driver of rising health spending.
But whenever the evidence calls for less medicine, the political and public outcry will be deafening. Today it’s mammograms. What if tomorrow an independent body calls for, say, a reduction of angioplasty or cardiac bypass surgery, which studies have suggested are being overused?
Both the politicians and the public will simply cry, “Rationing!” Thus, the myth that more care is better care will continue to be perpetuated, and the data ignored.”
I strive to avoid cynicism in my outlook on the future of science-based medicine, but I have to agree wholeheartedly with these sentiments. Orac has illustrated flaws and errors in the way the recommendations were marketed to the public, but while he may well be right, I think it is beside the point. Fear and a natural risk aversion makes us predisposed to make bad judgments about risk and benefit and to always seek what appears superficially like the safest course even when the data shows it is not the most likely to lead to a good outcome. It is difficult for doctors to do nothing even when that is the right thing to do, and it is even more difficult to convince patients and clients that it is sometimes better not to intervene with a test or treatment. Primum non nocere (First do no harm) is a cliché, but despite the fact we’ve all heard it, we seem constitutionally challenged when it comes to heading it. Hmmm, maybe if we printed it on T-shirts and gave them away to doctors? Seems to work for the pharmaceutical reps. Or perhaps we simply have to give up on the current generation and focus on teaching critical thinking starting in pre-school, inculcating the habit of ignoring one’s own intuition when the data says we should? Any ideas?
I stumbled across an article in the Israeli newspaper Haaraetz indicating that Council for Higher Education, the national accrediting body for higher education, has declined to permit complementary and alternative medicine programs to offer academic degrees. According to the article:
“[the Council] rejected several requests on the matter, saying there was no scientific basis for the practice…’Almost all studies show clearly that there is no scientific basis for alternative medicine,’ the council said yesterday.
While conceding that the various health maintenance organizations operate extensive alternative medicine treatment programs, they said ‘from that to academization is a very long way.'”
What a refreshing application of reason and science to a policy decision. The council recognized that CAM is widely practiced in Israel but rejected the argument of a subcommittee that it is better to legitimize it by accrediting the CAM education programs in order to somehow control the “quality” of the CAM offered. That argument makes little sense since it is pointless to ensure only the highest quality nonsense can be granted the imprimatur of a college degree. A PhD in astrology is just as meaningless as an unaccredited degree in the subject.
It would be nice to imagine such a level of common sense could one day apply to the accreditation process in smaller, less developed nations with less sophisticated educational systems, like the U.S. But I don’t imagine we’ll see that any time soon.
I am often struck by what I consider one of the great mysteries of CAM: how theories and approaches that are mutually inconsistent and incompatible are unified under the CAM umbrella without any apparent notice being taken of their mutually exclusive dogmas. The American Holistic Veterinary Medical Association (AAVMA), which I’ve written about before, is the paragon of this phenomenon. The organization supports and publishes “research” articles about almost any quack therapy without discrimination, so long as it cannot be said to be solidly based on scientific research evidence. The siege mentality seems to blind members of the CAM community to their internal differences.
Chiropractic is based on the theory that a mystical energy called innate intelligence travels through the spine and that subtle misalignments of the vertebrae (subluxations) block the normal flow of this energy, which leads to all disease. Granted, some chiropractors treat these ideas much like many Christians treat the Bible, as metaphors rather than literal truth, but the idea is still the foundation of the method and still widely invoked, especially since those chiropractors who have renounced it are left rather lamely claiming that their method works because people say it works even if no one can say why.
Traditional acupuncture, insofar as it has any consistent theoretical foundation, relies on the similarly vitalistic concept of qi which gets blocked or unbalanced to cause all disease. Manipulation of the qi as it flows through meridians by penetration with needles is the key element of acupuncture therapy. Again, some acupuncturists have attempted to jettison the vitalism underlying the tradition of their approach, though they haven’t come up with a demonstrable, consistent alternative explanation of how acupuncture might work, but many still employ the traditional concepts and language.
Homeopathy is based on another vitalist force gone awry, only this time the key to treatment of all disease is identifying a natural substance that induces the same symptoms as a particular disorder (Law of Similars) and then making it into a potent medicine by diluting and shaking it (Law of Infinitesimals and succussion). The contortions of homeopaths to try and rationalize this nonsense by bizarre interpretations of quantum mechanics are especially entertaining.
Many less popular CAM approaches rely on similar vitalist concepts, and yet many, many of them claim a unitary cause of disease and a single method for treatment, and no one seems to notice that all of these theories and all of these treatments cannot all be the one true cause/treatment of disease. Yet it is quite common for practitioners and patients alike to combine methods and recommend several or all of them. Clearly, the reality is that whatever unites these folks, it is not a particular theory nor even a commitment to their various one true answers. So what is it?
Well, epistemologically of course it is the belief that personal experience and intuition are reliable and sufficient to confirm the truth of an idea or the efficacy of a therapy. There is a strong tendency to a post-modernist relativism that suggests multiple incompatible truths can all be true for someone somewhere since there is no single physical reality out there waiting to be understood, as methodological naturalism and most scientific epistemology assumes.
Politically, CAM practitioners share a sense of being bold and unconventional thinkers surrounded by an oppressive and unimaginative orthodoxy marching in lockstep and suppressing all dissent. The reality is quite different, as CAM has become a well-financed and politically powerful lobby, but the image still persists in the minds of many practitioners and users.
CAM proponents often view the world as “toxic” and see the benefits of technology and science as hiding malign and poisonous underbellies. They tend to view history as a decline from a romanticized golden age in which humans lived in a state of nature and were healthier and happier to a time of decay in which science serves only to abuse and oppress the earth and the body.
There are undoubtedly other philosophical and aesthetic commonalities to the CAM movement, and I think it would be a fascinating topic for detailed study. Unfortunately, the general distrust of the very notion that there is a single objective reality that exists for everyone everywhere and that isn’t influenced at all by our beliefs or feelings makes possible a kind of doublethink in which mutually inconsistent medical theories can all be true. This makes it possible to suggest with a straight face that CAM might really be “complementary” even to scientific medical practice while still rejecting the very philosophical and epistemological premises that underlie science-based medicine. It would be nice if pointing out the logical inconsistency here had an impact on the beliefs of CAM followers, but they are well-protected against such reasoning.
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