Monday, April 20, 2009

Homemade and raw pet food diets-NOT safer.

Homemade and raw pet diets have gained in popularity over the last year or two, especially after the boost they gained with the melamine contamination problems in many commercial pet foods.
Raw diets for dogs and cats often use meat and organs from commercial sources and can contain harmful bacteria such as Salmonella, Campylobacter, E. Coli and Klebsiella among others. Some raw diets contain whole bones or large pieces of bone that can break teeth or cause intestinal obstruction.
A paper published last week in JAVMA last week illustrates another potential problem with this type of diet. There are several suppliers of diet mixes that are designed to be mixed with raw or cooked ingredients by the owner and then fed to the pet. Most claim to be complete diets appropiate for feeding to puppies and adult dogs, or kittens and cats.
In this case at least, the diet was profoundly insufficient in minerals and vitamins and nearly killed the puppy. The dog recovered after several months on commercial dog food. Diets should be tested and approved by the Association of American Feed Control Officials (AAFCO). Food with this approval should have the appropriate levels of nutrients for the life stage of the pet you are feeding.
The abstract of the paper is quoted below as it requires a subscription to view;
Diffuse osteopenia and myelopathy in a puppy
fed a diet composed of an organic premix
and raw ground beef
Mark B. Taylor, ma, dvm; David A. Geiger, dvm;
Korinn E. Saker, dvm, phd, dacvn; Martha M. Larson, dvm, ms, dacvr
Case Description—An 8-month-old Shetland Sheepdog was evaluated because of the
sudden onset of signs of neck pain, collapse, and inability to rise. A cursory diet history
indicated that the dog had been fed a raw meat–based diet.
Clinical Findings—Initial evaluation of the dog revealed small physical stature, thin body
condition, and signs of cranial cervical myelopathy. Radiographically, diffuse osteopenia of
all skeletal regions was identified; polyostotic deformities associated with fracture remodeling
were observed in weight-bearing bones, along with an apparent floating dental arcade.
Hypocalcemia and hypophosphatemia were detected via serum biochemical analyses. The
dog’s diet was imbalanced in macronutrients and macrominerals.
Treatment and Outcome—The dog received supportive care and treatment of medical
complications; neurologic abnormalities improved rapidly without intervention. Dietary
changes were implemented during hospitalization, and a long-term feeding regimen was
established. Following discharge from the hospital, exercise restriction was continued at
home. Serial follow-up evaluations, including quantitative bone density measurements, revealed
that dietary changes were effective. After 7 months, the dog was clinically normal.
Clinical Relevance—In the dog of this report, vitamin D–dependent rickets type I and suspected
nutritional secondary hyperparathyroidism developed following intake of a nutritionally incomplete
and unbalanced diet. The raw meat–based, home-prepared diet fed to the dog was not feedtrial
tested for any life stage by the Association of American Feed Control Officials, and its gross
nutrient imbalance induced severe metabolic, orthopedic, and neurologic abnormalities. Inadvertent
malnutrition can be avoided through proper diet assessment and by matching nutrient profiles with
patients’ nutritional needs. (J Am Vet Med Assoc 2009;234:1041–1048)

Sunday, April 19, 2009

Another reason not to use the Argument from Antiquity

The Argument from Antiquity is a logical fallacy that is used very commonly in support of various types of alternative medicine. The fact that a particular treatment has been used for hundreds or thousands of years says nothing about the efficacy or safety of that treatment. Treatments used before scientific understanding of biology and medicine were invented by trial and error at best and were often based on profound ignorance or misunderstanding of the processes involved. At the time they were invented, all medicine veterinary or human, was in the same category. Some of the treatments used for many years were dangerous and harmful (bleeding, treatment with toxic heavy metals, etc.). Some treatments are "safe" and cause no toxicity or side effects because they have no effect at all. Some of these treatments may have survived for exactly this reason-they were safer than some treatments simply because they had no effect other than a placebo effect.
A recent paper provides another reason to be skeptical of traditional treatments. In this paper, the authors have developed a mathematical model to show how medical treatments can spread in populations. They included variables for the efficacy of the treatment, conversion and abandonment rates for the treatment, death rate due to the disease, and other variables. When they ran the calculations, they found that ineffective treatments were often more culturally fit than effective treatments. The main reason for this is that an ineffective treatment is often demonstrated more frequently than an effective treatment. This results in a larger number of people adopting the treatment, even if many of them later abandon it. In many cases the recruitment rate was much greater for ineffective treatments and the ineffective treatments had a greater cultural fitness than effective treatments.
This model is very interesting in that it shows how ineffective treatments can develop and persist in a population often better than effective treatments do. This is not earthshaking news to skeptics, and the model does not take into account other factors such as tradition or religious ideas that can also help ineffective treatments to survive. Herbal medicines are one of the most plausible traditional medical treatments, and some traditional herbs have been developed into modern medicines (aspirin is a good example). This model shows why even plausible treatments such as traditional herbs need to be evaluated scientifically before being accepted as an effective treatment. People are likely to favor ineffective treatments. The authors were able to apply their model to both human and veterinary treatments, and even self treatment by non-human primates.

Wednesday, April 8, 2009

I saw this press release today about genistein, a compound found in soy that has been promoted as a supplement that can prevent and treat cancer. A couple of red flags came up for me in the press release such as this;
The researchers found that a commercially available form of genistein called GCP was effective in killing canine lymphoid cells in a laboratory setting, and that GCP is "bioavailable" in canines - meaning it is absorbed into the bloodstream where it can affect cancer cells in the body. The researchers hope that their findings will lead to the use of GCP for their canine patients in conjunction with traditional cancer treatments like chemotherapy.
This by itself sounds OK, but it does not mean that the concentrations of the compound which killed the cancer cells in vitro are safe or even achievable in dogs or humans. Then comes a claim that humans use genistein as a complementary cancer therapy;
"Humans have been using soy in conjunction with traditional chemotherapy for some time as a chemo potentiator," Suter says. "This means that the GCP makes the chemotherapy work more efficiently and faster, which translates to less stress on the patient and less money spent on chemotherapy."
That is a huge leap from killing cells in a petri dish, and is not substantiated by much evidence. Indeed Genistein is know to have estrogenic effects and may actually make certain types of cancer, especially breast cancer grow more quickly.

Finally the biggest red flag in the entire press release was the last paragraph;

"Since GCP is a dietary supplement, it is harmless to patients," he adds. "Plus it's inexpensive and easy to administer in a pill form. There's really no downside here."
A product such as this is not harmless to patients, and saying so could be dangerous to patients, human or animal, who have estrogen responsive tumors. There most definitely is a downside. They have also not established any toxic effects in living animals or humans of the concentrations required to kill canine lymphoma cells.

The paper this press release is referring to was published in the February 15, 2009 issue of Clinical Cancer Research. This paper is a report of a preliminary study of Genistein that was evaluating it's effect on one specific cell type, and they were unable to achieve high enough concentrations in dogs in a 72-hour dose escalation study. The study showed a potential effect for the compound for certain cancers, but there is still a long way to go before the correct dosage is identified and genestein is proven to be a safe and effective treatment. The author's conclusions were much more modest and reasonable than the press release indicated;

The results of these studies support the notion that canine high-grade B-cell lymphoma may represent a relevant large animal model of human non-Hodgkin's lymphoma to investigate the utility of GCP in chemopreventive and/or treatment strategies that may serve as a prelude to human clinical lymphoma trials.

The press release is misleading and could be dangerous if people read it and decide that this over-the-counter product is completely safe and useful for treating or preventing any type of cancer. This is an excellent example of why dietary supplements should be regulated similarly to drugs, and not declared "harmless".

Tuesday, April 7, 2009

Hot Chicks

New Americauna chicks to keep our backyard flock going. These will lay green-shelled eggs starting in 6 months or so. They will also keep our grasshoppers and dandelions under control this summer.

Saturday, April 4, 2009

What is CAM?

Complementary, Alternative, or Integrative medicine (human or veterinary) is not one particular modality or treatment. There are many treatment methods which fall under these classifications.
Ideally, there is only medicine which has been shown to be effective scientifically, and that which has not. Veterinarians tend to use more treatments that have not been proven effective by well controlled clinical trials than are used in human medicine for a variety of reasons. These reasons include research limitations-there is much less money for veterinary medical research than for human medical research-the wide variety of different species veterinarians treat, and the financial limitations of animal owners. Since veterinary critics of alternative medicine are often criticized for using treatments that are not completely proven while attacking other unproven therapies, I will define complementary, alternative or integrative medicine as treatments that may require drastic changes in what is known about science to even work (improbable or impossible mechanism of action), treatments that may possibly have an effect but have not ever been tested or shown to be effective, and treatments that may have been proven, but are often co-opted by unscrupulous practitioners to either give themselves more credibility or take the treatment and exaggerate or twist it into something which is different than it was.
Of course, there is a wide spectrum of alternative therapies which range from completely ridiculous and improbable treatments such as homeopathy or therapeutic touch, treatments like acupuncture or chiropractic which might possibly have a physiologic effect but have still not been proven, to things like physical therapy, nutrition, exercise and vitamin supplementation that are part of any 'definition of medicine but are often claimed or abused by "alternative" practitioners. Some red flags for unproven therapies can include claims that the effect cannot be measured by scientific methods, large amounts of testimonials and/or anecdotal evidence, appeals to antiquity ("acupuncture has been used for 3000 years") claims that the treatment can only be explained by quantum mechanics, or claims that their treatment is being suppressed by some sort of conspiracy by big pharma and organized medicine.
Some of the people who practice these types of unproven treatments honestly believe that they work, and some are just out to make as much money as possible from gullible patients. In either case, it is unethical for a veterinarian and unfair to our patients to subject them to treatments that probably or definitely do not work. It is equally unethical to charge for such services and to encourage delusions that the pet is benefiting from them. Sometimes such delusions can lead to great harm and unnecessary suffering. Since veterinary patients are not able to choose for themselves, veterinarians have an added responsibility to advocate for their patients and to discourage treatments that are unproven, ineffective and potentially harmful.

Thursday, April 2, 2009

Introductory post

When I graduated from veterinary school nearly 20 years ago, there was no "training" in alternative medicine for veterinary students. Very few licensed veterinarians practiced things such as acupuncture, herbal medicine, therapeutic touch or chiropractic. In the time since I graduated, many veterinarians have "integrated" some of these modalities into their practices, with at least the silent acquiescence of their state veterinary boards. This blog is intended to examine alternative practices in veterinary medicine and the evidence (or lack of evidence) for them.
There may be occasional rants and there will be posts on other topics such as vaccinations in veterinary medicine and the sometimes bizarre claims made about them, interesting occurrences in biology, cryptozoology and the conflict between faith and science and evidence.

I hope you enjoy the ride.