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Vet Defends Placebo Effect on Dogs

Owners' expectations and observations may be responsible for a placebo effect in dogs.

Q. A letter writer who suggested that a “placebo effect” is not possible with dogs was mistaken. The person had used a bar of soap under the dog’s bed to treat arthritis.

There is a very large placebo effect documented from placebo-controlled clinical trials in dogs. This effect can reach 30 or 40 percent or higher.

It is caused by either the pet owner or the veterinarian having a perceived belief that the dog’s condition has improved. As a veterinarian, I suspect that the owner in this instance observed a placebo effect, since a bar of soap has never been shown to be effective in a well-conducted trial in humans.

A. You may very well be right. We have not seen any trials of soap under the sheets, well-conducted or not, so we would have to say this approach remains untested.

There are many readers who have conducted their own personal trials of soap under the bottom sheet to prevent leg cramps, calm restless legs or provide non-drug pain relief. While none of these are scientific studies, they suggest that this simple remedy might be worth a try. It meets our criteria: It won’t hurt, might help and doesn’t cost too much. While the results may be attributable to a placebo effect, that might not be a problem in some cases.

Ann in Washington offered her experience:

“I have been using bars of soap for some time.  I think the idea came from you years ago.

“I now use bars of soap on my hands and fingers that cramp up on me during the day. I have been hunting on the internet trying to find out what is in the soap, because I think it will work on any part of the body. If I hold something in my hand too long, it begins to cramp up and so sometimes I use a bar of soap if I am writing on paper or sometimes holding a book or magazine.

“I carry a bar of soap in my purse all the time, because sometimes when I am grocery shopping and handling different items, my hand will suddenly start cramping. The doctors think that I am crazy when I have mentioned what I do.”

We don’t know which ingredients may be relevant. Dr. Yon Doo Ough has done some research on the fragrance used in soap (Journal of Multidisciplinary Healthcare, Sept. 2008).

Some people report, however, that fragrance-free soap is also helpful, as Donnie found:

“I have two different brands of soap that I have tried for cramps, etc. Both of them work, and both are all natural and fragrance free.

“I use small pieces of bar soap when they get too small to use in the shower. I put the soap scrap in an old sock before putting it under my sheet. And I stick it into my sock if I have a leg cramp when I’m not in bed.”

Our People’s Pharmacy Bed Soap contains:

  • Sodium palmate (saponified palm oil)
  • Sodium cocoate (saponified coconut oil)
  • Water
  • Glycerin
  • Lavender essential oil
  • Fragrance
  • Vitamin D
  • Rosemary leaf extract
  • Violet 2 (color)

We have observed that veterinary research is frequently ahead of human clinical trials, perhaps because it is slightly less expensive to conduct. We’d love to see some well-conducted veterinary research on whether exposure to any of these ingredients has the ability to relax muscles or alleviate symptoms of pain in dogs or other creatures.


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About the Author
Joe Graedon is a pharmacologist who has dedicated his career to making drug information understandable to consumers. His best-selling book, The People’s Pharmacy, was published in 1976 and led to a syndicated newspaper column, syndicated public radio show and web site. In 2006, Long Island University awarded him an honorary doctorate as “one of the country's leading drug experts for the consumer.”.
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