Animal studies are complicated by the so-called caregiver placebo effect, but new research has explored a way of controlling for the effect of potentially biased pet owner observations. Veterinarians Duncan Lascelles and Margaret Gruen had success with a three-phase study to circumvent the placebo effect. The first phase involved a placebo for all pets, followed by three weeks in which half the animals were treated with the test medication, then a three-week washout period. "The final three-week period is where we were able to get real results about the usefulness of the medication," Dr. Gruen said.
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