I have a love/hate relationship with the placebo effect. On the one hand, I simply want my patients to feel better and don’t really care how that occurs. However, since a large part of the placebo effect in veterinary medicine is related to the primary caretaker’s and veterinarian’s perception of how the animal is doing and not on the patient’s own experience, I worry that the placebo effect leads me to overestimate the success of the treatments I prescribed.
As Margaret Gruen, one of the researchers involved in developing a new study design aimed at teasing out the effects of placebos, put it in a North Carolina State University press release:
In veterinary medicine, we’re one step removed from the patient, and so we run into what we call the ‘caregiver placebo effect,’ which is how we refer to a number of factors that result in unconscious influence on owners’ responses. Merely observing behavior can change it, and any changes in daily routine, like administering medication, will affect the way you relate to that animal and change its behavior.
The study was recently published in the Journal of Veterinary Internal Medicine. Fifty-eight cats with clinical and radiographic evidence of degenerative joint disease (osteoarthritis) were enrolled and divided into two groups. All cats received a placebo during the first two weeks of the study, and their owners were aware of what they were giving. During the next three weeks, one group of cats was switched to a pain reliever while the other group continued with the placebo. Owners were aware that the change had taken place but not which group their cats were in. Finally, all cats again received a placebo for the last three weeks of the study, but the owners did not know that a switch had been made.