Is Your Cat's Medicine Working?

By Jane Farrell

There’s a new clinical design to determine whether medicines designed for cats are actually doing the job.

In designing the new method, researchers from North Carolina State worked to overcome the “placebo effect” in a pain-management study of cats. Evaluating the effectiveness of a medicine is difficult when it comes to cats, who may not reveal the pain they are suffering and who also are resistant to taking medication.

As a result, the effectiveness of medications have been extremely difficult to measure, especially since the owner’s relationship to the cat is another factor that may determine an animal’s response. Additionally, owners may also erroneously perceive their pet’s response.

Not surprisingly, all these factors make veterinary research much more difficult. “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,” says Margaret Gruen, NC State veterinary clinician and researcher. “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. We cannot get away from this, so we need to find a way around it.”

To do so, Gruen and lead researcher Duncan Lascelles tested a low dose of a drug commonly used for pain management in cats with degenerative joint disease. In the first stage, they gave the participants an initial two-week placebo to get the animals used to taking the medication. The owners knew that they were giving a placebo. Then there was a three-week trial with half the cats receiving an actual drug and the rest getting a placebo. The owners didn’t know which group their pet was in. Finally, all the cats were given placebos without the owners knowing.

“The final three-week period is where we were able to get real results about the usefulness of the medication,” Gruen says. “During the three week medication trial, all of the owners indicated that their pets improved, which is due to the caregiver placebo effect. But during the [third] phase, owners of the cats who had been receiving the medication in the first phase said that their pet’s signs of pain were returning, while the owners of cats who had received placebo in the first phase did not notice any change.

“So we were able to circumvent the placebo effect and determine that this medication is effective in cats with degenerative joint disease,” Gruen continues. “We understand that this approach will need further investigation, but we believe this design may be useful both in veterinary studies and in human studies where the placebo effect is particularly strong.”

The study results were published in the Journal of Veterinary Internal Medicine.