Therapy animals are on trend, everyone is getting some sort of certification so they can take their pets on the plane and into restaurants, but though no one in business wants to mess with mental illness, there is not much evidence they are more than placebo.
Instead of being able to show they really do much to help, a review showed some positive short-term effects, most often found no effect and occasionally identified higher rates of distress. When it comes to pesticides, environmental groups will take such a mishmash and make it only about the negative. Therapists, people selling these animals, and people who just like having their pets around focus on the positive and ignore all of the confounders.
“It’s a field that has been sort of carried forward by the convictions of practitioners” who have seen patients’ mental health improve after working with or adopting animals, James Serpell, director of the Center for the Interaction of Animals and Society at the University of Pennsylvania School of Veterinary Medicine, told Karin Brulliard at Washington Post. “That kind of thing has almost driven the field, and the research is playing catch-up. In other words, people are recognizing that anecdote isn’t enough.”
Like homeopathy, this has survived hundreds of years despite no evidence it works. Like a lot of woo, such as eating placentas and environmentalism, this had a resurgence in the "natural" movement of the 1960s.