"A therapyanimal trend grips the United States. The San Francisco airport now deploys a pig https to calm frazzled travelers. Universities nationwide bring dogs and a donkey https onto campus to soothe students during finals. Llamas comfort hospital patients http pooches provide succor at disaster sites http_befcfcbfcdbbcf.htmlmodejqm and horses are used https to treat sex addiction. And that duck on a plane https_term.badadc It might be an emotionalsupport animal prescribed by a mental health professional. The trend which has accelerated hugely since its initial stirrings a few decades ago is underpinned by a widespread belief that interaction with animals can reduce distress  whether it happens over brief caresses at the airport or in longterm relationships at home. Certainly the groups offering up pets think this as do some mental health professionals. But the popular embrace of pets as furry therapists is causing growing discomfort among some researchers in the field who say it has raced far ahead of scientific evidence. Earlier this year in the Journal of Applied Developmental Science an introduction to a series of articles on animalassisted intervention said research into its efficacy http remains in its infancy. A recent literature review httponlinelibrary.wiley.comdoi.jclp.abstract by Molly Crossman a Yale University doctoral candidate who recently wrapped up one study involving an yearold dog named Pardner cited a murky body of evidence that sometimes has shown positive shortterm effects often found no effect and occasionally identified higher rates of distress. Overall Crossman wrote animals seem to be helpful in a smalltomedium way but its unclear whether the critters deserve the credit or something else is at play. Its 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 said James Serpell director of the Center for the Interaction of Animals and Society at the University of Pennsylvania School of Veterinary Medicine. That kind of thing has almost driven the field and the research is playing catchup. In other words people are recognizing that anecdote isnt enough. Using animals in mental health settings is nothing new. In the th century a Quakerrun retreat in England encouraged mentally ill patients to interact with animals on its grounds. Sigmund Freud often included one of his dogs in psychoanalysis sessions. Yet the subject did not become a research target until the American child psychologist Boris Levinson began writing in the s about the positive effect his dog Jingles had on patients. But the evidence to date is problematic according to Crossmans review and others before it. Most studies had small sample sizes she wrote and an alarming number did not control for other possible reasons for a changed stress level such as interaction with the animals human handler. Studies also tend to generalize across animals she noted If participants are measurably soothed by one golden retriever that doesnt mean another dog  or another species  will evoke the same response. Even so media headlines are often about the happiness bounce. Hal Herzog a Western Carolina University psychologist who has long studied humananimal interactions recalls a  study on the health benefits for children of having a pet dog. Heres a reason to get a puppy NBC announced. http Kids with pets have less anxiety. Thats actually not what the study concluded. The authors did find that children with dogs had lower anxiety based on screening scores than children without dogs. Still they cautioned that this study does not answer whether pet dogs have direct effects on childrens mental health or whether other factors associated with acquisition of a pet dog benefit their mental health. It was a classic case of conflating correlation and causation which Herzog says is common. Cherrypicked positive results also are a problem as he says happens in promotional materials from the HumanAnimal Bond Research Initiative HABRI. The petindustry backed httpshabri.orgsupporters organization funds research on the topic. The number of papers I see that start out It is now wellestablished that there are health benefits from owning pets  that drives me crazy Herzog said. Yes theres literature that supports that. But theres also literature that doesnt find that. Children interact with Gypsy during the miniature horses visit to Nemours Childrens Specialty Care in Jacksonville Fla. Bob MackThe Florida TimesUnion via AP  HABRI Executive Director Steven Feldman takes a more positive view of the science while acknowledging that more research needs to be done. Just like getting vegetables and getting exercise I would say having animals in our lives is also an essential element of human wellness he said. To many animal lovers and pet owners the backandforth might sound horribly wonky. Theres something intuitive about the good feelings animals give us. Why overanalyze it Alan Beck does not disagree. Beck who directs the Center of the HumanAnimal Bond at Purdue University cites one common theory for why animals might be therapeutic. Its called the biophilia hypothesis and it argues that humans evolved a builtin need to affiliate with other living beings. Throughout history animals gave us some comfort. So if it works for you and me in a relatively normal environment maybe it has a special role for someone who has a depression and stress disorder  that just makes sense he said. The literature does show its not bad. And thats just as important. Focusing too much on scientific support sometimes feels like a form of physics envy httpsen.wikipedia.orgwikiPhysics_envy Beck added where you try to quantify everything without appreciating it. But there are good reasons for rigorous research on animals and mental health. In  the Department of Veterans Affairs said it would not cover https costs of service dogs for veterans with posttraumatic stress disorder citing a lack of evidence to support a finding of mental health service dog efficacy. The department is now in the midst of a multiyear study on the topic which could lead to government funding for these pooches. Another reason the scientists say is for the animals sake. Crossman pointed to a  incident at Washington University in St. Louis as an example of animal therapy gone wrong. A bear cub brought to campus http during finals week nipped some students causing a rabies scare that almost ended with the animal being euthanized. More generally Serpell said the popular idea that pets make you happier is not a harmless distortion.  If the public believes that getting an animal is going to be good for them many times an unsuitable person will get an unsuitable animal and it doesnt work out well for either. A facility in Spain uses dogs to help those with intellectual disabilities and mental health conditions. The research is getting stronger in part because funding is growing  from HABRI as well as from a publicprivate partnership https between the National Institutes of Health and the Waltham Centre for Pet Nutrition. Crossmans recent study at the Yale Innovative Interactions Lab httpiilab.yale.edu was among the work being supported. It relied not just on the Labrador retriever Pardner but seven other certified therapy dogs httpiilab.yale.edulabmembersanimals. Several times a month over much of the past year they hung out at the university for minute sessions with children who had just finished two stressful tasks spontaneously crafting stories and telling them to strangers followed by doing math problems. The strangers were the researchers and their mission was to assess whether the kids ages  to  would find their time with the dogs to be therapeutic. The study was designed to avoid some of the pitfalls that Crossman has seen elsewhere which is why some of the  young participants got to play only with a fuzzy blanket  because tactile stimulation is known to reduce stress  and why others simply waited for the  minutes. Without the controls the changes could be due to all kinds of things like the fact that lots of time has passed Crossman said. Kids are actually pretty good at coping. The children completed questionnaires to assess their mood and anxiety before and after spit samples to measure the stress hormone cortisol were taken at three points. At the end all the kids got a junior scientist certificate lots of praise and an open play session with the dogs. Crossman who emphasizes that she is an animal lover declined to reveal the findings before theyre published. But hopefully they will show that dogs can affect childrens stress she said  before quickly offering a researchers clarification. I say hopefully not just because I think it works or hope it does but because these programs are used so widely she explained. Kids are already participating in this on a huge scale. Ideally the order goes the other way around We test the idea and then we implement."