A new study finds that the animal known as man's best friend can also be a good friend to the heart. Researchers in California say they have found that even just a short visit with a dog helped ease the worries of heart patients. The study divided the patients into three groups. In Group A, a dog and a person visited each patient for twelve minutes. Patients in Group B received just a human visitor for twelve minutes. And members of Group C received no visitor, human or canine . The dogs would lie on the hospital bed so the heart patients could touch them. The researchers say some patients immediately smiled and talked to the dog and the human visitor. Dogs, in her words, "make people happier, calmer and feel more loved." The researchers examined the patients before, during and after the visits. They measured stress levels based on blood flow and heart activity. They say they found a twenty-four percent decrease in the group visited by both a dog and a person. They reported a ten percent decrease in the group visited by a person only. There was no change in the patients without any visit. These patients, however, did have an increase in their production of the hormone epinephrine (epinephrine). The body produces epinephrine during times of stress. The increase was an average of seven percent. But the study found that patients who spent time with a dog had a seventeen percent drop in their levels of epinephrine. Patients visited by a human but not a dog also had a decrease, but only two percent. From the research findings we may conclude that   _  .
the less the body produces epinephrine, the better the longer a visit lasts, the happier the patient should be the patients enjoyed the dogs' company more than the human visitors' it's impossible for heart patients to recover without dogs' visits