Scientists conducted a study on 76 heart disease patients. They used three methods: a volunteer to bring a dog to visit the patient, a volunteer to visit the patient and no volunteer to test separately the response of these patients. It was found that in the first case, the patient's anxiety level dropped by 24%, in the second case, the patient's anxiety level only dropped by 10%, and in the third case, the patient's anxiety level remained at the original level. 
Among the volunteers with dogs, the vast majority like and raise their own pet dogs.
 scientists believe that dogs can help people with heart disease to reduce anxiety.