Pets are indeed wonderful therapy, and I think they always help when feeling down, but true clinical depression can be utterly disabling and sometimes medical treatment is truly necessary. It can be medically treated very successfully. I think too often it's viewed as a sign of weakness when someone resorts to medical treatment of depression, or a sign of strength when someone holds back from medical treatment, since it is not often viewed as much of a disorder as diabetes or hypertension. It is not (usually) someone taking a pill in order to be happy, which seems a common misconception.