Well why not? Dogs have body's too and they feel pain, discomfort and stiffness just as we do. Although, unlike us that whinge and complain when we're in pain, dogs suffer in silence. When you understand why it's natural for them to do this, it will make more sense to you why they have to do this and why seeking a trained canine therapist is the most loving gift you can give you much loved loyal friend.
Dogs do suffer with silent pain due to muscular tightness, muscle weakness causing imbalances and compensation patterns through their system which can then lead to joint stiffness and joint issues as they age. Just because they don't tell you they're suffering, doesn't mean they don't have pain. Quite the opposite.
Having body tension, tightness and weakness also effects the internal structures of the body like organs and glands causing further the mind - body - spirit to imbalance. Howlistic Healing seeks to balance the whole dog. Not just the body or the mind or the spirit.