The student of lameness is interested in the function of the legs in the role of supporting weight and as propelling parts, and not particularly in the capacity of these members for inflicting offense or as weapons of defense. Yet, in the exercise of their functions other than that of locomotive appliances, injury often results, but usually it is the recipient of a blow that suffers the injury, such as an animal may receive upon being kicked. Therefore, we do not often concern ourselves with strains or other injuries that the subject experiences as the result of efforts put forth in kicking or striking. Where such injuries occur, however, a diagnosis is established by making use of the principles heretofore discussed. As propelling members the front legs bear weight and are advanced alternately when the horse is walking or trotting--in cantering this is not so. When the normal subject travels in a straight line, at a walk or a trot, the length of the stride is the same with the right and left members. The stride of the right foot then, for example, is equally divided by the imprint of the left foot, in the normal horse, when traveling at a walk and in a straight line. Shoulder Lameness. This enigmatical term is frequently employed by the diagnostician when he is baffled in the matter of definitely locating the cause of lameness; when he has by exclusion and otherwise arrived at a decision that lameness is "high up." Shoulder lameness may be caused by any one or several of a number of conditions, e.g., fractures of the scapula or humerus; arthritis of the shoulder or elbow joint; luxation of the shoulder or elbow joint (rarely); injuries of muscles and tendons of the region due to strains, contusions or penetrant wounds; paralysis of the brachial plexus or of the prescapular nerve; involvement of lymph glands; arterial thrombosis; metastatic infections; rheumatic disturbances; and as the result of inflammation, infectious or non-infectious occasioned by collar bruises. In some instances such inflammation is due to the manner of treatment of collar injuries. Therefore, when one considers the numerous and dissimilar possible causes of shoulder lameness, it behooves the practitioner to become proficient in diagnostic principles. A principle which is elemental in the diagnosis of locomotory impediment, is that lameness of the shoulder or hip is usually manifested by more or less difficulty in swinging the affected member. Swinging-leg-lameness, then, is usually present in shoulder affections. In some instances lameness is mixed as in joint ailments, involvement of the bicipital bursa (bursa intertubercularis), etc. In affections of the extremity there exists supporting leg lameness. Consequently, we employ this elemental principle, and, by a visual examination of the subject, which is being made to travel suitably, one may decide that lameness is either "high up"--shoulder lameness or, "low down"--of the extremity.