Consist in a displacement of the end of a bone from its connexion with the one above it; and they may occur at the hip, stifle, shoulder-joint, or knee, as well as the joints of the toes. The hock is seldom dislocated without fracture, but such an accident has been known to occur, and great trouble would be experienced in its reduction, on account of the shape and nature of the joint. Dislocation of the stifle-joint is not very common, it being very strongly guarded by ligaments, and broad also in the surface of the bones of which it is composed. The hip-joint is very often the seat of dislocation, and is one of the most intractable of all to manage. The socket projects in a prominent manner from the body of the pelvis, and when the head of the thigh bone is thrown out of its cup in sinks at once deeply by the side of it, and can scarcely be drawn out of its bed by any force which can be applied. In the anterior extremity, the knee is the chief seat of this kind of accident, and it is dislocated quite as frequently as the hip, but its reduction is ten times as easy, because both bones can. easily be grasped, and extension being made, they are speedily brought into a proper relative position.

But though they are readily reduced, they are as easily thrown out again; and, therefore, great care is required to prevent this unhappy result. The elbow and the point of the shoulder are seldom put out, because these joints are so securely guarded that the bones of which they are composed are more inclined to break than to leave their sockets. In both the hind and fore-legs the toes are often put out; and, besides this accident, the tendons are apt to give way, causing the accident which is called " the letting down of the toes".

The Treatment of all dislocations consists in putting the displaced bone back again into its socket as speedily as possible, for if allowed to remain long out of its proper situation it contracts fresh adhesions, and can scarcely be drawn away from them by any practicable force. The dislocated knee is reduced simply by pulling steadily the two bones away from one another; an assistant seizing the arm, and the operator making extension by laying hold of the foot and pastern. After it is reduced, a piece of list should be crossed in the form of a figure of eight behind the joint, so as to prevent it from being straightened, and thus again displaced; and this position must be maintained for some time, in order that the torn ligaments may have time to unite. In the dislocated hip, unless very recently done, chloroform should be used, because the muscles of that joint are very powerful and it will require great force to overcome their action without its assistance. The dog is first placed on a table, with a firm cushion under it; chloroform is then administered, by placing a sponge dipped in it in the end of a leather muzzle, such as is used for the greyhound.

The holes at the side should be stopped, by pasting strong paper over them, so as to make a complete cone, one end of which is adapted to the jaws, and the other is closed by the sponge; so that the dog, when it is put on, can only breathe through the sponge. After a short time he snores, and breathes heavily, and then the sponge may be withdrawn for a time, and the attempt made to lift the bone into its socket. I have, however, lately failed, even with the aid of this agent, in reducing a hip dislocated only for about ten days; and I am not aware of any case of more than a few hours' duration where a hip has been replaced. Nevertheless, in a valuable dog, such as that in which I made the attempt, which was a highly-prized puppy, presented to me, and of a very scarce breed, the attempt is worth making, especially as it occasions no pain.