This luxation is also found as a purely accidental occurrence in animals which have suffered from falls and from slipping of the hind limbs backwards or sidewards, as occasionally follows awkward leaping movements. The slipping outwards of the limbs, which causes this form of luxation, is comparatively easy, because of the absence of the pubio-femoral ligament. The accident may also be followed merely by subluxation, that is to say, tearing of the inner portion of the capsular ligament and rupture of some portion of the adductor muscles of the thigh without rupture of the interosseous fibres, the head of the femur not quitting the cotyloid cavity. This accident occurs in stables with smooth, slippery floors, and in railway trucks. It may affect one side or both. The latter condition is exceptional. Finally, luxation may be either complete (in which case the capsular and interosseous ligaments are both ruptured) or incomplete. In the former case, the head of the femur becomes displaced upwards and forwards towards the great sciatic notch, more rarely backwards in the direction of the ischium, and in exceptional cases downwards and inwards below the pubis into the foramen ovale. =Symptoms.= The symptoms vary, depending on whether the luxation is of the spontaneous, progressive order or, on the contrary, is accidental. In progressive luxation, the animals are able to rise and walk with difficulty. The affected limb swings when the animal is advancing, not as though it were paralysed, but simply as though displaced at its upper part. Pain is exhibited when weight is placed on the limb, and there is difficulty in movement. The limb appears shorter than its neighbour when the animal stands on it, and the prominence representing the trochanter is more marked. When a false joint has formed, the limb is rigid, is moved stiffly and abducted, and the stride is shortened. [Illustration: $1] In accidental luxations, either of one or both limbs, the attitude assumed by the animal is often characteristic. One of the limbs is extended at right angles to the longitudinal axis of the body, and sometimes both limbs assume this position, an attitude which would be absolutely impossible under normal conditions. The animal cannot rise. It lifts the front part of the body by rising on its knees, but the hind quarters do not follow. The ruptured adductor muscles are unable to bring and hold the limb parallel to the longitudinal axis of the body; the abductors act unopposed, and at the moment when the animal makes its greatest effort to rise the limb (or limbs) is carried outwards and the body comes to the ground on the udder or groin.