Spavin lameness is so distinctive that one trained and experienced in the examination of horses that are spavined, should correctly diagnose the condition in practically every instance without recourse to other means than noting the peculiar character of the gait of the subject. Lameness develops gradually in the majority of instances, and an important feature in spavin lameness is that it disappears after the subject has gone a little way, to return again as soon as the animal has rested for a variable length of time--from a half hour to several hours. This "warming out" is marked during the incipient stage, but less pronounced in most chronic cases. A complete disappearance of lameness is observed in some instances, while in others only partial subsidence is evident. Because of the fact that pain is occasioned both during weight bearing and while the leg is being flexed and advanced, there is manifested the characteristic mixed lameness and exaggerated hip action which typifies spavin. By throwing the hips upward with the sound member it is possible to advance the affected leg with less flexion, hence less pain is experienced in this manner of locomotion. When made to step aside in the stall, a spavined horse will flex the affected member abruptly and when weight is taken on the diseased leg, symptoms are evinced of pain, and weight is immediately shifted to the sound limb. This is marked during the incipient stages of spavin. Lameness usually precedes the formation of exostosis, though cases are observed wherein an exostosis is present and no lameness is manifested and no history of the previous existence of lameness is available. The "spavin test" is of value as a diagnostic measure when it is employed with other means of examination, though reaction to this test is seen in some cases in old "crampy" horses that have experienced hard service. The test consists in flexing the affected leg (elevating the foot from the ground twelve to twenty-four inches) and holding the member in this position for a minute, whereupon the animal is made to step away immediately at a trot. During the first few steps taken directly thereafter, the subject shows pronounced lameness and this constitutes a reaction to the spavin test. Where no exostosis is present it becomes necessary to exclude other causes for lameness but the characteristic spavin lameness is to be relied upon to a greater extent in such cases than are other means of examination. Such cases are known as occult spavin and may be present for months before any external changes in structure are observable. In some instances no extoses form even during the course of years. The spavin test is of aid in establishing a diagnosis here but the marked "warming out" peculiar to spavin is not so pronounced in such cases.