spavin. 999 



turning round in the stall towards the sound side. This usually 

 disappears with work. The disappearance of lameness during 

 movement, and its regular recurrence after rest, form one of the most 

 important peculiarities of the disease. The fact that turning towards 

 the sound side seems more painful than towards the diseased is 

 explained by the pressure on the inner part of the hock being then 

 greater. Occasionally, however, cases occur in which the lameness 

 persists during movement, and may, indeed, become more severe, 

 and the hock may show little if any enlargement ("occult spavin"). 

 The increase in lameness when turning in small circles is clearly due 

 to the rotary movement in the limb and the tendency to displacement 

 of the bones in the affected section of the joint. 



The " spavin test " consists in lifting the limb and keeping the 

 hock-joint flexed for one minute and then trotting the horse. 

 Lameness may be very marked for a few steps. This test, however, 

 requires to be used with considerable care, especially in old horses, 

 which may show similar difficulty in movement after the limb has 

 been kept bent, even without having spavin. 



Various hypotheses have from time to time been advanced as to 

 the immediate cause of lameness. Whilst the older practitioners 

 considered the pain to be due to pressure of the exostosis on the 

 periosteum, and supported their view by reference to the uneven 

 surface of the macerated bones, we have known since Havemann's 

 time that the changes within the joint are not only the essence 

 of the disease, but also the cause of the lameness. Though Hering 

 opposed this, stating that spavin lameness is sometimes seen without 

 disease of the joint, either his observations were due to errors in 

 diagnosis, or the process was only in a developmental stage, the articular 

 surface not yet having suffered. As a rule, the onset and course 

 of the lameness entirely agree with the observations made in men 

 suffering from arthritis chronica, who at first only show lameness 

 for a few steps. The lameness is probably due to changes partly 

 in the articular surfaces, partly in the ligaments. Dieckerhoff adds 

 disease of the bursa of the flexor metatarsi muscle. It seems 

 doubtful whether chronic inflammation of this bursa ever produces 

 lameness. 



(2) The exostosis may even precede the lameness in cases where 

 the disease develops slowly : as a rule, the two appear simultaneously, 

 but sometimes the bony swelling does not occur until many weeks 

 afterwards. Its detection requires an accurate knowledge of the 

 normal configuration of the hock-joint, and may be effected by 

 viewing the joint either from the front or back. For this purpose 



