(LAMENESS IN THE HIND LEG 239 



toms 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 exist- 

 ence 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 immedi- 

 ately at a trot. During the first few steps taken directly there- 

 after, 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 ex- 

 toses form even during the course of years. The spavin test is 

 of aid in establishing a diagnosis here but the marked "warm- 

 ing out" peculiar to spavin is not so pronounced in such cases. 



Prognosis. — An animal having hereditary predisposition to 

 spavin is not likely to recover completely whether this predis- 

 position be due to faulty conformation or susceptibility to bone 

 changes. In predicting the outcome, the temperament of the 

 subject is to be taken into account, as well as the character of 

 service the animal is expected to perform. And finally, a very 

 important feature to be noted, is the location of the exostosis. 

 If situated rather high and extending anterior to the hock, there 

 is less likelihood of recovery resulting than where an exostosis 

 is confined to the lower row of tarsal bones. When situated 

 anterior to the tarsus a large exostosis may by mechanical inter- 

 ference to function, cause lameness when all other causes are 



