590 PRINCIPLES OF VETERINARY SURGERY 



turn to their normal condition and in others the reaction 

 makes the epiphyses harder. The disease has been observed 

 at birth, that is to say, rachitis may be congenital, and char- 

 acterized by voluminous articular tumefactions which cause 

 dystocia. This special feature is, however, rare. In addition 

 to the special lesions of the skeleton, there is general atrophy 

 of all the tissues and various secondary lesions occurring 

 toward the termination of the disease. 



DIAGNOSIS. — At the beginning, the disease presents 

 no special characteristics and could not be recognized ex- 

 cept by the existence of other cases in animals exposed to 

 the same influences. But when the disease has reached its 

 crisis, it cannot be confounded with any other disease. In- 

 fectious polyarthritis is easily differentiated; its onset is 

 sudden and it is accompanied with intense pyrexia and swell- 

 ings of the articulations, which sometimes suppurate. The 

 differentiations between rachitis and articular rheumatism is 

 equally simple ; the latter has a sudden beginning and is 

 accompanied by a violent reaction that is entirely absent 

 in the former. In colts the disease must not be confounded 

 with osseous or synovial inflammations, nor congenital de- 

 formities. Here a differentiation is made by the shortening 

 of the bones, their incurvations and the enlargement of the 

 epiphyses. 



PROGNOSIS. — The prognosis is always grave. Never- 

 theless, in the beginning, an appropriate course of treatment 

 may ameliorate the condition of the affected subject. When 

 the deformed bones have consolidated the defective posi- 

 tion of the limbs cannot be remedied, and as a result the 

 value of the animal is greatly diminished. The prognosis 

 is, therefore, particularly grave from an economical point 

 of view. 



PATHOLOGICAL ANATOMY.— The degenerative 

 changes of rachitis are essentially osseous lesions. They 



