PRINCIPLES OF VETERINARY SURGERY 643 



dimensions of the medullary canal, and that the exostoses 

 are deposited at the surface above the periosteum without 

 apparently sinking below it. The radiograph of a trans- 

 verse section, three millimeters thick, made at the upper 

 part of the metacarpus is especially demonstrative on this 

 point. These characteristics do not justify the confusion 

 of this disease with rachitis. In the latter there are defor- 

 mations of the original bone and grave deteriorations of the 

 cartilage of conjugation, which ultimately substitutes a 

 peculiar osteitic tissue in lieu of bone. 



What is the nature of diffuse osteoperiostitis? Only 

 hypotheses can be advanced on the subject. It has been 

 compared to osteitis deformans, or Paget's disease of man. 

 This disease, which has sometimes been regarded as being 

 an appendage to chronic rheumatism, and of acid dyscrasias, 

 is today usually regarded as the consequence of trophic dis- 

 turbances of the nervous system. No investigations have 

 been made in the dog to establish the relations of diffuse 

 osteoperiostitis with a nervous lesion. 



TREATMENT. — No effective treatment is known. 



ACHONDROPLASIA IN THE CALF. 



In human pathology the word "achondroplasia" is ap- 

 plied to an affection of the foetal osseous tissue, manifesting 

 itself by the arrest of the development of the long bones. 

 The existence of the disease in animals has already been 

 mentioned, but its origin still remains a mystery. It is sup- 

 posed to be a dystrophia of enchondral ossification, refer- 

 ence to which will be made in the following description. 



HISTORY. — Before the present era, achondroplasia 

 was not known by its proper name in veterinary pathology. 

 Animals affected with the disease were described as bull- 

 dog calves, or turtle-calves, on account of their rather vague 

 resemblance to these animals. The disease has attracted 



