324 



DISEASES OF THE ORGANS OF LOCOMOTION 



of the bones of the whole system, which can easily be distinguished on 

 looking at the animal. It seems to be due to a deficiency of lime-salts 

 in the bones, making them soft and flexil;)le. At the same time the 

 nutritive process in the periosteum seems to be changed. The bones are 

 light and soft enough to cut with a knife, and the epiphyses of the long 

 bones are very much thickened; the marrow and periosteum are reddened. 



When the periosteum is forcibly removed from 

 the bones of the animal in this condition, cer- 

 tain portions of the bony tissue come away 

 and remain attached to the membrane. This 

 is especially noticeable between the epiphyses 

 of the vertebrse. The inner layer of the peri- 

 osteum is thickened and the diseased tissue 

 seems to have undergone a spongy degener- 

 ation. Inside of the bone we find it soft and 

 cavernous. In the normal dog the bones of the 

 skull are joined evenly, but in the rachitic dog 

 interosseous spaces (fontanels) have been 

 found. 



Clinical Symptoms and Course. — Omitting 

 the animals that are born with rickets, the first 

 appearance of rickets is gradual, and generally 

 the veterinarian is not consulted in the early 

 stages, but only when the skeleton shows 

 marked alterations of form, especially the 

 bones of the extremities and back. The ani- 

 mals are dull, walk very carefully and with 

 more or less effort, have no desire to run about, 

 but lie down as long as they can. We find peri- 

 osteal alterations in the frontal bones and 

 bones of the temple, so that the head shows 

 a peculiar marked alteration in conformation. 

 Schutz has found that in rachitic animals the 

 bones of the skull are extremely thin and the 

 sutures separated. In the thorax there is a 

 weakening of the walls of the chest, and the 

 animals present that one-sided or " chicken- 

 chest" condition. There is a peculiar knot-like swelling of the ribs both 

 at their upper extremities where they unite with the vertebrae, and in their 

 inferior extremities where they unite with the sternum and false ribs. 



In this latter condition there forms a series of small, round nodules 

 known as ''rachitic rosary." In acute forms of this disease the spinal 

 cord is twisted or bent in different directions (kyphosis, lordosis or 



Fig. 102. — Radius and ulna of a 

 dog afifected with rickets. 



