CLASSIFICATION OF DISEASES. 99 



it or it may become developed very shortly after birth; the salts 

 have not been deposited. 



Rickets is met with in young foals, high-bred dogs, in calves, 

 lambs, pigs, and among wild animals born in confinement. 



It may be caused by improper nourishment while in utero, 

 or after birth where only allowed to suck once or twice a day, or 

 where the food does not contain the necessary variety and quantity 

 of the proximate principles. 



What is the morbid anatomy ? 



* This is not a local disease of the bones of the extremities, as 

 many imagine, but may and does affect all the bones of the body, 

 as well as other tissues. 



The bones show the most important changes, especially the 

 long bones at their extremities. 



There is an irregularity of the line of ossification, which is 

 more spongy and vascular. The periosteum, which is thickened, 

 strips off and displays a spongoid tissue. These changes cause a de- 

 lay of ossification, so that the bones are not so firm and do not grow 

 so rapidly. Chemically, the calcareous salts show a diminution, 

 in some cases of twenty-five to thirty-five per cent. 



The spleen and liver enlarge. 



What are the symptoms ? 



The bones are soft, the articulations swollen, which causes 

 them to change their shape wherever pressure is brought to bear; 

 the bones of the extremities bend under the weight of the body, 

 giving the names of hoiv-legged, l-noc'k-kneed, cow-liocked, pigeon- 

 toed, according to the location of the condition. 



The pelvis often becomes narrow, the spine twisted or 

 curved. If it curves downward it is called lordosis, or saddle- 

 haclc; if curved upward, kyphosis, carp-dacl-, or roach-bacl-; if side- 

 curving, scoUasis. The breast-bone may become prominent, when 

 it receives the name of cJiicJcen-hreasted. The ribs bulge out, and 

 enlargements are seen at the junction of the false and true ribs; 

 the abdomen is thus prominent, the name of pot-gut being given 

 to this condition. 



There is an impaired appetite and digestion, slight fever, pain 

 on motion or pressure, inability to walk in some cases, emaciation, 

 delayed dentition, the teeth being irregular, muscles are soft and 

 weak, mucous membranes pale, flatulency, diarrhoea in some cases, 

 and at tir^ies nervous symptoms appear, the animal being uneasy. 



