CLASSIFICATION OF DISEASES. 97 



Give the aetiology of osteomalacia. 



This disease is rarely seen in the equine race, being more 

 commonly met with among bovines. 



It is seen among animals in zoological gardens, and more es- 

 pecially among pregnant animals and those giving milk. The more 

 abundant the lacteal secretion, the more rapid the course. 



It is a disease of adult life, and may be due to a lack of the 

 proper amount of salts in the food. It may be seen during dry 

 seasons, when the ground is dry, there not being sufficient moisture 

 to dissolve the salts. The want of lime salts in the soil; such as 

 swampy, turfy, or sandy soils, poor in phosphoric acid. 



Three theories have been advanced: 



1st. Where the animals do not receive these elements in their 

 food. 



2d. The acid theory, which says that lactic acid is formed in 

 the stomach and dissolves the salts. 



3d. The inflammatory theory — that an inflammation of the 

 periosteum and bone substance takes place. 



The first is probably the best, as the disease can be produced 

 artificially by giving food not containing these salts. 



What are the symptoms ? 



The first symptom noticed is called pica (hunger, depraved 

 appetite). These animals eat foreign bodies, such as sticks, straw, 

 etc.; they lick the attendant's clothes, or they lick the walls, 

 especially if they have been whitewashed. 



If the disease is allowed to go on, there is trouble in locomo- 

 tion; the animal is stiff, and in walking the legs become more or 

 less entangled by the animal crossing them, and a cracking and 

 snapping of the Joints is often heard. Percussion over the bones 

 gives a clear and hollow sound. 



The articulations are hot, swollen, and painful; the animal 

 does not stand still, but is constantly moving. 



These animals seem to prefer lying down, and it is often dif- 

 ficult for them to get up, evincing pain when they do. Efforts 

 at micturition and defecation cause pain. 



At first there is no fever, but later there is often a slight 

 rise in temperature, the pulse becomes increased, and emaciation 

 is well marked. 



•The ligaments binding the joints may become loosened from 

 their attachments or may become absorbed, and dislocation or 



