INTERNAL DISEASES 411 



which are characteristic of the disease in human children, 

 namely, enlargement of the ends of the bones, bending of the 

 bones, deformity of the spine, etc. Foals and calves are simi- 

 larly affected, and the condition is met with also in artificially 

 fed young beasts in zoological gardens. According to A. 

 Hirsch, rickets is not seen as a disease of children either in 

 Madagascar, Mayotte, or the Archipelago adjacent to these 

 islands. Ebbell, however, states that he has frequently seen the 

 disease during his ten years' stay in Madagascar. 



A disease of the bones which is limited to adult life is 

 osteomalacia, in which a softening of the bony skeleton takes 

 place owing to the abnormal absorption of lime salts, and the 

 replacement of the firm osseous tissues by bone marrow. This 

 disease both in man and animals is limited to the female sex, 

 and generally comes on during pregnancy or after childbirth. 

 It is most frequently seen in cattle, less often in sheep, goats and 

 swine, and least often in mares and bitches. 



Besides rickets and osteomalacia there is a third disease of 

 the bones which occurs both in man and in animals, namely, 

 osteoporosis. Here there is atrophy due to absorption of the 

 bony substance. 



In man this is often a symptom of senility, but under the 

 influence of certain lesions it may occur earlier. It has not yet 

 been observed among wild animals, but it occurs in domestic 

 animals, especially cattle, as the result of insufficient food, and 

 also in animals in captivity in zoological gardens, either as a 

 result of insufficient food or exercise. The so-called giraffe's 

 disease described by Brugsch l may be classed as osteoporosis ; 

 and on this condition depend the frequent spontaneous fractures 

 which occur in zoological gardens among cassowaries, herons, 

 etc., in captivity, when they are handled. 



Diseases of the Nervous System. 



The gross pathological, and anatomical, changes which take 

 place in the brain and spinal cord are the same in domestic 

 animals as in man. From various causes horses, dogs and 

 sheep may suffer from hyperaemia or anaemia of the brain ; 

 chronic hydrocephalus and actual apoplexy may occur in horses, 



1 Zoolog. Garten, 1864, no. 5, p. 129. 



