126 



Hereditary Diseases of Horses, 



Hydrocephalus, or water in the head, in one of its forms, is a 

 tuberculous inflammation of the internal serous membranes of 

 the brain. It is ushered in bj languor, disordered digestion, 

 irregularity of the bowels, and a falling off in condition. The 

 limbs become weak and tottering ; the head is hot and tender, 

 and held in a dependent position ; the eyes are impatient of light, 

 and the pupils partially closed ; there is more or less fever and 

 an accelerated pulse. These symptoms, indicative of active in- 

 flammation, give way, after a variable time, to others significant 

 of effusion and pressure on the brain. All the external percep- 

 tions become blunted, and the pulse is slow. As the fluid accu- 

 mulates, the head enlarges, and the bones become soft and thin. 

 This state of depression usually continues until death. The disease 

 is one of early life ; it is rarely met with in animals of more than 

 six months or a year old. As has been already remarked, it is 

 sometimes congenital, and, in such cases, there is usually a great 

 increase in the size of the head, from the amount of the effusion 

 and the soft, yielding nature of the cranial bones. Tbe sub- 

 stance of the brain is found, on examination, to be expanded by 

 the contained fluid, and soft and infiltrated with a thin serosity. 

 The membranes of the brain are much inflamed, coated with 

 lymph, and studded with granules and tubercles, which are also 

 found in other parts of the body, especially in the mesenteric 

 glands, and are in all respects identical with those found in the 

 lungs of consumptive patients. These facts establish the scro- 

 fulous nature of the disease, and its close connexion with con- 

 sumption. 



Tabes Mesenterica is more common in foals than is generally 

 supposed : it occurs at various ages, but seldom affects animals 

 more than two years old. The matter of tubercle is deposited in 

 the mesenteric glands ; and this, interfering with their functions 

 and preventing the due elaboration of the chyle, speedily causes 

 derangement of digestion, imperfect assimilation, and conse- 

 quently rapid wasting and death from inanition. Apparent 

 recoveries occasionally take place, the tubercular matter becoming 

 cheesy, hard, and gritty ; but as the lungs also are usually 

 diseased, recovery is often only temporary, and the animal by 

 and by dies either of phthisis pulmonalis, or of glanders. 



We have noticed that variety of consumption affecting the 

 limbs, or rickets ; that variety affecting the contents of the 

 cranial cavity, or hydrocephalus ; that variety affecting the ab- 

 dominal cavity, or tabes mesenterica; and have now to notice 

 that variety, perhaps, of all the most common and fatal, and 

 which has its seat in the lungs ; this is pulmonary consumption, 

 or phthisis pulmonalis. It consists in a deposition of tubercular 



