HEREDITARY DISEASES OF HORSES. 
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variable time, to others significant of effusion and pressure 
on the brain. All the external perceptions become blunted, 
and the pulse is slow. As the fluid accumulates, 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 re- 
marked, 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. The substance 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 con- 
sumptive patients. These facts establish the scrofulous 
nature of the disease, and its close connection 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, im- 
perfect assimilation, and consequently 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 
abdominal 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 de- 
position of tubercular matter in the lungs ; at first soft and 
cheesy, or gluey and fibrinous, and becoming, after a time, 
hard and gritty, but always unorganisable. Its symptoms 
are irritation of the mucous lining of the bronchia and lungs, 
as evidenced by cough ; occasional febrile symptoms, wasting, 
and debility, which, in bad cases, sets in early, and is so 
excessive as speedily to destroy life. We have treated very 
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