80 
Hereditary Diseases of Cattle. 
appearance. The skin is liaid and dry, and ■wants that soft 
pliancy so characteristic of health ; the roots of the hair are 
hidden by a dirty brown scurf. The appetite is caj)ricious, and 
rumination irregular. In milk-cows the lacteal secretion is 
diminished in quantity, and is "generally very thin and blue; a 
cough soon appears, at first loud, free, and distinct, and per- 
formed without much appearance of pain, but afterwards frequent, 
hoarse, and indistinct, preceded by several quick deep inspira- 
tions, and succeeded by blowing and panting ; and at a still later 
stage rough gurgling, and very frequent, painful, and exhausting. 
As the severity of the disease increases, the respirations become 
more and more accelerated and laboured. After a time the pulse 
is also quickened, being usually about seventy beats per minute, 
but very soft and compressible. A speedy fatal termination is 
usually indicated by an increase of the hectic fever, great debility, a 
muco-purulent discharge from the nostrils, the appearance of 
dropsical effusions in the limbs and tlie various dependent parts 
of the body, and the existence of diarrhaa or dysentery. The 
legs, ears, and mouth are alternately hot and cold, and the eyes 
are sunk, glassy, white, and bloodless — this last appearance depend- 
ing upon the diminished quantity and vitiated quality of the blood 
in the system. These symptoms of pulmonary consumption are the 
external signs of certain internal changes to which we must now 
briefly advert. The disease consists in the development in the 
blood of tubercular matter, and its deposition in various parts of 
the body, chiefly in the lungs. This tubercular matter, as at first 
deposited, is of a cheesy, fibrinous, and gluey nature, consisting of 
degenerated lymph and albumen. By and by part of the organic 
matter is reabsorbed, but fresh deposits are also continually being 
made, and these after a time contain more or less calcareous matter. 
The tubercles so formed soon produce irritation and ulcerative 
inflammation, thus giving rise to cough, fever, and occasionally to 
secretion of pus, which however does not occur in cattle so com- 
monly, or to such an extent, as in man. The tubercles are some- 
times scattered over the whole substance of the lungs, sometimes 
aggregated together. They are generally found in largest number 
in the upper and posterior parts of the left lung, being exactly 
the opposite of what obtains in the case of inflammation, which 
attacks more frequently and with greater severity the lower por- 
tions of the riglit lung. The lungs are more often, and to a 
greater extent, the seat of tuberculous deposits than any other 
part of the body. This results from every particle of the blood 
passing through them, from the fineness of their capillary blood- 
vessels, their soft and easily compressible structure, their (sup- 
posed) function of elaborating the fibrine, and their exposure to 
atmospheric influences of a deleterious nature. Other parts are, 
