38 ON MURRAIN^ OR THE VESICULAR EPIZOOTIC. 
disease, do not run into the opposite extreme, and neglect the 
use of measures which have received the sanction of experience. 
Prophylaxis . — The prophylaxis of the vesicular epizootic, or 
the means to be employed for its prevention, requires not only 
an intimate acquaintance with hygienics (that is the knowledge 
and application of the means of preserving health in general), 
but also a special knowledge of the nature, causes, and tenden- 
cies of the particular disease. 
The first step towards the prevention of the disease is, to 
remove every thing inimical to health, every thing which even 
in the slightest degree interferes with the proper fulfilment of 
the functions of life, or impedes the general power and vigour 
of the animal body. The first care must, therefore, be to reform 
the sanitary condition of our domesticated animals. They must 
be provided with abundance of pure, cool, and dry air, and a 
sufficient quantity of digestible and nutritious food. The situa- 
tion and accommodation of byres, courts, sheds, folds, and styes, 
must be consistent with health and comfort; all filth must be 
speedily removed, and fluids likely to prove injurious, from their 
offensive effluvia or from their causing humidity of soil or atmo- 
sphere, must be conveyed away by underground and air-tight 
drains. With especial regard to the vesicular epizootic, care 
must be taken to prevent communication of healthy animals 
with those that are, or have been recently, affected by the 
disease ; means must also be taken to destroy, by the diligent 
employment of disinfectants, the contagious virus by which the 
disease is in great part propagated. 
As this is a very important part of our subject, we shall take 
leave to offer some further remarks in reference to and in illus- 
tration of what we have said above. 
On the purity and sufficiency of the volume of air passing 
through the lungs depend the health of the individual, the due 
aeration of the blood, and the support of the strength and vigour 
of the whole system. Deficient ventilation entails on all living 
animals bad effects more or less striking. Where the evil is in 
continued operation, it slowly and silently, but not the less 
surely, tells on the general health. Air which has passed 
through the lungs is not only deteriorated in quality, but, by its 
temperature being thus increased, it becomes rarefied, so that at 
each inspiration a less amount of oxygen enters the lungs. The 
effect of this is soon perceived on the blood ; it ceases to be duly 
purified; its vitality is lowered; the functions of life are impaired; 
and the animals fall into such a state as to become an easy prey 
to any malady to whose exciting cause they may be exposed. 
Hence, it is obvious that attention to ventilation, and an abun- 
dant supply of pure fresh air, are essential to the health of ani- 
