390 The Diseases of Animals 
In this, as in all other parasitic diseases, preventive 
treatment is the better and more economical. Sheep 
and lambs should be kept from infested pastures, and 
(in localities where the disease prevails) away from 
low. wet lands and stagnant water. As lambs acquire 
the parasite from the pasture or the drinking place, 
they do not contract the disease if they are kept housed. 
LUNG- WORM 
Lambs, pigs and calves are the animals most fre- 
quently attacked by this parasite (Stronylus filaria), 
although adults may be affected. It is seldom found in 
other species of animals. There are several kinds 
of worms that may attack the lungs, but the one men- 
tioned is most frequent, and does the most damage. 
It is closely related to the stomach-worm of the sheep. 
The young animals usually contract the disease from 
infested pastures, drinking places, troughs or pools of 
stagnant water. 
The animals fall away in flesh and present an un- 
thrifty appearance. They are subject to violent fits of 
coughing and strangling, often raising frothy mucus, 
which contains the small white thread-like worms, from 
one-half inch to one inch in length. The coughing 
increases and the debility becomes more marked until 
the animal dies. Usually there is difficult breathing, 
which is most marked when the animal is coughing, or 
directly afterwards. 
If the animal is fat and in good eondition, it is 
often the most economical plan to sell it to the butcher, 
