98 DISEASES OF SHEEl'. 



out resistance. The winking membrane of the ej'es, as well 

 as the skin under the wool, is pale, symptoms of catarrh 

 or cold in the head appear, and the patients cough and 

 groan very frequently. 



After a time the cough becomes more frequent, labored, 

 sharp and moaning or dull and moist ; the animal sneezes 

 and makes efforts to vomit from time to time. The respira- 

 tion becomes more and more laborious, and causes a visible 

 motion of the flanks and nostrils. Notwithstanding the 

 good appetite which is generally present, the lamb con- 

 tinually loses flesh and becomes weaker, until finally it dies 

 of general debility and exhaustion or of suffocation. The 

 disease is generally very slow, and lasts not unfrequently 

 two or three months, or even longer, before death ensues. 



On dissecting the body the principal changes are found 

 in the lungs, which are generally flabby, pale or even white, 

 contain little blood, and show knots and callous elevations 

 at different points. In the windpipe and the bronchial tubes 

 are found much frothy mucus and an immense number of 

 worms, which are often in balls. They are about one or 

 two inches long, not much thicker than sewing thread 

 and of a yellowish-white color. They constitute the species 

 Strongyliia hroncliialk. 



Nothing positive is as yet known concerning the causes 

 of the disease. It probably originates from a common cold 

 in the head or from catarrh of the lungs, which causes the 

 formation of the worms in the lungs by its long duration 

 under the influence of other injurious circumstances. To 

 these belong colds of all kinds, the long-continued action 

 of rain or moisture, stormy weather, cold, damp air, etc., as 

 well as poor and sparing food, which causes the animal to 

 lose strength. 



The disease is very dangerous and destroys most sheep 

 which it attacks. It is only at first, as long as the animal 



