DISEASES OF SHEEP 593 



areas are small, limited to the point of parasitic involvement and re- 

 sembles the ordinary catarrhal form. With the exudate numerous 

 worms and eggs are thrown off in the act of coughing. The fact 

 that the worms are present in every stage of development and tu- 

 bercles show every condition from the hemorrhage to dry caseous 

 and calcareous infiltration indicates that multiplication may take 

 place in the lungs as well as from infection from without. 



The diagnosis can not be made until the disease has progressed 

 to the point of producing pneumonia and a post-mortem is made. 

 The prognosis will depend upon the extent of parasitic invasion. No 

 medicinal treatment can be given that will secure the expulsion of 

 the worm. 



As a preventive precaution, pastures where the disease has been 

 known to occur should be abandoned for at least a year. It is desir- 

 able that the sheep be pastured upon land that has been under con- 

 tinuous cultivation as that tends to destroy any parasites that may 

 be present. 



THE THREAD LUNG WORM (STRONGYLUS FILARA, RUD). 



This is the larger lung worm and is the one generally referred 

 to by most observers in reporting lung worm disease. It may be 

 seen on opening the trachea and bronchi and is identical with that 

 found in calves. Curtice regards this as of being of less frequent 

 occurrence than the hair worm and that it often occurs that the 

 lesions found due to the hair worm are erroneously ascribed to this 

 one. 



The complete life cycle of this worm is not fully determined. 

 The eggs, or rather the embryos, are expelled by the act of coughing 

 and distributed upon the pasture, the feed, water trough and what- 

 ever may be near. How much time is necessary to be spent outside 

 the body and whether they must pass any part of their existence in 

 some lower animal is not known. How the parasite finds its way 

 into the lungs, too, after being taken into the mouth with the food 

 or water is not clearly demonstrated. The worm develops quite 

 rapidly in the bronchi and is found to affect principally lambs and 

 young sheep, thus differing from the hair lung worm. The symp- 

 toms of lung worm are those due to the irritation of the bronchial 

 tubes. The bronchitis differs in no respect from a bronchitis asso- 

 ciated with a cold. There are accumulations of mucous, sometimes 

 of a bloody character, sometimes a cough and expulsion of this mu- 

 cous. In some cases the cough is the prominent symptom and in 

 that way gets the name of hoose. With it may be difficulty in 

 breathing. The general health is impaired. The appetite may re- 

 main good, but what is eaten does not seem to do much good. The 

 wool becomes dry and harsh, without yolk, slips easily, the skin is 

 thin and tender giving the name of paper skin. There is paleness 

 of the mucous membranes of the eyes and lips. The animals are 

 thin and become exhausted easily either from exercise or exposure. 

 The course extends over a period of three or four months. 



^ The disease is most noticeable in summer, fall and early winter, 

 begins to wane during the middle of winter and practically disap- 



