440 VETEEINAEY HYGIENE 



and Pseudalms, the hair lung worm, are found in the sub- 

 stance of the lung. Husk is produced either by S. micrurus 

 or ,S'. filaria, and it is the disease caused by these that is 

 here being dealt with from a hygienic standpoint, though 

 it must also be observed that S. rvfescens is capable when 

 in large numbers of causing very heavy loss. 



In parasitic bronchitis, both worms, eggs, and embryos 

 are expelled in enormous numbers from both the mouth 

 and nostrils, by the continual cough caused by their irrita- 

 tion. A fully grown female worm is capable of discharging 

 several millions of embryos, and though this vast number 

 finds its way to the soil, it is a fortunate circumstance that 

 an intermediate host is required before they can again 

 infect cattle and sheep. There is very good reason for 

 believing that the larval stage is passed in the earthworm, 

 and after undergoing certain changes is ejected from its 

 body, and finds its way on to the surface of the soil with 

 the worm castings. If this proves to be the invariable life- 

 history, the infection of flocks and herds can be readily 

 understood. 



The conditions which favour infection are overcrowding 

 of animals on the land, a debilitated state of the system 

 through insufficient food, low-lying and swampy pastures, 

 infected and stagnant water-supply. In connection with 

 this, it may be observed the opinion is pretty generally 

 held that infected food is a more frequent source of disease 

 than infected water-supply. 



The preventive measures are much the same as have 

 already been discussed under Fluke disease. The animals 

 must be liberally fed and receive salt ; the soil drained, 

 stagnant water railed or hurdled off, marshy or low-lying 

 land avoided, and a top dressing of lime and salt tried. 

 The driest portion of the farm should be selected, but it 

 hardly seems wise to turn the affected animals on to uncon- 

 taminated pastures, considering the amount of parasitic 

 material they are constantly ejecting. It would be far better 

 to trough feed them and hurdle them off, changing ground 

 frequently, and top dressing all the places occupied by 



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