S2 Treatment of Grass Land for Elimination of Disease. 



The elimination of this disease from grass hind may with this 

 knowledge be attempted on precise lines directed to ])reaking 

 the life cycle of the parasite, which may under some circum- 

 stances be accomplished by not grazing sheep and other 

 susceptible animals on pastures on which surface water 

 accumulates or stagnant pools exist, or by the application of 

 salt to the surface with a view of establishing conditions 

 inimical to fresh-water snails. Our recent weather experiences 

 prove the futility of attempting the former during the past 

 season. Another instance in which a complete knowledge of 

 the life-history of a parasitic worm permits of the adoption of 

 precise measures for the prevention or elimination of disease 

 from grass land is the case of the affection familiarly known 

 as gid, sturdy, tiirnsick, &c. This disease, which affects 

 animals of various species, but, in particular, sheep and lambs, 

 is induced by the pressure of a bladder or " hydatid " in the 

 brain or spinal cord. Though usually met with in only a small 

 number of animals in a flock, our pastures may be so con- 

 taminated with the eggs of the tapeworm, of whose existence 

 this bladder represents one phase, that 25 per cent, or even a 

 larger proportion of the lambs grazing on it may succumb to 

 attack. The tapeworm, whose eggs are taken from the 

 contaminated pasture by sheep, is in its mature form an 

 inhabitant of the intestine of the dog by which its eggs are 

 deposited on pastures. The eggs ingested by sheep and other 

 stock pass to the brain and develop into the bladder, which 

 contains hundreds of heads, each of which on being eaten by 

 the dog may develop into a mature tapeworm. This form of 

 contamination may be averted by preventing dogs from eating 

 heads of affected animals unless they have been previously 

 boiled so as to kill the tapeworm heads within the bladder ; or 

 by Ijringing dogs, liable to go on to the grass land, within 

 an enclosed space, dosing them with medicine for the expulsion 

 of tapeworm, and destroying their excreta. 



It may be remarked that in regard to elimination of disease 

 due to tapeworms and long round worms (Ascarides), we enjoy 

 a special advantage in possessing a reliable means of causing 

 expulsion of the injurious parasites from infested animals. 

 Occasionally animals on our grass lands become somewhat 

 severely infested with tapeworm or ascarides and our pastures 

 much polhited by their ova. Severe losses among lambs and 

 young horses from these causes have come within our observa- 

 tion. The treatment of pasture with the view of eliminating 

 these forms of disease is best effected by placing the animals 

 harbouring the worms on to land al)out to be ploughed and to 

 administei- appropriate drugs for the expulsion of the worms 

 and their eggs, which probably perish after l)eing ploughed in. 



