76 
Parasites of Cattle and Sheep. 
not be taken for granted that these strongyles are responsible for 
all cases included under these designations. It is sometimes 
possible to find the parasite in the faeces, which is, of course, 
proof positive, though the results do not always justify the 
trouble of searching. 
Prevention . — It is most important to bear in mind the fact 
that infested animals, whether showing signs of the disease 
or not, are passing the eggs of the worms. If at grass, these 
are scattered over the pasture, rendering it dangerous to 
other susceptible animals. This method of distribution of 
parasite ova is one of the main factors in bringing about that 
condition of pasture known as soiled, foul, over-stocked, and 
cattle-sick. Animals known to be, or suspected of being, 
infested with worms should be kept indoors, and their 
droppings ploughed deep into the land, or burnt. Young 
cattle, especially, should not be grazed on pastures known to 
be infested. Horses, adult sheep, and adult cattle run fewer 
risks on such pastures. There is no reason for thinking that 
the eggs or embryos of the worms live apart from animals 
for indefinitely long periods, so that if it were practicable to 
keep susceptible animals from infested pastures for twelve 
or eighteen months, it is probable that the danger would be 
removed. The ploughing of infested grass land — we grant not 
often practicable — is likely to render such free. Though little 
is known of the life-history of the worm, many circumstances 
indicate the desirability of preventing access to dirty pools, 
and avoiding depasturing on land which has been flooded. 
Top-dressings of lime and salt are advocated, and such may 
be, in some degree, beneficial from this point of view, while 
recent experiments will appear to indicate on other grounds 
the desirability of the more frequent use of lime. Though 
such agents may not, even in large quantities, destroy all adult 
parasites, it is possible that they provide conditions detrimental 
to them. Cattle may harbour a few of these strongyles, while 
they show no symptoms, and it is important to remember that 
each female worm is capable of laying an immense number of 
eggs, and so possibly of maintaining the existence of the disease 
on a place, or of taking it to fresh situations. Adult animals 
withstand attack better than the young. It is therefore a 
better practice to allow the younger to have the first bite 
than to follow adults in grazing. 
It must be confessed that this form of parasitic invasion is 
not readily amenable to curative treatment. While it cannot 
be denied that the administration of remedies in some cases 
materially assists in recovery, a certain, indeed, a large pro- 
portion of cases, in which the symptoms are marked, appear 
not to be favourably affected by any drugs administered. In the 
