16 CIRCULAR 148, U. S. DEPARTMENT OF AGRICULTURE 
from 6 to 12 fluid drams (25 to 50 cubic centimeters) for a 1,000- 
pound animal. This drug does not need to be: accompanied with a 
purgative, but it is usually advisable to give purgatives, in this case 
salts, with carbon tetrachloride for removing worms. 
Prevention.—Prevention of ascarid infestation requires special 
care of foals and young horses. The time to begin is before the foal 
is born. The foaling barn should be of sanitary construction and 
should be cleaned and washed with hot water and lye before the 
pregnant mare is placed in it. The mare and foal should be kept 
in a clean paddock, adjoining the barn. It is best to use a paddock 
from which other horses have been absent for at least a year, and 
preferably longer. The stable and paddock in which the mare and 
foal are kept should 
be cleaned often, 
daily if possible, ht- 
ter and manure being 
removed. 
These precautions 
are designed to pre- 
vent the foals from 
becoming heavily in- 
fested with ascarids 
at an early age, and 
before they have de- 
veloped the necessary 
reserve vitality to 
cope successfully 
with a heavy worm 
infestation. When 
the foal is moved to 
a pasture it is essen- 
tial to select one 
which is clean and 
that has not been 
used by horses for a 
vear or _ longer. 
Horses may be 
moved to cow and 
Figure 9.—Type of insanitary box stall. Note accumu- sheep oS TTEES and 
™ "ation of litter’ and manure vice versa, because 
parasites of rumi- 
nants are not transmissible to horses, and equine parasites are not 
transmissible to cattle and sheep, as a rule. Proper disposal of 
manure, and sanitary measures recommended in connection with the 
control of blood strongyles will also help to prevent infestation with 
ascarids. 
While infestations with ascarids can be acquired on pastures, and 
often are so acquired, it is important to remember that ill-kept 
stables, in which manure is allowed to accumulate (fig. 9), are also 
the sources of heavy infestations with intestinal roundworms, pin- 
worms, and other threadworms. Under pasture conditions many 
eggs and larve succumb to drought and to other unfavorable in- 
fluences which prevail in the open. In manure-laden stalls parasite 
