PARASITES AND PARASITIC DISEASES OF HORSES 3 
possible. The common practice of spreading horse manure on pas- 
ture plots adds to the parasite burden of the pastures. Suitable 
treatment of manure before spreading, as described in this circular, 
will prevent this added contamination. 
MEDICINAL TREATMENT 
It is not always practicable on the average farm to apply the 
sanitary measures necessary for the prevention of parasitic infesta- 
tion in horses. Treatment is, therefore, an important consideration. 
Periodic treatment will not ‘only reduce infestation in parasitized 
horses and render the animals more serviceable but will lkewise 
reduce the output of eggs in the manure, with a resultant decrease 
in stable and pasture contamination. 
Prevention of parasites in horses by the application of sanitary 
measures is the business of the horse owner, but the diagnosis and 
treatment of parasitic diseases are functions of the veterinarian. 
Different parasites require different and more or less specific treat- 
ments. Before these treatments can be intelligently applied it is 
necessary to know which species of parasites are pr esent. The veteri- 
narian is qualified by training and experience to ascertain this. 
Drugs used in treatments for horse parasites should be adminis- 
tered, as a rule, in capsules or by stomach tube, the latter being the 
preferred method for certain drugs. If capsules containing an 1rT1- 
tant or volatile drug are broken in the mouth, some of the drug may 
be drawn into the “windpipe and cause serious consequences. All 
drugs used in the treatment of horse parasites are poisonous, being 
intended to poison the parasites, and great care must be used in 
selecting the dose in accordance with the weight and condition of the 
animal. Some drugs should not be used in : the presence of certain 
conditions and, if used under such unfavorable circumstances, may 
cause serious results. Because treatment involves diagnosis and an 
intimate knowledge of how a drug acts and when to use it or not 
to use it, it is advisable that all treatments for horse parasites be 
administered by a veterinarian. 
The treatments recommended in this circular are, for the most 
part, those which have been found by experimentation to be the 
most effective for the parasite or parasites involved. Many drugs, 
some of them long purported to be of value for the expulsion ‘of 
worms from the horse, have been found to be practically worthless 
for this purpose when critically tested. Among such preparations 
may be mentioned iron sulphate, arsenic, copper sulphate, and tartar 
emetic. These drugs are frequently pr escribed for adminstration in 
the feed, a method which is very unsatisfactory and ineffective even 
with drugs known to be effective when given in capsule or by stom- 
ach tube. For this reason it is essential to administer worm reme- 
dies in accordance with the methods recommended in this circular. 
Before the administration of worm remedies animals should be 
fasted for the length of time prescribed under the various treat- 
ments. The withholding of feed reduces the bulk of the contents 
of the digestive tract and permits the drug to reach the parasites 
more certainly and effectively. Water should be allowed during 
the period of preliminary fasting, but it is advisable to withhold 
both feed and water for four or five hours after dosing. To keep 
