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 likewise 

 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 present. 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 irri- 

 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 prescribed 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 



