PARASITES AXD PARASITIC DISEASES OF HORSES 27 



for each 250 pounds of weight, immediately preceded or followed by 1 

 quart of raw linseed oil or by an aloes ball. Cases of excessive purga- 

 tion have been reported in some instances following the use of raw 

 linseed oil. It is possible that this undesirable action is due to im- 

 purities in the product; consequently a good grade of oil should be 

 used. A mixture, said to be without the undesirable effects of raw 

 linseed oil, has been recommended as follows: For weanlings, castor 

 oil, 4 to 6 ounces, and mineral oil, 1 pint; for yearlings and 2-year-olds, 

 castor oil, 6 to 8 ounces, and mineral oil, 1 pint; for 3-year-olds and 

 older, castor oil, 8 to 10 ounces, and mineral oil, l l / 2 pints. 



Carbon tetrachloride also is of value for the removal of large 

 strongyles and is safer than oil of chenopodium for treating pregnant 

 mares. The close is 6 to 12 fluid drams (25 to 50 cubic centimeters) 

 for a 1,000-pound animal. Normal butylidene chloride is also effec- 

 tive. It is administered after a preliminary fast at a dose rate of 

 3 fluid ounces (90 cubic centimeters) for a 1,000-pound animal, and 

 followed in 5 hours by 1 quart of raw linseed oil. A closely related 

 chemical, normal butyl chloride, 

 is equally effective and is less 

 expensive but has the disad- 

 vantage of being metabolized 

 into a very unpleasant smelling 

 substance. This drug is used Figure m _ Sma il strongyles of the horse, 

 at a dose rate of approximately 



3 fluid ounces (90 cubic centimeters) for a 1,000-pound animal and 

 is administered in from 8 to 10 times its volume of raw linseed oil. 



Prevention. — Preventive measures designed to control strongyles 

 consist (1) in rotation of pastures, so far as possible, avoiding low and 

 wet pastures, and (2) sanitation of stables to prevent larvae from 

 developing to the infective stage and from contaminating the feed and 

 water. This is accomplished by daily removal of manure from stables, 

 supplying the feed in boxes and racks well raised above the floor, and 

 supplying clean water. The disposal of stable manure is an important 

 preventive measure, as is shown elsewhere in this circular. Little can 

 be accomplished in the way of pasture sanitation except on farms 

 where thoroughbred or other valuable horses are raised. On these 

 farms the removal of manure deposits from pastures may be practiced, 

 as this procedure will remove almost all the parasite material before 

 it can develop and spread. Such a procedure is necessarily trouble- 

 some and expensive and can be undertaken only by breeders to whom 

 the question of expense is of secondary importance. The average 

 breeder will have to resort to simpler and less radical measures, such 

 as avoiding the overstocking of pastures, frequent rotation of pastures, 

 and special attention to foals. ^Tiere overstocking and the use of 

 wet pastures are unavoidable, and rotation is impossible, reliance must 

 be placed on treatment as often as necessary for control. 



Horse breeders, and even the general farmer, should pay consider- 

 able attention to the sanitation of paddocks in which the newly born 

 foals are kept. The foals should be kept there for several weeks before 

 they are put on pasture. Removal of manure from the paddocks, at 

 least once a week, will cut down the supply of eggs and larvae to which 



