ASCARIDiE 235 



Following the period of fasting, give two to four ounces of oil of tur- 

 pentine and one dram of oleoresin of aspidium, in a pint of linseed oil. 

 If necessary, follow twelve hours later with an additional pint or two of 

 linseed oil. 



Tartar emetic in two to three dram doses, repeated once at an interval 

 of twelve hours, is also an effectual expellant. This is best administered 

 with linseed meal which may be stirred into a small bran mash. 



These doses are for aged horses of average size, and are to be modified 

 according to age and somewhat as to weight. 



The vermifuge is in most cases to be followed twelve to twenty-four 

 hours later by a purge, preferably oleaginous, but this should not be 

 given if there is diarrhea, and may not be necessary if the animals are 

 upon grass. 



Sulphate of iron and arsenic are remedies which have also been recom- 

 mended. If arsenic is used, it should be given in the form of powdered 

 arsenous acid in increasing doses for about two weeks. 



Family II. Oxyuridse. Nematoda (p. 217). — This family is consid- 

 ered by many authors as belonging with the Ascaridse. Conspicuous 

 characteristics of the group are the curved anterior portion of the body 

 and the elongated and attenuated caudal extremity of the female. The 

 males usually have but one spicule, and this may be reduced and im- 

 perfectly developed. The vulva of the female is anterior. 



Oxyuris equi (O. curvula, O. mastigodes). Oxyuridse (p. 235). — 

 The body is generally white, somewhat thickened, and curved. The 

 mouth is provided with three lips. The male is much smaller than the 

 female, and has an obtuse caudal extremity which bears several papillae, 

 the largest of which sustains a caudal bursa. There is but one spicule 

 and this is straight and slender. In the female the anterior portion of 

 the body is thickened and curved, while the posterior portion is at- 

 tenuated to a point. The vulva is about 8-10 mm. (3/8 of 'an inch) from 

 the mouth. The body may have its posterior attenuated portion of 

 variable length (Fig. 122) ; in some individuals this is very much pro- 

 longed and filamentous. This difference has led some authors to 

 describe two species of Oxyuris of the horse — 0. curvula and 0. masti- 

 godes, the latter including those with the extended caudal extremity. 

 Railhet has demonstrated that forms exist possessing all intermediate 

 gradations between those with very short and those with very long tail 

 extremities, and that there is not, therefore, a difference of true specific 

 character. 



Length of female, 4-15 cm. (1 ,5/8-6 inches) ; male, about 1 cm. (3/8 of 

 an inch). 



Eggs oval and operculated; 85-95 microns long, 40-45 microns wide. 



The species inhabits all of the large intestine of .the horse, ass, and 

 mule. 



