ASCARIDiE 233 



by the horde of parasites in the ahmentary canal, is also a morbid factor. 

 ^Manifestations of the toxemia are often of a nervous character; there 

 is hyperrefiex irritability, and con^^.llsions are a not infrequent accom- 

 paniment. 



In general, it may be said of the ascarids that, while the}^ often in- 

 habit the intestines without perceptible indications of their invasion 

 other than their occasional expulsion with the feces, their presence con- 

 stitutes a condition calling for treatment. They should be expelled by 

 the administration of a vermifuge, in most cases followed bj' a purgative, 

 and their bodies collected and burned. Not only should the treatment 

 be carried out for considerations pertaining to the health of the host, 

 but to prevent the spreading about of the worms with their eggs and 

 embrvos to infest other animals. 



Ascarids of the Horse 



One species of ascarid inhabits the intestine of the horse, ass, and mule. 



Ascaris equi (A. megalocephala, A. equorum). Ascaridse (p. 229). — 

 This is the largest species of the family. The bod}' is yellowish white, 

 about the thickness of a lead pencil, and somewhat rigid. The head 

 is distinct and bears three lips. The caudal extremit}- of the male is 

 bordered laterall}' by two small membranous wings, and ventralh' on 

 each side there are 80-100 papilla. The female is considerably longer 

 and thicker than the male. The vulva is situated toward the anterior 

 quarter of the bod}'. 



Length of female: 15-30 cm. (6-12 inches), or it may be somewhat 

 longer. 



Eggs globular, 90-100 microns in diameter. 



The species is found only in Equida?, and lives in the small intestine, 

 occasionally found in oth(>r organs by migration. 



Occurrence and Symptoms. — The large ascarid is verj' common in 

 the small intestine of the horse. Unless numerous, they do not, as a 

 rule, perceptibly affect the health of their host, often the only evidence 

 of their presence being the voiding of one or more of the wornis with 

 the feces. Young annuals do not bear the parasitism so well, and in 

 moderate to hea^y infestations are likely to manifest serious disturb- 

 ances of a local and systemic character. 



As a result of the irritation to the mucosa there is a chronic intestinal 

 catarrh, and this may be accompanied by a diarrhea which is persistent, 

 or alternating with a hard dr}- feces covered with slimy mucous material. 

 Colic is a not infrequent s\nnptom, and there may be intervals of more 

 or less tympany. The worms, when massed in large numbers, are 

 capable of bringing about an obstruction with all that follows such a 

 condition, possibly involving intussusception and even rupture. 



