338 MANUAL OF EQUINE MEDICINE. 



but the female may attain a length of sixteen to eighteen 

 inches. 



This worm has a smooth body with transverse rings, and 

 may occur in any part of the intestinal canal, although 

 it is especially found in the ilium and small intestine. 



With regard to the question how horses become affected, 

 Dr. Cobbold writes : ' It is not likely that any intermediate 

 host is necessary for the growth of the larv?e, prior to their 

 access to the definite host. I have reared the larvae in 

 impure water and in moist horse-dung up to the size of ^^ 

 of an inch. They were then furnished with a completely 

 formed digestive apparatus.' Davaine kept the intra- 

 chorional embryos alive in water for five or six years. 



It is noteworthy that the eggs of lumbricoids effectually 

 resist dryness, and it is possible that horses become infected 

 with the ascarisby drinking out of ponds containing sewage 

 matter. 



The equine ascaris may prove fatal by setting up enteritis, 

 or by overcrowding it may cause rupture. 



Treatment. — Allow nourishing diet, and give internally 

 a brisk cathartic, e.g., aloes, with 5i. of antim. pot tart, 

 and follow with vegetable tonics, sulphate of iron, and doses 

 of santonine. 



Preventive Pleasures. — See that the water-supply is good, 

 pour boiling water on all worms passed, and attend to the 

 drainage. 



2. STRONaYLUS ARM ATUS.— This worm has long been 

 known to naturalists, and was formerly described as two 

 varieties, major and minor, which are now proved to be the 

 same worm in different stages of growth. 



Description.— The body of the worm is rigid, the head 

 lobular, flattened, truncated, and armed with numerous 

 uj^right denticles, like a circular saw. 



The i^osterior ray of the hood of the male is three cleft. 



