DISEASES WHICH ARE INDUCED BY PARTICULAR PARASITES 173 



exist in the small intestine, hut there is no record of its having been found 

 among horses in this country. All these tape-worms are peculiar in being 

 unarmed, that is, are not provided with a double row of hooks, which 



277. Tsenia perfoliata, 

 (V)iluilic Extremity (enlarged 

 7 diameters) 



Fig. 278. Tffinia plicata, 

 Cephalic Extremity (en- 

 larged 7 diameters) 



Tig. 279. Tsenia mamillana, 

 Cephalic Extremity (enlarged 

 15 diameters) 



are common in other varieties. Nothing is known of the hydatid stage, 

 which forms the intermediate condition between the tape-worm embryo 

 and the mature parasite. 



There are no indications whatever of the existence of the worms 

 during the life of the horse which they infest, and consequently no treat- 

 ment has ever been attempted. A remark- 

 able case is recorded of the existence of 

 nearly all the parasites which have been 

 described in one horse which was examined 

 by Veterinary Surgeon Krause. There 

 were found 519 Ascaris megalocej)hala, 

 191 Oxyurus curvula, 214 Strongylus 

 armatus, many thousands of Strongylus 

 tetracanthus, 69 TcBnia perfoliata, 287 

 Filaria papillosa, and 6 Cysticercus fas- 

 ciolarix. 



To complete the history of the parasites 

 which infest the digestive organs of the 

 horse it is necessary to allude to some 

 which 'are found occasionally in the liver. 

 The fluke (Distoma hepaticum) (fig. 280) 

 sometimes effects an entrance into the liver 

 ducts of horses, especially colts, which 

 are feeding on wet pastures where the 



embryos and larval forms of the parasite are abundant. Sheep, as is 

 well known, are destroyed in thousands in some localities by the invasion 

 of this parasite, which causes the disease known as rot. A few cases are 

 recorded of foals and colts having suffered from the accidental invasion 

 of the fluke, but the disease among horses must be looked upon as 



Fig. 280. Liver Fluke (Dintoma /le/mticum, 

 Linn.) 



A, Showing Anatomical details. B, Natural 

 size, c, Ciliated Embryo, or Young Distome. 



