CHAPTER IV. 



I N T E S T I N A L P A R A S I T 1: S 



Bots. Ascaris Megaloccpha^ or Large-headed Liind)ricoid Worm. Oxyuris 

 Curvida^ or Mazu I For;//. Strongylus Tetraeanthus, or Foiir-Spined 

 Strofigyle. Strongylus Arniatus, or Armed Strongylc. Eehinoeoecus 

 Veterinorum^ or Common Hydatid of the Hojse. 



Although one is generally disposed to hear and speak of worms with 

 anything but pleasurable feelings, we need hardly tell our readers that there 

 .are few creatures, whose development and growth are more wondrous or 

 more interesting, than that of the several intestinal parasites. It is not, 

 however, our purpose to enter deeply into the life histories of these creatures, 

 but to cast a glance over the modes of their living, and to describe in 

 as simple a manner as we are able, the methods to be adopted in order to 

 rid the horse of his self-invited guests. We shall treat of six different 

 varieties of internal parasites. The other kinds are so rarely met with, as 

 to require no description at our hands. 



The first of the parasites of the horse of which we have to speak is the 

 •common gad-fly, or oestrus equi, whose larval form is the bot. All our readers 

 have heard of the gad-flies, which prove so irritating to oxen by piercing 

 through their hides. The female gad-fly settles on its victim while out at 

 grass, late in the summer, not for the sake of deri\ing sustenance for herself, 

 but for that of providing a suitable habitat for her eggs. It is at this 

 time of the year that she deposits her eggs on the hairs of the coat, and this 

 she is enabled to do by means of a thick, sticky fluid. The fly generally 

 selects, as sites for depositing her eggs, those parts of the horse which the 

 .animal can reach easily with the tongue, namely the shoulders, the lower 

 part of the neck, and the inner parts of the forelegs, especially around the 

 knees. The horse frequently licks the portion of coat on which the eggs 

 have been deposited. They gradually become hatched in about three weeks 

 from the time of their deposition by the gad-fly, and the larval form or 

 maggot makes its escape out of its enclosing egg-shell. The maggots are 

 then carried to the horse's mouth, and ultimately to his stomach along with 

 his food and drink. Necessarily, as Professor Williams points out, many larvai 

 perish during this passive mode of immigration ; some being dropped from 

 the mouth, and others being crushed in the food during mastication ; but 



