20 CIRCULAR 148, U. S. DEPARTMENT OF AGRICULTURE 



(2.2 pounds) of body weight or 10 cubic centimeters (2.5 fluid drams) 

 for a 220-pound animal. In order to remove the bulk of ingesta in 

 the small intestine and render the parasites more accessible to treat- 

 ment, it is advisable to administer a purgative 24 hours before treat- 

 ment, and to withhold feed until after the carbon tetrachloride has 

 been given. A suitable purgative for foals consists of castor oil, 4 to 

 6 ounces, and neutral oil (mineral oil) 1 pint. This treatment has 

 not had critical test to determine its precise value. 



Prevention. — Prevention consists in special precautions with ref- 

 erence to stable sanitation, special care of foals, especially as regards 

 clean bedding which should be changed daily, if possible. Other 



Figure 12. — Portion of the tip of the cecum of a horse, showing blood strongyles 

 attached to the inner lining of the gut. The large worms are S. equinus; the small 

 ones are S. vulgaris. Natural size. 



preventive measures are similar to those recommended in connection 

 with the discussion of ascarids and blood strongyles. 



THE LARGE STRONGYLES OR PALISADE WORMS 



The large strongyles are roundworms commonly known as blood 

 worms, red worms, sclerostomes, or palisade worms. They are red in 

 color and are commonly found firmly attached to the wall of the gut 

 (fig. 12) by means of a rather formidable mouth cup. Three species 

 of blood strongyles are of common occurrence in the colon and cecum 

 of the horses, as follows: 



The large strongyle, St^ongylus equinus (fig. 13, C), is from about 

 1% to nearly 2 inches long by about one twenty-fifth to one-twelfth 

 of an inch wide; the mouth cup contains three teeth. The toothless 

 strongyle, Slrongylus edentatus (fig. 13, A), contains no teeth in its 

 mouth cup ; otherwise it is similar in appearance to the large strongyle, 



