6 



CIRCULAR 148, U 



DEPARTMENT OF AGRICULTURE 



The dwarf tapeworm of horses. Anoplocephala mamillana (fig. 2), 



is only from about one-fourth of an inch to 2 inches long- and from 

 one-sixth to one-fourth of an inch wide: the head of this worm is 

 very minute and is barely visible to the naked eye. This tapeworm 

 occurs in the small intestine and is occasionally found in the stomach. 

 A third species of tapeworm, intermediate in size between the 

 large tapeworm and the dwarf tapeworm, is known as the perfoliate 

 tapeworm, Anoplocephala perfoliate. It is usually from about 

 three-fifths of an inch to over 3 inches long. It occurs usually in 

 the cecum and lower portion of the small intestine. The parasites 

 often become localized in a small area surrounding the opening of the 



y 1 Mb- S+* 





Am 



^^^■■^■■^■■■■■■^^^ THBHWiMliiiiii i aiM—^^B 



Figure 1. — Almost a gallon of large tapeworms. Anoplocepbala magna, removed 

 postmortem from a horse. About one-half natural size. (Photograph by cour- 

 tesy of the Agricultural and Mechanical College of Texas.) 



small intestine into the cecum, the so-called ileocecal valve region, 

 where they produce irritative and inflammatory changes, as well as a 

 rapidly growing mass of tissue which progressively obstructs the 

 opening of the intestine. This species is fortunately much less com- 

 mon in American horses than the other two species of tapeworms. 



Symptoms and lesions. — In light infestations no symptoms are 

 present. Horses which are heavily infested with tapeworms may 

 suffer from intestinal catarrh, show digestive disturbances of vari- 

 ous sorts, and in cases of very severe infestations they may become 

 emaciated and anemic. The perfoliate tapeworm of the horse 

 often occurs in large numbers when present at all. and is said to 

 produce inflammation of the intestines: sometime- it ruptures the 

 wall of the cecum. The attachment ol tapeworms of this species 



