PARASITES OF THE ALIMENTARY TRACT 67 
country. Colts and young horses are more frequently 
affected, but it is not at all uncommon to find the worms 
present in large numbers, often causing grave symptoms, 
in aged horses. Colts running at grass at first show 
gradual emaciation, pitched coat, and general signs of 
unthriftiness. As the disease progresses, weakness sets 
in, and the colts acquire a stiff gait, particularly behind, 
and often the joints may be heard to crack, somewhat 
resembling the sound heard in some rheumatic affec- 
tions. Ascites is not uncommon, but more frequently 
one sees cedema of the lips, with swelling of the legs 
from the hoof upwards. These symptoms arise from 
circulatory changes. At intervals attacks of colic occur, 
usually accompanied by diarrhcea and the passage of 
large numbers of worms. Death may occur during one 
of these attacks, but more often the colt gets on the 
ground, and shows inability or unwillingness to rise. 
In this case death soon supervenes. 
The attacks of colic are due to cutting off of the 
blood-supply from portions of the bowel, owing to ob- 
struction or embolism of small vessels. 
During the attack the animal usually lies, with the 
head extended on the ground. The pain is continuous, 
and may pass off as suddenly as it has come. The colt 
then stands up, but may appear very dull and stupid 
for some while after. 
In older animals Sclevostomum tetracanthum appears 
to be more commonly the cause of serious trouble than 
Sclerostomum armatum. 
The animal shows signs of gradual emaciation, usually 
with increased appetite, but occasionally the appetite is 
diminished. The coat stares and the mucous mem- 
branes are anemic. Ascites is comparatively rare in 
old horses. We have observed intussusception of the 
bowel as a result of their presence, though a number of 
Sclerostomum armatum were present at the same time. 
