92 DISEASES OF THE HORSE. 
trap, consisting of an exposed manure platform raised on posts which 
are set in a concrete basin extending under the platform and filled 
with three or four inches of water, has been devised. As maggots 
work down they come to the platform and escape through the spaces 
between the boards, left open for the purpose, to the water in the con- 
crete basin, where they are drowned. In this way the exposed 
manure pile serves to attract flies with a deceptive proffer of a breed- 
ing place. 
Apparently it is the young forms of these stomach worms which 
develop at times-on the skin, causing a cutaneous habronemiasis 
known as summer sores. This is discussed under diseases of the skin. 
Srroncrtes (Strongylus spp. and Cylicostomum spp.)—These 
. worms (PI. V, figs. 2 and 3) live in the large intestines of the horse 
iw 
as adult worms and are often present in enormous numbers. Many 
of them are very small, and the largest are less than two inches long. 
The adult worms do considerable damage, but the immature or larval 
worms do even more. 
The larva of Strongylus vulgaris enters the blood vessels of the 
intestinal wall and finally attaches in the great mesenteric artery, 
where it causes aneurisms; here it transforms to an adult without 
sexual organs, which passes to the walls of the cecum .and encysts, 
giving rise to small cysts or abscesses; these cysts finally discharge 
to the interior of the cecum, setting the worms, now mature, at lib- 
erty in the lumen of the intestines. 
The larvee of Strongylus equinus are found principally in the liver, 
lungs, and pancreas. 
The larve of Strongylus edentatus may be met with almost any- 
where, especially under the serous membranes, the pleura and peri- 
toneum. 
The embryos and larve of species of Cylicostomum are found in 
the mucosa of the large intestine. 
Aneurisms impede the circulation of the blood, and may give rise 
to intermittent lameness. The aneurism may rupture, since it con-. 
stitutes a weak place in the wall of the blood vessel, and the horse 
die of the resulting hemorrhage. Particles of blood clots in the 
anéurisms may break off and plug a blood vessel at the point where 
they lodge, thereby causing the death of the part from which the 
blood is shut off and occasioning a type of colic which often termi- 
nates fatally. The larve of Cylicostomum form cysts in the walls 
of the large intestine, and when these open they give rise to small 
sores; when they are numerous they cause a thickening and harden- 
ing wile impair the proper functioning of the intestine. Abscesses _ 
sometimes perforate, causing death. The adult worm attacks the 
intestinal wall, causing bleeding which results in anemia. The 
