PARASITES AND PARASITIC DISEASES OF HORSES 11 
This disease has been studied in Europe, Africa, and elsewhere, 
where it has been noted that its seasonal occurrence corresponds to 
the prevalence of flies. It is unlikely that the worm larve invade 
the unbroken skin, but it appears to be well established that when a 
horse’s skin is broken by some injury and when flies which carry 
the worm larve feed on the sores, the larvae escape from the mouth 
parts of the fly and live for a time in the wounds. These larvee irri- 
tate the sore, so that instead of healing as a simple sore it may 
become a more or less chronic thing which does not heal until after 
the occurrence of frost in the fall. 
Although conditions known as “summer sores” in horses are 
known to occur in the United States, the disease has not been exten- 
sively studied here and the relation of stomach-worm larve to sum- 
mer sores still needs further investigation in this country. Recently 
the occurrence of the larval worms from summer sores in horses in 
the United States has been definitely reported. 
Treatment for summer sores.—An astringent powder which is said 
to prevent the extension of the trouble and to aid in healing consists 
of the following: Plaster of Paris, 100 parts; alum, 20 parts; naph- 
thalene, 10 parts; and quinine, 10 parts. 
Good results are reported from the use of a caustic paste composed 
of arsenious oxide, 1 part, and flour, 5 parts. Washing the sores with 
ether or chloroform and then painting them with collodion has also 
been recommended. Some veterinarians prefer the use of a 5 to 10 
per cent solution of formalin, applied by means of a cotton pad 
which is left on the sores for two to three hours every day. 
Prevention.—Skin injuries should be protected from flies by the 
use of pine-tar oil or other means to prevent their conversion into 
summer sores. 
THE SMALL STOMACH WORM 
This parasite, 77ichostrongylus awxei, occurs in the lining of the 
stomach, and is likely to be overlooked as the worms are very slender 
and only about one-fifth of an inch or less in length. 
Life history.—The life history of this parasite has not been defi- 
nitely ascertained. In a general way its life history is similar to 
that of blood strongyles, described elsewhere in this circular, with 
respect to the development of the eggs and larve on pastures. It is 
also fairly certain that infestation is direct, and results from the 
swallowing, by horses, of the infective larve with food or water. 
However, these worms burrow only into the stomach wall and are 
not known to wander extensively, as young worms, throughout. the 
body of the horse. 
Symptoms and lesions——These parasites injure the stomach wall. 
Sometimes the stomach lining shows areas superficially like a ring- 
worm or a mass of small tumors. (Fig. 5.) In addition to these 
injuries, the parasites contribute to general gross parasitism in 
horses which is characterized by weakness, paleness of the mucous 
surfaces, wasting, and digestive disturbances. 
Treatment.—Treatment for the removal of this parasite is similar 
to that recommended for the large stomach worms. However, this 
treatment has not had critical test to determine its exact. efficacy 
against the small stomach worm. 
