Page 851 - The Veterinary Care of the Horse

surfaces such as the conjunctiva, open wounds and the male genitalia. These larvae may

produce sores but do not develop into adult worms.
VetBooks.ir Clinical signs

In the stomach, large numbers of worms can cause a mild gastritis, but this is rarely a

problem. However, when larvae crawl into other sites, they cause itchy, granulomatous
lesions to develop. These raised patches may be a pink or reddish-brown colour and contain

gritty white or yellow nodules. There may be local swelling and discharge from the sheath
and eye (Figures 18.15a and b). If the gritty nodules impinge upon the cornea, it may become
ulcerated. Infected open wounds often develop exuberant granulation tissue and do not heal

as expected (Figure 18.16). Since they occur in the summer months when the flies are around
in large numbers, they are often called summer sores.

Figures 18.15a and b a) typical lesion caused by Habronema at the medial canthus of the eye; b) lesions on the conjunctiva
and eyelid at the medial canthus