Craterostomum spp, Oesophagodontus spp, Gyalocephalus spp, and Cyathostomum spp: These are four of the approximately eight genera generally referred to as small strongyles.

General Description: These worms range from 4 to 26 mm. in length and are similar in life cycle.

Life Cycle: These parasites undergo a typical direct nematode life cycle outside the host. There is a period of larval development within the mucosa.

Location: Large intestine and cecum.

Geographical Distribution: Widespread.

Significance: Small strongyles may cause considerable economic loss and severe disease.

Effect on Host: Small strongyles are usually seen in mixed infections. Damage is mainly attributable to the activities of the adult worms in the large intestine. However, the larvae within the gut walls may also suck blood. These worms, like the large strongyles, are plug feeders, ingesting plugs of intestinal mucosa and blood vessels. The mouth, or "buccal" cavities, of small strongyles are smaller than those of Strongylus species and make shallower bites, with less damage to underlying blood vessels. Diarrhoea, anorexia, colic, and weight loss are symptoms of heavy infections.

Diagnostic Information: Strongyle eggs passed by foals of 6 months or less may be assumed to be those of the small strongyles, as the prepatent periods of Strongylus species are longer than this. Species identification is impossible solely or the basis of egg morphology. Larval differentiation through specialised procedures such as faecal cultures is possible.

Control: Regular treatments with anthelmintics are necessary. In particular, since foals are very susceptible, brood mares should be treated and moved to clean pastures. Overcrowding must be avoided. Removal of faeces and ploughing to break dense ground cover will aid in control of strongyles. Resistance to benzimidazole, morantel and pyrantel anthelmintics has been reported for this group of parasites.

Cyathostomun		Small strongyles in nodes in the mucosa