The prevalence, relative abundance and site distribution of nematodes of the subfamily Cyathostominae in horses killed in Britain.

The research investigated the occurrence and distribution of Cyathostominae, a subfamily of nematodes, in horses’ large intestine, in southwest England from 1972-1974. The study revealed different species of such nematodes present in varying abundance at various times of the year and in different regions of the large intestine.

Cyathostominae Species Prevalence and Abundance

• 21 species of Cyathostominae were found in the large intestine of 86 mature horses but their occurrence varied. Six species, namely Cylicostephanus longibursatus, C. goldi, C. calicatus, Cyathostomum catinatum, C. coronatum and Cylicocyclus nassatus, were found in above 80% of the horses studied.
• 12 of the remaining species were found in less than 30% of the horses.
• The five most abundant species – C. nassatus, Cyathostomum catinatum, Cylicostephanus longibursatus, C. minutus and C. goldi – made up above 90% of the total number of adult cyathostomes encountered.
• The most prevalent cyathostomes were generally those species with the highest prevalence.

Temporal Variation of Cyathostominae Population

• The study found adult cyathostome populations to surge to an average over 400,000/horse) in April-June and another smaller surge in November-December.
• Similar fluctuations occurred for the populations of 4th-stage larvae in the lumen.

Distribution of Cyathostominae in the Large Intestine

• The research saw that the three regions of the large intestine had different cyathostome species compositions.
• The dorsal colon was predominantly occupied by C. longibursatus and C. goldi, the ventral colon by Cylicocyclus nassatus and Cyathostomum catinatum, and the less inhabited caecum accommodated several equally abundant species.
• Each species manifested a characteristic site distribution, with 11 of them occurring primarily in the ventral colon, eight in the dorsal colon, and two in the caecum.

Cyathostominae Infection

• The research also explored the changes in the site distributions of C. catinatum and Cyclicocyclus nassatus and the cyathostome burdens in relation to the epidemiology of cyathostome infections.