Cyathostomosis

Also known as:

Cyathostominosis

Description

Cyathostomins are also known as small strongyles, and are one of the most important gastro-intestinal parasites of the horse. Over 40 species and several genera have been identified. The small, thread-like worms inhabit the caecum and the large colon with their developmental stages confined to the mucosa of the large intestine. Unlike the large strongyles, they do not undergo any extra-intestinal migration during development. Larvae ingested may develop to the L4 stage without interruption, however some larvae may become arrested at the EL3 stage. It is the mass, synchronous emergence of these hypobiotic larvae that leads to the clinical disease of larval cyathostomosis.

Signalment

All horses may be affected but most are less than five years old. Disease commonly occurs in late winter or early spring.

Diagnosis

Clinical Signs

.

Prevention

.

References

• Blood, D.C. and Studdert, V. P. (1999) Saunders Comprehensive Veterinary Dictionary (2nd Edition) Elsevier Science

• Mair, T., Love, S., Schumacher, J. and Watson, E. (1998) Equine Medicine, Surgery and Reproduction WB Saunders Company Ltd

• Knottenbelt, D.C. A Handbook of Equine Medicine for Final Year Students University of Liverpool

• Pearce, O. (1994) Treatment of Equine Tetanus In Practice November 1994 pp 322-325.

• Merck & Co (2008) The Merck Veterinary Manual (Eighth Edition) Merial

Gross

• Encysted larvae appear as pinhead grey to red mucosal nodules.
• Mass emergence results in:
  • Mucosal erosions.
• Ulcers.
• Fibrinous exudates.
• Haemorrhage.

Histopathology

• Larvae in deep mucosa/sumucosa surrounded by fibrous capsule and mixed inflammatory cells.
• Intense eosinophil, neutrophil and macrophage infiltration when larvae emerge
  • May also be oedema and, if severe, mucosal ulceration.