Spirocerca		Contents		Rev: 10/25/2025
Esophageal Worms		Classification		Biology and Ecology
		Morphology and Anatomy		Life Cycle
Return to Spirocerca Menu				Ecosystem Functions and Services
		Distribution		Management
Return to Thelaziidae Menu		Feeding		References
		Go to Nemaplex Main Menu		Go to Dictionary of Terminology

Classification:

Chromadorea
Chromadoria

           Rhabditida 

Spirurina

              Thelazioidea

      Thelaziidae

                      

            Spirocerca

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Morphology and Anatomy:

• Adults are pinkish and coiled in large granulomatous nodules (up to golf ball size) in the wall of the esophagus or stomach
• Adults have a hexagonal mouth without definite lips but are surrounded by six masses of dense parenchyma (the pulps of the cephalic papillae).

Males:

• Length 30-54 mm, width 760 um
• Spicules unequal length (left spicule 2,4-2.8 mm long,  475-750 um long)
• Tail spiral

Females:

•  Length 54-80 mm, width 1.15 mm
• Tail dorsally curved, 400-450 um long.
• Vulva anteriorly  located, 2-4 mm from the anterior end.
•  Eggs narrow, ellipsoidal, and cylindrical with a smooth, clear shell; 30-38 x 11-15 um, containing a coiled L1.

Ref: Marchiondo and Cruthers, 2020

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Distribution:

Spirocerca lupi is a parasite of the esophagus in dogs and other canids of tropical and subtropical areas.

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Feeding:

Food Sources and Feeding strategies for the genus Spirocerca

Esophageal parasite of canids

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Biology and Ecology:

Infection causes nodular masses and granulomas of the esophagus in dogs with possible neoplastic transformation to osteosarcomas or fibrosarcomas. Adult nematodes are coiled in large granulomatous nodules (up to golf ball size) in the wall of the esophagus or stomach of the host.

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Life Cycle:

Dung beetles are intermediate hosts.

• Eggs shed in the feces or vomit of a definitive host contain L1 larvae and are immediately infective to coprophagous beetles that serve as natural intermediate hosts.
• Larvae hatch in the midgut of the intermediate hosts and develop and encyst as the L3.
• The domestic chicken, wild birds, and lizards serve as paratenic hosts with the L3 encysting in the viscera.
• The L3 are liberated from the intermediate or paratenic hosts after ingestion by a definitive host.
• The L3 penetrate the stomach wall of the definitve host and migrate to the thoracic aorta. They cross to the adjacent esophagus after 3 months and develop in about 3 months to adults within a granulomatous nodule
• The prepatent period is 5.5-6 months

Ref: Marchiondo and Cruthers, 2020

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Ecosystem Functions and Services:

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Management:

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References:

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Copyright © 1999 by Howard Ferris.
Revised: October 25, 2025.