Dirofilaria immitis		Contents		Rev 09/20/2022
Dog Heartworm; Heartworm		Classification		Biology and Ecology
		Morphology and Anatomy		Life Cycle
Return to Dirofilaria Menu				Ecosystem Functions and Services
		Distribution		Management
Return to Onchocercidae Menu		Feeding		References
		Go to Nemaplex Main Menu		Go to Dictionary of Terminology

Classification:

Chromadorea
Chromadoria

 Rhabditida 

                  Spirurina

                                  Filarioidea

                           Filariidae

Onchocercidae

 

           

Dirofilaria immitis Leidy, 1856

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Morphology and Anatomy:

Males:	Female:
Reported median body size for this species (Length mm; width micrometers; weight micrograms) - Click:

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Distribution:

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Economic Importance:

Veterinary fees, diagnostic tests, medicines for household pets.

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Feeding:

Dirofilaria immitis is a parasite that feeds exclusively on the blood of the host.

The nematode usually occupies the right chamber of the heart and the pulmonary arteries of dogs, foxes, wolves, coyotes, and cats.

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Hosts:

Dogs, foxes, wolves, coyotes, and cats.

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Biology and Ecology:

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Life Cycle:

(Lifecycle diagram from American Heartworm Society)

Dirofilaria immitis has an indirect life cycle. 

• The adult parasite sexually reproduces in its vertebrate host, and the offspring are transferred to the intermediate host, which is usually a mosquito or a flea. 
• The larva develops inside the intermediate host and molts twice.
• When the intermediate host feeds, the larvae enter the new vertebrate host through the wound. 
• The parasite remains dormant in the vertebrate hosts muscle tissue for 85 to 120 days. After this time period, the parasites enter the host's blood stream, where they are carried to the heart.
• Completion of the life cycle in the heart requires 7 to 9 months.

Ecophysiological Parameters:

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Ecosystem Functions and Services:

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Management:

Monthly medication with Avermectin is a preventative.

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References:

Olson, Wilford O. 1962. Animal Parasites-Their Biology and Life Cycles. Burgess Publishing Company, Minneapolis pp.315

Noble and Noble. 1964. Parasitology-The Biology of Animal Parasites. Lea and Febiger Co., Philadelphia pp.310

Material from Heather Hathaway, 1995.

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Copyright © 1999 by Howard Ferris.
Revised: September 20, 2022.