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First reported heartworm in a coyote from Prince Edward Island

Two wild coyotes standing on a grassy slope in Grasslands National Park, Canada
Research · Disease, parasites & microbiology

A coyote (Canis latrans) from Prince Edward Island has provided the first reported case of the heartworm Dirofilaria immitis in the species on the island. The parasite was found as an adult male nematode in the animal’s right ventricle and confirmed by both morphology and DNA analysis, according to a case report published on 1 June 2026 in The Canadian Veterinary Journal.

The coyote had been hunted near Summerville, Prince Edward Island, in January 2021. Its carcass was frozen at −20 °C and later examined in June 2024. During dissection of the heart, researchers recovered an adult nematode from the right ventricle.

The worm’s size and anatomical features were consistent with D. immitis. To verify the identification, the researchers extracted DNA and used PCR to amplify a gene encoding a surface antigen specific to the parasite. Sequencing showed 99% identity with published D. immitis sequences in GenBank.

Dirofilaria immitis is transmitted by mosquitoes. Canids are its principal definitive hosts, and adult worms live mainly in the pulmonary arteries and heart. In domestic dogs, infection can cause severe cardiopulmonary disease.

The authors state that the finding indicates that D. immitis is established on Prince Edward Island and could spread among wild and domestic canids. Coyotes can therefore form part of the parasite’s transmission system in Atlantic Canada, alongside domestic dogs and other susceptible hosts.

The researchers argue that veterinarians in the Maritime provinces should consider locally acquired heartworm infection even in dogs without a travel history when compatible cardiopulmonary signs are present.

Sources and image credit

  1. Leaman, L. J., Graham, K. F., Jones, M. E. B., Greenwood, S. J., & Germitsch, N. (2026). First reported case of Dirofilaria immitis in a coyote (Canis latrans) from Prince Edward Island. The Canadian Veterinary Journal, 67(6), 622–625.

Image: Cephas — two wild coyotes in Grasslands National Park, Saskatchewan, Canada, 6 June 2023. Representative image, not the animal examined on Prince Edward Island. Cropped to 16:9. Source: Wikimedia Commons. · CC BY-SA 4.0 — https://creativecommons.org/licenses/by-sa/4.0/ · Source

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