This page quotes a published document. Everything below in quotation marks is copied word for word from https://capcvet.org/guidelines/heartworm/, published by CAPC and retrieved on 2026-09-16. The quotations are excerpts; the document itself is linked and is the authority. Nothing has been reworded.
This page quotes the Companion Animal Parasite Council guideline for Heartworm, section by section: the opening sentences of 8 sections, copied without change and linked to the guideline, which was retrieved on 2026-09-16. The guideline itself is the authority and carries the full text.
The guideline
Companion Animal Parasite Council, Heartworm, at https://capcvet.org/guidelines/heartworm/. Retrieved 2026-09-16. Each heading below is the guideline’s own, and the quotation under it is how that section begins. The full section, and the species tabs where the guideline gives them, are on the linked page.
Synopsis
CAPC Recommends Annual testing of all dogs for both antigen and microfilariae of heartworm. Protect all dogs from heartworm infection by maintaining on preventives year-round.
Life Cycle and Stages
Microfilariae reside in the blood of most, but not all, infected canids. Microfilariae (300-322 µm x 6.8-7.0 µm) are ingested by feeding female mosquitoes.
Disease
Live heartworms in the dog induce pulmonary endothelial damage, villous proliferation, and activation and attraction of leukocytes and platelets. Dead and dying heartworms induce thrombosis, granulomatous, and villous inflammation.
Prevalence
Surveys indicate that heartworm infections continue to increase in number and geographic distribution. The geographic expansion of heartworm infection is caused, in part, by increased efforts to re-locate and re-home dogs (see Drake and Parrish, 2019 in the reference section).
Diagnosis
All dogs, including those on heartworm prevention, should be tested annually using both antigen and microfilariae tests. In some areas, testing dogs twice each year may be indicated, particularly in dogs that are exposed to high numbers of mosquitoes for long periods.
Treatment
The goals of treatment are to address the clinical condition of the animal and to eliminate adult heartworms, and microfilariae. Any or all of the following may be medically indicated to stabilize dogs presenting with clinical heartworm disease: corticosteroid therapy fluid therapy diuretics vasodilators positive inotropic agents Dogs receiving a macrocyclic lactone should be maintained on preventive.
Control and Prevention
All dogs, regardless of their lifestyle, should be on year-round heartworm prevention. Limit contact with mosquitoes.
Public Health Considerations
More than 100 human cases of pulmonary dirofilariasis have been reported in the United States in the last fifty years. Most cases occur in regions where heartworm is common in dogs (see Lee et al , 2010 in the reference section).
Continue reading public health considerations on capcvet.org
Sources
- capc-heartwormCAPC · retrieved 2026-09-16
“CAPC Recommends Annual testing of all dogs for both antigen and microfilariae of heartworm. Protect all dogs from heartworm infection by maintaining on preventives year-round.” (Synopsis)
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