Dogs get heartworms through the bite of an infected mosquito. The process works as follows:
- A mosquito bites a dog already infected with heartworms and ingests microscopic heartworm larvae called microfilariae circulating in the dog's bloodstream.
- Inside the mosquito, these microfilariae develop into infective larvae over 10 to 14 days.
- When the infected mosquito bites another dog, it deposits these infective larvae onto the dog's skin through the bite wound.
- The larvae enter the dog's bloodstream, migrate to the heart, lungs, and associated blood vessels, and mature into adult heartworms over about 6 to 7 months.
- Adult heartworms then mate and produce more microfilariae, continuing the cycle
Heartworm disease is not contagious directly between dogs; it requires the mosquito as an intermediate host to transmit the larvae. The adult worms can live in the dog’s heart and lungs for 5 to 7 years, causing severe damage and potentially fatal heart and lung disease
