Only by the bite of an infected mosquito. Thereís no other way dogs get heartworms. And thereís no way to tell if a mosquito is infected. Thatís why prevention is so important.
Heartworm disease has been reported in all 50 states. And the bite of just one mosquito infected with the heartworm larvae will give your dog heartworm disease.
Heartworm disease has not only spread throughout the United States, but itís also now found in areas where veterinarians used to say ďOh, we donít have heartworm disease.Ē Areas like Oregon, California, Arizona, and desert areas -- where irrigation and building are allowing mosquitoes to survive. And if you have mosquitoes and you have animals, youíre going to have heartworms. Itís just that simple.
It takes about seven months, once a dog is bitten by an infected mosquito, for the larvae to mature into adult heartworms. They then lodge in the heart, lungs, and surrounding blood vessels and begin reproducing. Adult worms can grow up to 12 inches in length, can live 5-7 years, and a dog can have as many as 250 worms in its system.
The only way heartworms are transmitted is through the bite of an infected mosquito. And even if an uninfected mosquito bit your infected dog, and then bit your uninfected dog the same night, he wouldnít transmit the parasite from one dog to the other. Thatís because when a mosquito bites an infected animal, the heartworm needs to undergo an incubation period in the mosquito before the mosquito can infect other animals.