Heartworm is a parasitic disease that can affect any dog regardless of age, sex or habitat. It is found in the southern parts of Canada and all of the United States. Heartworm is spread by mosquitoes and tends to have a higher incidence in areas heavily populated by mosquitoes. Dogs are considered the most common host for heartworms. However, heartworms may also infect more than thirty animal species (including coyotes, foxes, wolves, domestic cats, ferrets) and even humans.
What are heartworms?
Heartworms are parasites that live in the blood of a dog’s heart and adjacent blood vessels. They can grow from four to twelve inches in length, reach maturation 6 to 7 months after infection and live for approximately five to seven years. Adult heartworms living in the heart, produce offspring known as microfilariae which circulate in the animal’s blood. When a female mosquito bites an infected animal, it sucks out the blood containing the microfilariae. When the mosquito bites another pet, the infectious larvae are transmitted. In many cases the infected dog will not show symptoms in the early stages.
Heartworm is the most serious common parasite in dogs because it stresses the dog’s heart by restricting blood flow and also damages other internal organs. The heart may enlarge and become weakened due to an increased workload, and congestive heart failure may occur. Left untreated, the disease can be fatal to dogs.
Blood screening tests can verify the presence of heartworms. Ultrasound and x-rays are used to detect the disease in its later stages. Prompt detection prevents needless suffering.