Heartworms are transmitted to dogs and cats by mosquitoes.
Heartworm disease develops when a dog or cat is bitten by a
mosquito carrying microscopic heartworm larvae (juvenile worms)
of a parasite called Dirofilaria immitis. As a mosquito feeds,
these larvae are deposited on the pet’s skin and quickly
penetrate the skin to begin their migration into the pet’s
bloodstream. The larvae migrate through the bloodstream and
tissues, eventually reaching the heart and lungs. Adult
heartworms can grow 10 to 12 inches in length and make their
home in the right side of the heart and pulmonary (lung)
arteries, often causing lung disease and heart failure.
Heartworm disease is a major health problem for dogs living in
the United States and throughout the temperate and tropical
regions of the world. Once thought to be only a disease of dogs
and other wild canids (foxes, wolves, and coyotes), recent
studies indicate that heartworm infection in cats is more common
then ever believed. Without the protection of a heartworm pre