The American Heartworm Society reports that more than one million dogs currently have heartworm disease, and approximately 85% of the dogs we take into rescue each year are heartworm positive.  Heartworm disease is caused by foot-long worms (heartworms) that live in the heart, lungs and associated blood vessels of affected pets, causing severe lung disease, heart failure and damage to other organs in the body.  Adult female heartworms living in an infected dog, fox, coyote, or wolf produce microscopic baby worms called microfilaria that circulate in the bloodstream. When a mosquito bites an infected animal, it picks up these baby worms, which develop and mature into “infective stage” larvae over a period of 10 to 14 days. Then, when the infected mosquito bites another dog, cat, or susceptible wild animal, the infective larvae are deposited onto the surface of the animal’s skin and enter the new host through the mosquito’s bite wound. Once inside a new host, it takes approximately 6 months for the larvae to mature into adult heartworms. Once mature, heartworms can live for 5 to 7 years in dogs.  Heartworm disease is a serious, progressive disease. The earlier it is detected, the better the chances the pet will recover. Once a dog has a well-developed infection, treatment requires expensive and painful injections into the lumbar region of their back as well as months of strict crate rest.

There are few, if any, early signs of disease when a dog is infected with heartworms, so getting your dogs tested yearly at the vet (even if they are on preventative) is crucial.  Monthly heartworm preventative is much less expensive than having to treat heartworms, and it is obviously better for the dog’s health and well being to not get infected in the first place.  This is why we require that all CBR dogs (as well as any other dogs in our adoptive homes) to be on monthly preventative and to be tested yearly.