Heartworms in Dogs: Facts and Myths
WebMD separates the facts from fiction about canine heartworms.
Q: How can I prevent my dogs from getting heartworms?
A: For less than the cost of going to Starbucks for a weekly coffee, you can
prevent heartworm disease in your dog. There are monthly pills, monthly
topicals that you put on the skin, and there’s also a
six-month injectable product. The damage that’s done to the dog and the cost of
the treatment is way more than the cost to prevent heartworm disease. A year’s
supply of heartworm preventative will cost about $35 to $80, depending on a
Q: What are the symptoms of heartworm infestations in dogs?
A: Initially, there are no symptoms. But as more and more worms crowd the
heart and lungs, most dogs will develop a cough. As it progresses, they won’t be able to exercise
as much as before; they’ll become winded easier. With severe heartworm disease,
we can hear abnormal lung sounds, dogs can pass out from the loss of blood to
the brain, and they can retain fluids. Eventually, most dogs will die if the
worms are not treated.
Q: Once my dog has heartworms, what’s the treatment? How much will it
A: The drug that you treat with is called Immiticide. It’s an injectable,
arsenic-based product. The dog is given two or three injections that will kill
the adult heartworms in the blood vessels of the heart.
The safest way to treat heartworms includes an extensive pre-treatment
workup, including X-rays, blood work, and all the tests needed to establish how
serious the infection is. Then the dog is given the injections. With all the
prep work, it can run up to $1,000. But just the treatment can be done for
about $300 in some areas.
Q: Why do I have to keep my dog quiet during the several months he’s
being treated for heartworms?
A: After treatment, the worms begin to die. And as they die, they break up
into pieces, which can cause a blockage of the pulmonary vessels and cause
death. That’s why dogs have to be kept quiet during the treatment and then for
several months afterward. Studies have shown that most of the dogs that die
after heartworm treatment do so because the owners let them
exercise. It’s not due to the drug itself.
Q: If my dog is diagnosed with heartworms, can I just give him his
monthly preventative instead of having him go through treatment? Won’t that
kill his heartworms?
A: Studies have shown that if you use ivermectin, the common preventative,
on a monthly basis in a dog with heartworm disease, after about two years
you’ll kill off most of the dog’s young heartworms. The problem is, in the
meantime, all of those heartworms are doing permanent damage to the heart and