10 Things Your Dog Needs You To Know About Heartworm Before It’s Too Late

Written by: Katie Haller

September 22, 2015

Heartworm disease. The majority of us know it’s a thing. A bad thing. But only the minority seem to know exactly how it works, where it comes from, and why prevention is so crucial.

This is what you need to know.

1. Heartworm disease is spread by mosquitos. 


Like we needed another reason to hate them.

Mosquitos are considered the “intermediate host”, which means they only carry the larvae until they become infective. The larvae basically just crash there temporarily until they reach their final destination, your dog.


Unfortunately, it’s hard enough to catch a mosquito on our own skin, let alone our dogs. When a dog is bitten, the dog becomes the definitive host, which is where the larvae grow up and become adults, living in your dog’s heart, lungs, and blood vessels.


The adult female heartworms release their offspring, or microfilariae, into the dog’s bloodstream. When a new mosquito bites the dog, it becomes infected. Then, this mosquito finds another innocent dog, and repeats the process.

2. Heartworm Disease has been found in all 50 states. 


While it is most common along the Atlantic and Gulf Coasts from Gulf of Mexico to New Jersey and along the Mississippi River and it’s major tributaries, it has been found in all 50 states.

3. Heartworm Disease is not contagious. 


Phew. Now you don’t have to worry about catching anything.

4. Heartworms can be up to A FOOT LONG. 


Male heartworms generally reach 4-6 inches, while the females can grow to be 10-12 inches.  We don’t want to gross you out too much so we won’t show you an actual picture, but if you’re curious about what heartworms look like, look no further than a cup of Ramen noodles…

5. The number of worms living inside a dog is called the worm burden. 


The average number of worms is 15, but worm burdens can rage from 1 worm to 250 worms. 3 DIGITS.

I know buddy, I know.

6. Symptoms are classified into four stages, and some are nearly impossible to detect.


Stages 1 & 2 consist of an occasional cough and tiredness. The most alarming thing about this is that these symptoms are not particularly alarming. Most dogs have a bit of a sluggish side, especially if they get enough exercise.


Stage 3: Symptoms include loss of body condition, cough, tiredness, trouble breathing, and signs of heart failure. An x-ray of the chest will reveal changes to the heart and lungs.


Stage 4: Also known as Caval Syndrome. In this phase, blood is physically blocked by a large mass of worms and cannot travel to the heart. The only treatment option is immediate surgical removal. This is a very risky surgery, and even with the surgery, many dogs with Caval Syndrome do not make it. Not all heartworm disease turns into Caval Syndrome, but it does cause permanent damage to the heart, lungs, liver, and kidneys.


7. Treatment can be very risky. 


There are FDA-approved drugs. The first, Caparsolate Sodium, is injected into the dog’s veins. However it is not currently manufactured in the U.S. The newer drug, called Immiticide, is injected deeply into the back muslces of dogs with stabilized stages 1, 2, & 3 heartworm disease.

Treatment can be extremely toxic to a dog’s body and has been known to cause life-threatening blood clots. Of course, it’s impossible to put a price on your dog’s life, but for those of us who have financial strains, multiple visits to the vet, bloodwork, x-rays, hospitlization, and series of injections are extremely costly.

8. The best treatment is PREVENTION. 


A bit of a cliche, but only because it’s true. The scariest thing about this disease is that by the time symptoms are noticeable, it might already be too late. Luckily, there are many options for prevention, all of which require a prescription from a vet.

Most products are given as a monthly tablet or topical liquid. Another product is injected by a veteranarian every 6 months. Since there are several options, it’s best to talk to your vet about which one is right for your dog.

9. There are several types of tests for heartworm disease. 


The most common is called an antigen test. This detects specific proteins called antigens produced by female heartworms. This test can detect heartworms that are at least six to seven months old, but generally can’t detect anything less than five months.

The other tests discover the larvae, microfilaraie, which would indicate that adult heartworms are present.

10. Giving a heartworm preventative to a dog infected with heartworms can be harmful or deadly.  


Puppies under 6 months can start prevention without a heartworm test.

However, if your dog is older than 6 months, they must get tested for heartworms before they can start a prevention program. If a dog is given heartworm prevention while infected with heartworms, it can kill the microfilariae, which shocks the dog’s body and can even cause death.

It is extremely important to stay on top of prevention treatment. If you miss a dose, your dog can easily become unprotected. The moral of the story is to start early, so your dog can grow up to be happy and healthy.

Trust us, your pup will thank you.



Featured image via @violetdragonfly

Source: United States Food and Drug Administration

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Written by: Katie Haller

September 22, 2015

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