July 19

Dog Health Part 6: Heartworms


If you have a dog, you might have heard about the parasite heartworms.  A potentially life-threatening parasite these worms are responsible for a significant number of  dog deaths every year.  Here is what you can do to prevent them.


It is important to understand how heartworms are spread, as they are a risk to all dogs.  A mosquito bites an infected dog, picking up the heartworm eggs in the blood.  These eggs hatch and mature into larvae while in the mosquito.  The next time the mosquito feeds; these larvae are passed into the new dog’s blood stream.  Once in a new host, the worms mature and make their way to the right side of the heart and pulmonary arteries.


There they breed, releasing their offspring back into the bloodstream to be picked up by the next errant mosquito.  Since mosquitoes are the main transmitter from one dog to another, dogs are most at risk during the summer months.  However, in the southern regions where there is little or no winter heartworm can be picked up year round.


To test for heartworm, all you have to do is take your dog into the vet for a small blood draw.  This is recommended to be done every 6 months, as this is how long it takes for the worms to fully mature.  The blood test only tests for the antibodies that the adult worms produce, so if it is a new infection it might not be picked up until a second blood test.


Even if your dog is on heartworm preventative they should be checked, as no preventative is 100% effective all of the time. In the case of a positive test, your vet may order additional blood work to see how progressed the infection is.  They also may order an x-ray or an ultrasound of your dog’s heart to check for the presence of adult worms.  Heartworms might also be discovered if you dog develops an irregular heartbeat or has an irregular EKG.


Treatment of an active heartworm infection can be dangerous for the dog.  The dog is brought into the vet where it is injected with a poison to kill the worms.  The dog must then be monitored over several days.

In some cases repeat injections maybe necessary.  The biggest concern with heartworm is that if all of the worms die and release from the heart at once they can clog the arteries and cause the dog to go into cardiac arrest.  Other dogs experience reactions to the medication.


Therefore, the best treatment of heartworm infection is to prevent it from occurring in the first place. Heartworm preventatives are available with a prescription from your veterinarian.  Most vets will require a heartworm test prior to dispensing medications.  Medications are available in a once a month treatment, either as a pill or topical application.

The pill form is often flavored to taste like a treat, so it is easy to give as a treat or mix in food.  Remember to keep all medications out of reach of your dog (and children) to prevent accidental overdose.


What most people do not realize is that heartworm preventatives are actually mini heartworm treatments.  When you give your dog a treatment, it kills off any larvae that the dog has been exposed to over the past month before they have the opportunity to mature and move into the heart.


Because of this, it is generally recommended to have your dog on heartworm preventative year round.  Many oral heartworm preventatives, like Heartguard or Interceptor also have the added bonus of treating several different intestinal parasites that your dog might have come in contact with over the last month as well.


Another way to help prevent heartworm is to reduce the number of carriers.  If you live in an area with many mosquitoes, have your yard sprayed regularly.  Do not leave containers of water sitting around, as these make prime breeding grounds.

If you have a pond on your property, consider treating it with a mosquito poison or installing a pump to circulate water.  Steer clear of marshy or swampy areas when out walking at these make ideal mosquito breeding grounds.


A little prevention goes a long way, so remember to protect your pet against heartworm this summer.  You both will be happier for it.


It is highly recommended that you test your dog for heartworms at the vet as often as every 6 months, especially if you’re in a warmer region of the world.

In the United States, each testing can cost an upward of $45, excluding preventative medication. Unfortunately, the costs only steeply rise from there if your dog is tested positive for heartworms, extending as high as $1000!

This is also the reason why it is highly recommended that good pet insurance be purchased as soon as you adopt your pooch. You can get a free quotation here to determine what you want covered for your beloved pooch!

about the author

Frank Harrigan

Frank loves tacos and dogs - the good, bad and ugly sides of dog ownership.

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