Heartworm in Dogs

Heartworms are long, skinny worms that sort of look like spaghetti that live in the hearts of dogs and cause heartworm disease, which can be lethal. They are found all over the U.S., and many vets now recommend that you regularly give your dog heartworm medicine as a preventative, especially if there have been a lot of cases in your area.


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How do dogs get heartworms?

Dogs catch them through mosquitoes. They don't get them directly from other dogs. Part of the heartworm life cycle involves living as extremely tiny little creatures in the blood of the dog. They cannot mature any more until they live in a mosquito - when one bites a dog with the worms, it picks up the larva, which mature and migrate to the point of the mosquito's sucker so that when it bites another dog, they can then move back to the new dog and grow into adults in its heart.

They take a long time to develop into full adults, and it can take three or four years before an owner notices anything is wrong.

What are the symptoms in dogs?

Dogs with adult heartworms will have problems with their entire body, because the worms stop up the flow of blood. In essence, everything will start working wrong. The most common symptoms are persistent coughing, weakness, inability to exercise or move around as much as the dog used to, or fainting. All of these will get worse when the dog is active. The disease can progress as the dog gets more worms, eventually causing the heart or other organs to fail. Heartworm disease can cause sudden death during exercise or just because the flow of blood gets stopped up.

What is the treatment for dogs?

Your vet will give the dog a drug that will kill off the adult heartworms, and you will have to watch your dog closely during this period. It can be very dangerous for the dog because the worms are decomposing inside the dog and can clog up the blood vessels. Your dog will have to be kept calm and you have to stop it from exercising or moving around much. You will also need to contact the vet immediately if you see anything that seems wrong with it. The vast majority of dogs with heartworms are treated successfully, but some cases are more advanced, and if there has been damage to the organs already the dog may be too far gone to treat.

After about a month, your dog will get a second drug that kills the little larva worms swimming around in its blood. This is to stop more adults from growing.

Your dog may also be given other treatments for the symptoms, especially if there has been some organ damage. Sometimes the heart has been damaged and needs lifelong treatment to function.

How do I prevent heartworms in dogs?

For either dogs that have been treated successfully or for dogs that have never had them, you just get a chewable heartworm medicine. If your dog has been treated for adult heartworms, you NEED to do this for the rest of the dog's life. Reinfection would be extremely dangerous. One of the more popular ones is Heartgard Plus, which is just a chewable tablet you give to the dog. 

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