How to Treat Heartworm in Dogs

How to Treat Heartworm in Dogs
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If your dog is diagnosed with heartworm disease, he/she can likely recover fully with treatment. Learn about the different treatment options available here.

Heartworm disease can cause a lot of harm to your dog and is potentially fatal. The good news, though, is that treatment of heartworm in dogs is generally both possible and likely to be successful. Heartworm treatment is a fairly involved and lengthy process and so it is best to give your dog a monthly preventatitve like Trifexis to avoid them getting heartworm.

In most cases, heartworm is treated through a two-pronged operation: In one treatment adult heartworms are killed, and in another, the microfilaria, or baby heartworms, are killed. The order of these treatments varies and may be determined by the health of your dog, as well as the severity of the disease. Veterinarians will also prescribe medications that attack Wolbachia, which are themselves a parasite attached to heartworms.

Destroy Adult Heartworms

The adult heartworms – which can occupy the heart, lungs, and blood vessels – are killed with an adulticide. Melarsomine dihydrochloride, an arsenic-based poison, is sold under the name Immiticide.

For the treatment, dogs are given a series of three injections of Immiticide, administered by a veterinarian. Following each injection, dogs need rest and recuperation. During the recuperation period, it is very important that dogs rest and do not exert themselves, because excercise can be fatal at this point. Keep your dog safe after receiving an immiticide injection by having them be leash walked for the following six months. Mass quantities of heartworms are killed by the adulticide treatment, and these heartworms need to be safely absorbed by the dog’s body. Since the adult heartworms are present in the heart, there is a danger of an embolism, or blocked artery, as the heartworms are destroyed. Inactivity reduces this risk, allowing the worms to slowly be absorbed. The other two doses of Immiticide are also given by injection. Generally, doxycycline is also given along with the adulticide to eliminate the Wolbachia parasite.

Eliminating Microfilaria

In addition to getting rid of the adult heartworms, veterinarians will also attack the microfilaria, using Ivermectin, which can also be used as a preventative treatment for heartworms. Generally, using preventatives when there is a known infection is unsafe, since killing many worms at once can overwhelm a dog. Since Ivermectin kills the microfilaria slowly, the danger is averted.

Slow Kill Method

While not generally recommended, another method of handling heartworms is to only attack the microfilaria, leaving existing adult heartworms to die of natural causes. This is known as the slow kill method. It’s cheaper and does not require the rest period and debilitating adulticide. However, adult heartworms are innately dangerous to dogs, and complications from their presence within your dog could occur.


In extreme heartworm cases, dogs may develop Caval syndrome, with heartworms filling and then expanding out of the dog’s heart. If your dog develops this syndrome, surgery will be required to remove the worms. This is a more invasive and dangerous treatment, and should only be done for dogs who will otherwise not survive.

When it comes to heartworm, prevention really is the best medicine. Learn more about preventing heartworm here.

Heartworm Preventatives

Heartgard Plus
Iverhart Max
Tri Heart Plus

Related Content

Heartworm Medicine
How to Prevent Heartworm in Dogs
Heartworm Tests Explained

This information is for informational purposes only and is not meant as a substitute for the professional advice of, or diagnosis or treatment by,your veterinarian with respect to your pet. It has, however, been verified by a licensed veterinarian for accuracy.

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