Heartworm treatment should be much safer for dogs now that a new medication, Immiticide (rx), is available to veterinarians. This medication has fewer side effects and kills a higher percentage of heartworms than Caparsolate (rx), which has been the only medication available until now. Heartworms live in the heart and the large blood vessels which go to the lungs from the heart. When they are killed by medications, a danger of embolism results if the dead worms block the flow of blood to the lungs. This is a common cause of death during a heartworm treatment. This risk still exists with Immiticide, but to a much lesser extent, due to differences in the timing of heartworm deaths. In addition, Immiticide does not appear to damage the liver or kidneys, which was sometimes a problem with Caparsolate.

If your dog has heartworm disease and you have been putting off treatment due to the higher risk of complications associated with Caparsolate, it would be a good idea to call your vet and discuss this new treatment. Dogs feel better after heartworm treatment and their expected life span is the same as a dog that was not affected with this parasite if treatment is successful. Even though there is a small risk of death during treatment, it is still usually a much better choice than not treating for heartworms.