J.C. Hardin, DVM
HEARTWORM TREATMENT involves risks. In most cases, the risk of NOT treating exceeds the risk of treatment however. Most dogs experience some discomfort at the injection sites. Patients MUST be confined for six to ten weeks (ideally indoors) after the first Immiticide injection is given (depending on which treatment protocol is being followed) to help decrease the risk of pulmonary embolism or thromboembolism (PTE) (dead worms and/or clots migrating to blood vessels in the lungs). PTE can be fatal. Most patients experience breathing distress with PTE. If PTE is suspected, hospitalization for a long period may be needed, often with oxygen supplementation, heparin injections, etc. Do not let your dog run, play, get excited, or otherwise be active for the six to ten week period following the first injection. Tranquilizers are sometimes needed. Some doctors advocate the use of low dose aspirin therapy during this period, but precautions must be taken. Doxycycline is advised before and during heartworm treatment to combat bacteria called Wolbachia that live in the heartworms and are released during treatment. For some severely affected patients, treatment with Immiticide is not an option, and low dose ivermectin is used instead, though there are still risks to this approach. Left untreated, heartworms are usually fatal to dogs.