I am sorry to hear about Lucie testing positive for heartworms. I am a veterinarian, and will do my best to help.
Was the test confirmed by looking a drop of her blood under the microscope to look for baby worms, called microfilaria? If there are microfilaria, that confirms she has heartworms living inside her heart.
If she is positive, then you decide about giving the Immiticide injections (quick kill) or starting a course of an antibiotic called doxycycline
, and monthly heartworm preventative (slow kill).
There are advantages and disadvantages to both. The quick kill is more expensive, the injections are painful, and can have side effects. She has to be kept confined for a few weeks after the treatment. However, then the worms are dead sooner, and there is less chance of her having damage to her heart and lungs.
The slow kill method is less expensive, no pain involved, but takes 6 months to up to 2 years to work. During that time the worms, which are 6 to 8 inches long, can be causing damage to her heart and lungs, or possibly she could die before the worms are gone.
I usually take a chest Xray. If the Xray looks like the worms are causing changes to the blood vessels in the lungs, I might go with quick kill in my own dog. If the Xray is clean, if the dog is not coughing or losing weight, then I would probably go with the slow kill method. If there are outward signs of heartworm like weight loss or coughing, then I might go with quick kill.
So, no clear cut answer! Let me know if she is coughing, how big she is, and if you have any more questions.