Heartworm Treatment at Elgin Veterinary Hospital

By Emily Hoppmann, DVM

Heartworms are a deadly parasite spread to your pet through a single mosquito bite. Once an animal   has been bitten, the heartworm continues to develop inside of your pet until it is an adult. Most adult   heartworms are located in the arteries of the lungs and in the heart – causing irreversible damage the entire   time they are there. Just placing your pet on a heartworm prevention just keeps your pet from getting more   heartworms, while the heartworms living in the heart and lungs are continuing to cause damage. These   worms can live up to 8 years, be anywhere from 6-10 inches long and as big around as spaghetti. It does not   matter if your pet is infected with several hundred heartworms or just a handful – either way the damage they   do is fatal. If there is a large number they can actually take up an entire artery, blocking blood flow, and killing   your pet. If the heartworms do not cause a sudden death experience like this, then the damage that they do   causes a much longer, more painful death as your pet’s heart goes into heart failure and the lungs stop being   able to supply oxygen to the body – eventually causing your pet to die. We test for heartworms every year   because they are so prevalent in our area and we want to catch any potential infected pets early in the disease   process since symptoms of heartworms do not usually surface until the advanced stages of infection and   include coughing, weight loss and fatigue. Your pet does need to be on heartworm prevention, even during   treatment, so he does not get infected again. Also, treatment is not a cure – your pet can get heartworms   again if off of prevention. Luckily, medical advancements have made heartworm treatment so much safer   than it was even 10 years ago. Unlike in years past the medication given to kill the heartworms do not have   negative side effects on your pet – the real danger is the dying heartworms. That is why I always do a slow-kill   approach so that the amount of worms dying at any one time is less and it is vital to keep your pet confined   during treatment. It is the body over-reacting to the dying heartworms that can cause serious, even fatal   consequences, to your pet. This is more likely to occur if your pet is too active or is not confined. During the   three months of therapy I recommend using sedatives to decrease the danger of your pet being too active and   I insist that your pet be confined to a kennel or small bathroom.

The Slow-Kill Treatment Plan 
In order for me to provide the safest heartworm treatment, I make sure that the heartworms do not all   die at one time which can cause a fatal reaction as the body goes into shock due to the high numbers of   heartworms dying. Before treatment I recommend blood work and x-rays so that we can better determine   the risk of treatment, the amount of damage that has been done already, and what signs to watch for during   treatment and years down the line. Once the heartworm treatment process begins it consists of 3 steps. The   first step is an injection that only kills part of the heartworms, so that the body is less likely to have any   reaction. During this step your pet will be in the hospital monitored closely for 48 hours and given pain   medication and anti-anxiety medications to ensure a laid back pet! The next step in not for 30 days, but   during this time it is essential not to allow your pet to be active and to keep him confined. The second step is a   series of two injections spread out over 48 hours, killing the rest of the adult heartworms. During this second   step your pet will again be hospitalized and given pain medication and anti-anxiety medications to ensure a   pain and worry-free stay. Following step 2 all of the adult worms will die and they are not excreted outside of   the body, but are dissolved and absorbed like blood clots. This is the reason why it is so important that your   pet has no form of exercise for the entire 3 months of the heartworm treatment. Step three occurs 30 days   after step two and it is the simplest step – you simply bring your dog in to be given an oral medication that will   kill any immature stages of heartworms and the “baby heartworms” called microfilaria. After another 30 days   of rest and constriction, your pet is able to go back to living his normal happy life (and getting his monthly   heartworm prevention)!

The Four Steps for Treating Heartworm Positive Dogs

Step 1:  Step one involves blood work to look at what damage the heartworms may have already caused and how well a patient   will handle the drug used to treat the heartworms. Sedated radiographs of the chest will also be taken for the same   reason. This allows us to know how severe the disease is, which gives us a better idea of how a patient will tolerate   treatment and if there are going to be issues later in life due to the damage already done to the heart and lungs.  **This step is optional – it is against medical advice not to do the blood work and x-rays, but it is not a requirement for   treatment.**

Step 2:   A single injection given to start to kill the adult worms. During this step your pet will be in the hospital monitored   closely for 48 hours and given pain medication and anti-anxiety medications to ensure a pain and worry-free stay!   **Patient needs to come in by 8 – 8:30 am and will spend the night**

Step 3:  This step is 30 days after Step 2 and involves two injections over a 48 hour period to finish killing all of the adults. Again,   your pet will be hospitalized and given pain medication and anti-anxiety medications to ensure his comfort.  **Patient needs to come in by 8 – 8:30 am and will spend two nights hospitalized**

Step 4:  The final step is 30 days after Step 3 and is the easiest step by far! You simply bring your pet in and he is given an oral   medication to kill any immature stages of heartworms or “baby heartworms” called microfilaria.  During the entire 3 months of therapy your dog must be kept confined and cannot be active at all or there can be   serious, even fatal, consequences. We can provide sedatives if needed. Also, your pet needs to be on heartworm   prevention monthly for the rest of his life, even during treatment.