Your Dog Has Heartworms

How to prevent hearing those words, and how I dealt with them when I did.

Happy national heartworm awareness month! Forgive the lengthy introduction, but before we delve into the subject of heartworms, I’d like share some of my personal experience on the topic.

I love my dogs. So, naturally, I take the steps my veterinarian encourages in order to take the best care of them that I can. Every year, they show up for their annual exam where I invest in all of the bells and whistles: vaccines, tests, nail trims, flea and tick prevention, heartworm prevention, etc. Nothing shocked me more than finding out that my King boy was heartworm positive at his yearly visit in January.

What? Heartworms? How could that even be possible?

We brought King into our home when he was a year and six months old. He captured my heart nearly immediately with his big smile and sweet soul. I never doubt that he’s happy to be an addition to our family, and I can’t imagine life without him. It still baffles me that we are his third home, but I’m grateful he ended up with us every day. First step, of course, was to take him to our veterinarian to get him checked out. At the time, he was underweight, and he suffered from extreme allergies. (We had no idea what we were getting ourselves into with that, but that’s a story for another day.) We were happy to receive a good report of a negative heartworm test, and we started him on monthly preventions after that.

Interesting fact about heartworm tests: they only show positive results for adult heartworms. Here’s the thing about the life cycle of heartworms: it takes heartworms six months to complete a life cycle. So, if your dog is tested before the heartworm has completed its life cycle to the stage of adulthood, the result of the test will be negative. (More on that later.)

Considering we didn’t have King in our lives for the first year and a half of his life, we weren’t sure of his previous heartworm history of testing and prevention. So, he was tested again six months after his initial visit. The test result was still negative, which gave us a huge sense of relief. He continued to take his prevention monthly on the same day of every month, so needless to say, a positive heartworm test was the lowest of worries on my radar. I mean, we were doing everything right, so why would we think otherwise?

Wrong. Fast forward to three and a half year old King at his annual vet visit. When our veterinarian walked back into the room, I knew something was off from the way she entered. A multitude of thoughts flashed through my mind instantly from “Something is wrong with him” to “Everything’s fine. You’re being ridiculous”. But when she set down the positive heartworm test, I was floored. My heart sunk as the reality set in. How he managed to get heartworms, we’re still not completely sure. While heartworm medications are extremely effective, some dogs can still contract them, though rarely. Regardless of how the infestation occurred, we are going through it now, so I wanted to share our experience, knowledge, and tips that we’ve learned, with the hope of helping someone else.

What are heartworms?

Most pet owners know that heartworms are bad news, but not many of us take the time to really research them in depth. I mean, that’s why we trust our veterinarian and their staff’s recommendations — because they do. While I’m sure your veterinarian will be happy to discuss the ins and outs of heartworms with you, it doesn’t always come up in your appointment, or you may not feel that you have time to get into an in depth discussion with the vet during your visit.

So, let’s start with the definition of heartworms.

The technical name for heartworms is Dirofilaria Immitis.

Dirofilaria immitis, also known as heartworm or dog heartworm, is a parasitic roundworm that is a type of filarial worm, a small thread-like worm, that causes dirofilariasis.

So, how did my dog get heartworms?

Basically, it all starts with a mosquito bite.

Adult female heartworms living in an infected animal produce microscopic baby heartworms called microfilaria that circulate throughout the animal’s bloodstream. When a mosquito bites an infected animal, it picks up those microfilaria. Those microfilaria then mature into infective larvae, and when that infected mosquito bites another susceptible animal, the larvae then enter the new susceptible animal through the mosquito’s bite wound.

Long story short, when a mosquito bites an infected dog with heartworms, it can then infect your dog with a simple bite.

Once your dog has been bitten by an infected mosquito, it takes about 6 months for the larvae to develop into adult heartworms (where they will show up on a heartworm test). Once they are adults, heartworms can live for 5 to 7 years in dogs.

Because of the heartworm’s long life span, each mosquito season can lead to an increasing number of worms in your pet. These adult worms living in the heart, lungs, and blood vessels can cause severe lung disease, heart failure, and damage to other organs in the body: all serious and potentially fatal conditions.

Heartworm tests and monthly prevention

According to the American Heartworm Society, detecting heartworms with a heartworm test at your veterinarian is important, because there are few, if any, early signs of heartworms. The test works by detecting the presence of heartworm proteins. Test results are obtained quickly, and if your pet tests positive, further tests may be ordered.

When should I get my dog tested for heartworms?

Puppies under seven months of age can be started on heartworm prevention without a heartworm test, since it takes at least six months for a dog to test positive after being infected. Although, puppies should be started on heartworm prevention as soon as possible. The American Heartworm Society recommends starting a puppy on heartworm prevention no later than eight weeks of age. Your veterinarian will be able to help you pick which heartworm prevention is safest for your puppy’s age and weight. Your puppy should be tested 6 months after your first visit, tested again 6 months later, and then only annually after that to ensure that they are heartworm-free. All dogs should be tested annually for heartworm infection.

Getting your dog heartworm tested yearly is important, even if they’re on heartworm prevention year-round, to ensure that the prevention is working properly. Heartworm preventions do have a very high success rate, but like we found out the hard way with King, some dogs can still get them. This can happen for several reasons: missing just one monthly dose, giving the medication late, your dog vomiting, spitting out the pill, or rubbing off the topical medication. Studies are also being done regarding rare, but possible, resistance. If you don’t get your dog tested, you won’t know your dog needs treatment.

As a pet owner, it’s important that you do everything you can to prevent heartworms in your pet. There are many type of heartworm preventatives including: chewable, flavored pills, topical preventions, and injectable preventions. You can work with your team at your veterinary office to select which product works best for your pet. The American Heartworm Society recommends that you use year-round administration of heartworm preventives to protect your pet. Despite what you read on the internet or hear from other owners, it’s important to understand that there are no “natural” products that can be used for either prevention or treatment. Always use FDA-approved products as recommended by your veterinarian.

Get prevention directly from your veterinarian

Our saving grace throughout this entire ordeal with King is that we have always gotten him tested as recommended, and we purchased our heartworm prevention directly from our veterinarian. Why, do you ask? Because if you follow the proper protocol outlined by the American Heartworm Association by following your veterinarian’s recommendations, the company that produces your heartworm prevention will more than likely cover the cost of heartworm treatment.

Many consumers don’t realize that the products you buy from your veterinarian are backed and guaranteed by the manufacturers. We were able to prove through his medical record that he had been heartworm tested as recommended, and that we had purchased approved products through our veterinarian that were being administered correctly. I say we, but honestly, our veterinary clinic did all of the work for us by communicating with the prevention company. This is so, so important, because treating heartworms can be very expensive. The process requires months of treatment and multiple visits to the clinic. Luckily for us, the company is covering 100% of King’s heartworm treatment, which we’re unbelievably grateful for. My fiancé and I just lost our jobs due to COVID-19, so I can’t imagine how we would pay for treatment out of pocket.

If you haven’t gotten prevention through your veterinary clinic, or maybe this is the first time you’re learning about heartworm prevention and treatment, there are other options available to you. Companies like Care Credit and Scratchpay are ways to make payments on veterinary medical bills. If money is an issue when purchasing prevention, it’s important to note that often the manufacturers of the products will offer exclusive saving opportunities when you purchase a product through your veterinarian. Many great deals and mail-in rebates are available, so be sure to ask the veterinary staff when purchasing. Most times, you end up getting a better price than if you bought online or from a pet store.

If you’re looking for convenience, the majority of veterinary clinics now have verified online pharmacies as well that are providing the same quality of products that they sell in clinic.

Treating a heartworm positive dog

Watching King go through heartworm treatment is one of the hardest things that I’ve ever had to do. Luckily, my veterinary clinic has been by our side every step of the way. We’re very fortunate to have a clinic that follows the guidelines lined out by the American Heartworm Society. I highly encourage you to use a clinic that follows those guidelines exactly, due to their guidelines leading in a 98% success rate for pets treated for heartworms.

If you’re about to start the journey of heartworm treatment with your pet, here’s what you can expect: If your dog does test positive for heartworms, your veterinarian will confirm the diagnosis with additional testing. Once your veterinarian confirms that your pet does indeed have heartworms, they will start the pre-adult heartworm treatment. Your veterinarian may recommend a course of antibiotics, heartworm preventives and steroids before beginning the actual adult heartworm treatment. These medications will help with any inflammatory responses in the body that your pet may experience due to the adult heartworm treatment. The heartworm preventative will be used to kill the microfilaria (baby heartworms) before starting the heartworm treatment that kills the adult worms.

The next step of treatment will be to start treating the disease. This will take several months and will require bringing your pet to the clinic several times for injections and monitoring. Melarsomine is the only drug approved by the FDA for treatment of heartworm infection in dogs. While there are some risks associated with this medication, most adult worms die quickly and will be eliminated in one to three months.

The hardest part of the process for us has no doubt been cage rest and drastically reducing King’s exercise. It has been extremely difficult to confine King to his kennel and small areas, but we know it’s the only sure way to decrease the chances of complications from treatment. It’s very easy to want to give in and let your pet potty off leash or play, but it is vital that you restrict their exercise the entire time they are going through treatment and for awhile afterward. You must ensure that they remain calm. Your veterinarian will let you know when your dog can resume normal activity levels again safely.

You may be wondering why rest is so important. While the injectable medication is doing its job of killing the adult heartworms in your pet, pieces of those dead worms can block blood flow and cause an inflammatory response. Excitement and exercise can increase blood flow to those blocked areas, which causes capillaries to rupture as the body is attempting to pump blood through those blocked vessels. That increases the chance off complications like coughing, breathing difficulties, and even death. It may seem sad to keep your pup confined during this time, but it’s important to think of it this way: keeping them calm is saving their life.

Slow Kill vs American Heart Society Protocol

I think it’s important to note, there is another type of heartworm treatment called “slow kill” that exists. Slow kill is often recommended due to it being less expensive than the treatment recommended by the American Heartworm Society. This form of treatment is more or less a birth control for the heartworms. It kills the microfilaria, but is far less effective at killing the adult worms. I won’t go in depth, but here’s a summary of why the AHS does not recommend slow kill treatment:

Slow kill treatment takes place over a year, or sometimes much longer, to achieve results. During that time period, the adult heartworms are still doing damage throughout your pet’s heart and lungs. It is far less effective in eliminating adult worms than Melarsomine. Plus, you run the risk of your dog being able to infect other dogs with heartworms while being treated. Slow kill also requires strict cage rest and exercise restriction throughout the entire period of treatment. If you think a few months of kennel rest is hard to watch, try years.

Rest time for recovery

Your dog going through heartworm treatment can be scary, but there are many ways you can help them recover safely and happily! Dr. Karen Baker highlighted some great tips in an article on How to Keep a Dog on Crate Rest Entertained. The first step, if you haven’t already, will be to create an environment that will aid your dog in resting and recovering. Using training, you can teach your dog to be calm in a certain spot, such as a kennel or mat. Have you pet lie on their spot and encourage calmness with gentle petting paired with a cue word that will let your dog know that it’s time to settle down. Once your pet starts relaxing, mark the correct behavior, and reward with training treats.

One thing that has really helped us through this experience is playing calming music. Training can be a great tool that you can utilize to not only keep your dog calm, but to stimulate your dog mentally (but not physically). Using clicker training to teach your dog simple and quiet tricks (such as “shake”) will help relieve boredom. Most of us are probably more able to relate to our pets on cage rest than ever with the recent quarantines. As you’re probably familiar, meal time is something to look forward to when you’re stuck at home. Do your pet a favor and make their meal time last as long as possible with a food puzzle. Although, please make sure that if you utilize a food puzzle, you’re selecting one that doesn’t encourage your dog to move their body around.

Another way to help with boredom is to let your dog chew on safe bones or toys. Antlers make a great, natural chew for your pet. Always supervise, and make sure to check with your veterinarian for the safest recommendation they have. Ensure that your chew choice does not encourage your pet to move their body around. The goal is to give them entertainment while keeping them calm. While the process of heartworm treatment can be disheartening and overwhelming, it is undoubtedly the best step toward your pet’s recovery. Hopefully, the majority of you reading this will never have to go through heartworm treatment with your dog. If your pet is one of the unfortunate ones like my King boy, I hope this gave you some more information, understanding, and some tips on getting through the process.