When Is Heartworm Treatment Done?: A Comprehensive Guide With 9 Facts

    heartworm treatment

    Heartworm treatment is something that is done on living beings that contract heartworm disease which is basically worms make a home in the heart of their hosts and just cause issues like any other disease.

    They are just doing their jobs, what they are supposed to and were born to do. Honestly, why such a fuss humans? Jokes aside, these heartworms can be the cause of very serious issues in any living being, although their tricks do not really work on all animals, but in some animals like cats and dogs, it can very well even be fatal.

    That is the reason that we need to be aware of these creatures or parasites. You might think that anything or anyone that lives in your or your pet’s heart would be a good thing, right? Well, not when they are quite literally living inside the hearts.

    These heartworms live in the heart of animals and can even spread to other organs, blocking them, but I will give you more information on that later. The heartworm parasites can affect even humans.

    This piece of information can be a bit worrying for you because as I said, this disease can be fatal for dogs and cats. So does the same apply to us humans too? Can we die from this disease as well? You will have to read this whole article to find out. Before I write about how heartworm treatment can be done, it will be a good idea for you to understand other things.

    I will be talking about what heartworms are, what problems they cause and in which living things, how they come to be, how heartworm treatment can be done, and a lot of other things that will help you understand this issue better. So fasten your seatbelts.


    What Is A Heartworm?

    Are you wondering why we are talking about heartworms when we are supposed to be talking about the disease caused by them and heartworm treatment? Well, as I said, before talking about the disease caused by this heartworm and its treatment, it is always better to know what we are dealing with.

    Dirofilaria immitis is a scientific name for heartworm. However, it is also known as dog heartworm, the reason being it most commonly targets dogs as their host. In the United States of America, out of 10 million dogs, more than 14% of dogs were found infected by heartworms.

    Heartworm is not like any other worm but a lot different and dangerous for your pet’s life. Heartworm is a type of roundworm which is categorized under parasites. It is a fine thread-like worm that chooses your pet as its new host.

    The heartworm, as the name suggests, can attack the heart of the host animal which can be fatal. But there is more to it. We will talk about the infection in a detailed manner later in this article. Let us see if heartworm can affect your pet or not.


    Hosts Of Heartworm

    As we have seen, one most common target as a host is dogs but do heartworms attack other animals too? Well, they do target most of the animals. The most common hosts of heartworm are dogs and cats. In this article, we will be focusing on these two animals as they are the most common pets.

    Let us see a list of all animals which can be a host for heartworm.

    • Dog
    • Cat
    • Jackal
    • Wolf
    • Coyote
    • Fox
    • Ferret
    • Raccoon
    • Bear
    • Sealion
    • African leopard
    • Human
    • Beaver
    • Reptiles

    Among these, dogs, cats, and reptiles like guinea pigs are widely accepted as pets. Thus we are most concerned about heartworm disease and heartworm treatment associated with these animals.

    Being aware of hosts is important as these are the real sources that can spread the disease or infection. The heartworms are always transmitted from host to host.

    But wait, did we just mention humans in the list of hosts of heartworm! No need to panic as a human, being a host of heartworm is something that will happen in an extremely rare case. Now let’s see what heartworm disease actually is.


    What Is Heartworm Disease?

    Heartworm disease is a disease caused by a parasite known as Dirofilaria immitis i.e heartworm. These worms live not only in the heart but also in the lungs and blood vessels of the host animal.

    Pets affected by these heartworms will suffer from lung disease, heart failure, or cause defects in other organs. These worms affect the pulmonary artery and adjacent large blood vessels greatly. As these heartworms directly attack the vital organs, this disease can be fatal.

    This disease was first found in the United States of America and later on got passed on to other nearby countries. The transmission takes place from host to host which means these heartworms can get transferred from say a random infected street dog to your pet dog.

    The transmission occurs through the medium of mosquito. There is no way heartworm disease can get transmitted from dogs to dogs directly as the heartworms are wound inside the pet’s body. Thus, this disease mostly spreads during mosquito season.


    Life Cycle Of The Heartworms

    heartworm treatment

    Now that you know what heartworms are and what kind of hosts they affect, it is time for me to explain to you the life cycle of these heartworms. It is essential that you understand everything about this disease before we even get to talking about the heartworm treatment process.

    The life cycle of heartworm is a bit complex. As I said before, this parasite depends on mosquitos that act as a kind of a medium between two hosts of the parasite and gets transferred to the body of a new host through them.

    Mosquitos are the most important part of the life cycle of heartworm as they help it acquire a new host, even though it is unknowingly. There are a lot of mosquito species that can transmit this disease from one host to the other. As many as 30 species can work as the intermediate host for these worms.

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    As I said, this disease gets transmitted via mosquitos, to be specific, female mosquitos, who bite a dog or cat or whichever animal that is already hosting these worms and in doing so, ingest microfilariae through the blood they consume.

    These microfilariae that the mosquitos consume, develop in the body of the mosquito for over 10 to 30 days. After they have developed enough to get transferred to a new host, they will move from the gut of the mosquito to the parts of its mouth.

    When the mosquito bites another animal, these worms will enter them and complete their maturing process. After these infective larvae are transferred from the mosquito to the new host, they will spread through the blood vessels to the heart. After that, they will become adults after maturing thoroughly and reproduce within 6 to 7 months of their entering the host.

    Now, before jumping to the heartworm treatment, let us see what symptoms we can expect in case your dog, cat, or even guinea pig has been infected by heartworms.


    Signs of This Disease In Common Animals

    Heartworm disease is not limited to a single animal and hence its symptoms, as well as heartworm treatment, can vary somewhat from animal to animal. However, the damage in all the animals is fatal due to the nature of the heartworms.

    As the dog, cat, and ferrets are the most popular pets, medical researchers have given more attention to them in terms of looking for symptoms as well as finding out the best heartworm treatment practices.

    Based on the medical research and treatments being practiced around the world, I am covering possible signs indicating heartworm disease in these 3 popular pets you will be most concerned with.



    heartworm treatment

    We already know that these heartworms are a kind of parasite. The specialty of parasites is that they consume the nutrients gradually over time. What this means is, the damage caused by parasites, in this case by heartworms is gradual and not instant.

    Therefore, the symptoms cannot be seen in the early stages when your dog has just been infected. This is one of the reasons that makes heartworm treatment difficult which results in the increased fatality of heartworm disease.

    Anyway getting back to the symptoms of heartworm disease in dogs, as we discussed in early-stage your dog may or may not show any strong signs. But as time passes and the heartworms get deep into the system, we get to see some prominent signs.


    Early Stage Of Infection

    In the early stage, signs include a mild but constant cough probably due to infection of heartworms into the lungs. Due to internal discomfort your dog may try to avoid any exercises, as the most energy is being consumed by this parasite.

    Your dog will try to spend the least possible energy and will stay in one place for most of the time. This will also result in fatigue as the daily activities of your dog will be greatly reduced. This is probably the best noticeable symptom as most dogs are always hyperactive and excited.

    Another set of signs which will indicate heartworm disease is the loss in appetite followed by weight loss. No single sign should be considered a symptom of heartworm disease. If you spot all or most of the signs mentioned above then you can conclude that it’s time to get heartworm treatment done for your dog.


    Later Stages Of The Infection

    As the heartworm grows inside the host’s body, in this case, your dog’s more serious and critical signs of infection are visible. These signs cannot be ignored and require immediate heartworm treatment before it’s too late.

    If the heartworms grow inside the heart, there are greater chances that as infection increases, these heartworms can cause heart failure. Adding more to it, these heartworms have the potential to block some of the veins and arteries. This will result in the swollen belly of your dog as the fluids will get trapped in the abdomen.

    Another challenge for heartworm treatment is if the heartworms are more in number, they can block the main arteries that carry blood to the heart. This will risk your dog’s life as it can lead to a cardiovascular attack.

    The symptoms in this critical phase include a change in color of urine to dark brown, labored breathing, and pale gums. If you see any of these signs, it might be already a little late to begin heartworm treatment. The only heartworm treatment to be done at such a stage is surgery to remove the blockage.



    Let’s admit it, sometimes the behavior of cats can be really unpredictable. Thus detecting signs of heartworm disease can be really difficult. Therefore, we will be focusing only on the prominent signs of infection.

    heartworm treatment

    Early Stage Of Infection

    The intensity or fatality of heartworm disease in cats is more severe. But the signs of infections in the earlier stage are somewhat similar to the ones found in dogs. It includes symptoms like coughing or sometimes frequent vomiting.

    Another sign includes loss of appetite and weight loss, the reason being the same as the ones we discussed in the case of dogs. Cats might also experience sudden attacks similar to asthma attacks.


    Later Stage Of The Infection

    As these parasites get bigger and stronger after living for a long enough time on host organs, more severe signs can be noticed. Your cat having difficulty in simply walking can be one of the first alarming signs indicating that it’s time for heartworm treatment.

    Some other serious symptoms include fainting or unexpected seizures or they may suffer from fluid accumulation in the abdomen. However, in some unfortunate cases, there might not be any initial signs but still can cause the sudden death of a cat due to heartworm disease. This does not mean to scare you but there are such cases.



    heartworm treatment

    Ferret, another domesticated animal that shares a lot of similarities with a dog. Ferrets are actually a type of polecat. But still, the cause of heartworm disease, symptoms, and even heartworm treatment shows some kind of similarity with dogs instead of cats.

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    Comparing a ferret with a dog, a ferret is a relatively smaller animal and thus has a smaller heart. Not just the heart, but this small creature has smaller organs as well but the size of the heartworms remain the same, be it a dog or a cat or a ferret.

    A small number of heartworms can greatly affect a ferret. Like, in dogs they don’t get much affected with a few heartworms but in the case of ferrets, they will immediately show signs of heartworm disease.

    A single worm can infect the respiratory tract of a ferret causing symptoms like coughing or rapid breathing. Other symptoms include lethargy because of parasites and the indication will be fatigue and tiredness.

    Open-mouth breathing and pale blue or muddy gum-colored fur can indicate heartworm disease too. If you notice any such symptoms, heartworm treatment from your vet is recommended.


    Where Is Heartworm Disease Found?

    This canine heartworm disease is something that can be hard to cure. The heartworm treatment can be costly sometimes. But when it comes to the lives of pets, money should not matter that much.

    Heartworm treatment might be difficult to do but the heartworms are not very considerate parasites, they just spread their legs wherever they can, well they do not have any legs but you get my point.

    These canine heartworms spread this disease across every country they can get into and do not follow international border rules. If they were considerate enough to do that, Covid-19 would have never left Wuhan. Jokes apart, the parasite spreads wherever they find a host.

    In the United States, this disease used to be only limited to the southern and southeastern areas. Most cases used to be reported in a 150-mile radius of the Gulf of Mexico and the Atlantic Ocean coastline and it could be found near the Mississippi River and its various tributaries as well.

    That used to be the case a while back but now, this disease has spread to a lot of regions including California, Oregon, and even Washington. This disease can also be found in Canada and especially in regions where the mosquito population is very high.

    The high mosquito population places include coastlines in a lot of provinces. The largest number of this disease can be found near the southern Great Lakes. The heartworm treatment cost is not very less as compared to the US either, it is almost the same there too.

    The factors that affect the increase of this disease include mosquitos, climate, presence of reservoir animals, etc. When the mosquitos actively feed, the chances of your pet getting this disease gets very high. That happens in temperatures around 50 degrees F.


    How Is Heartworm Treatment Done?

    Now that you have read all about what heartworms are, which animals they affect, and other such things, it is time that we go to the main topic of discussion and that would be the heartworm treatment.

    Heartworm treatment, as I said, is not very easy to do and it costs a hefty bit of money too. Before the heartworm treatment starts, one or more blood tests will diagnose the heartworm disease.

    After that, more tests will be carried out to determine whether it will be safe to perform the heartworm treatment on the dog. There are a lot of diagnostic procedures that are performed before the treatment starts and they are:

    1. A serological test for antigens done for adult heartworms and this test is performed on a blood sample and the heartworm treatment is done later.
    2. Chest radiographs i.e X-ray tests which are recommended to be done in dogs that have this disease. This is done to assess the total extent of what damage the heart and lung have undergone before the heartworm treatment is carried out.
    3. Bloodwork, i.e. complete blood cell count and the biochemistry of the blood is tested that is performed before the heartworm treatment and they help determine what kind of damage the organs have undergone.


    How Is The Heartworm Treatment Carried Out?

    When it comes to heartworm treatment, there are a lot of risks that are involved in the process that can make the treatment very difficult. But you should keep in mind even in the case of many risks being involved, the fatality rate is very low.

    There is a new drug that is used to do the heartworm treatment that does not have many side effects and it has a very good success rate that makes more than 95% of the treatments being done successfully.

    Earlier, the drug that was used to do the heartworm treatment used to have a lot of arsenic and it had many side effects. However, the new drug has solved a lot of problems. It has been observed that when the diagnosis of heartworm disease is done, most of the dogs have a very advanced stage of this disease.

    What that means is that the heartworms have been present in the body of dogs or animals for a very long time. And they have been present in the body of the animals to cause a lot of damage to the lungs, blood vessels, kidneys, liver, and obviously the heart.

    Sometimes, some of the dogs have the disease in such an advanced stage that it is safer to treat the damaged organs than it is to kill the heartworms. The dogs or animals who are in this condition might not live more than a few weeks or a month.

    If such is the case with your pet, the vet is going to advise you on what is going to be the best approach for heartworm treatment.


    How Is Heartworm Treatment Performed On Adult Heartworms?

    As I said, if the dogs or pets are in very advanced stages of the disease, they might not live long because the heartworms can’t be killed and that is because the heartworms have grown into adults.

    You should keep in mind that despite it not being safe to kill adult heartworms, the task can be done. There is an injectable drug that is available that can be used to carry out this heartworm treatment. This drug is called melarsomine which is used to kill adult heartworms.

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    This drug is helpful in killing heartworms that have made their homes inside the heart and in the surrounding blood vessels. This drug is injected into the bodies of the animals using multiple injections and the number of injections will be determined by the vet.

    Your vet will tell you all about the schedule of the injections. You should know that mostly, the animals will receive the first injection and will then have a month of rest and then another two injections will be given to it which will have a day’s gap between them.

    Many of the dogs are also given something called doxycycline which is an antibiotic that is used to fight potential infection with the bacteria Wolbachia that will go on to inhabit the heartworms.


    Heartworm Treatment For Microfilaria

    As I mentioned, a drug will be used to kill adult heartworms. What you should also know is that along with that drug, the pet is also going to get a drug that will be used to kill microfilariae that are the heartworm larvae.

    When this drug is being given to your pet, you will be required to stay at the hospital so that the doctors can observe the health of your pet. The drug for the microfilaria would be administered either before or after the heartworm treatment drug for adult heartworms is given. After their treatment is done, your pet will have to start a preventive course.

    In recent times, there have been a lot of drugs that are used to kill the microfilariae in heartworm treatment. It depends on the condition of your pet as to what drug the vet is going to use. Your pet will need to rest after the heartworm treatment has been carried out.


    Heartworms In Humans

    heartworm treatment

    Heartworm disease in the case of humans turns out to be a lot different than that found in any animal. The reason is simply that the structure of the human body is complex but superior to animals.

    Immunity is another factor that makes the intensity of heartworm disease significantly less than that of animals. However, it does not mean that the disease and heartworm treatment should be ignored in any scenario.

    Before getting into it, you must be wondering if heartworm disease is so rare in humans, how does it get transmitted to humans in the first place? Well, the question is valid and there is a satisfactory answer too.

    The only chances of you getting affected by heartworm disease are if you have a pet dog or a cat and your pet is infected by heartworms. In such a case, the disease may get transmitted from a dog host to a human. But you see this is a quite rare scenario of your pet and you, both getting infected by heartworm disease.

    This is a rare scenario, still getting yourself checked if your dog has been affected by heartworm disease is a smart decision any day. Though note that, it can be deadly for your dog but for you, not really.

    Now, without further ado, let’s get straight to the causes of heartworm disease in human beings as we already know a lot about what causes heartworms to enter into an animal’s body.



    The causes of getting yourself infected by heartworm are not anything different than what we have seen earlier. These are the same mosquitoes that infect our pets and later pass on these heartworms to us.

    Heartworms as a whole never get transmitted from one body to another as it is impossible to do so. Instead, they get transmitted through the transfer of blood in the form of heartworm larvae from one host to another, here from a pet to a human. In case you are interested in scientific term, heartworm larvae are also called microfilariae

    Once they get into the bloodstream of a new host, they begin to reproduce themselves and start growing in number. However, unlike animals, the heartworm larvae never really get matured into full-grown heartworm in humans. Instead, the defense system of the human body kills the larvae.



    Coming to the symptoms of heartworm disease, there are a few distinctive symptoms whereas others are more common for other diseases too. Let’s take a quick look at all the symptoms.

    • Unusual cough
    • Coughing accompanied by blood
    • Pain in chest
    • Wheezing
    • Chills
    • Fever
    • The buildup of fluid around your abdomen
    • Round lesions that can be seen on chest X-rays

    However, it is not necessary that you will get any of the symptoms mentioned above but you still can be affected by heartworm disease. Consider taking heartworm treatment after consulting a doctor if you experience any of these symptoms.



    You may predict or conclude that you have been infected with heartworm disease, but doctors cannot begin the heartworm treatment unless it has been diagnosed and confirmed. Then how is this diagnosis done?

    As heartworm disease is an internal disease, the diagnosis has to be internal before beginning any heartworm treatment. Thus an X-Ray is taken as the first step of diagnosis to take images of your internal organs.

    If the X-ray shows lesions as dark spots near the lungs, then it is confirmed that you have been infected by heartworm disease and then your doctor can begin heartworm treatment. A lesion is also called a granuloma.

    These lesions are a result of inflammation marks which are caused when our immune system fights back with heartworm larvae. A tissue sample can also be taken for the purpose of diagnosis to further assist in the process.


    Conclusion | Heartworm Treatment

    Heartworms are not something that you should be too afraid of. It can be treated. Although heartworm treatment might cost a bit of money, it is worth it if your pet gets to feel better after the treatment is done.

    Heartworms are spread through mosquitoes and they can take up to 7 months to mature inside the hosts’ heart and then they will start damaging the heart as well as other organs in the body of the host.

    You will just have to take your pet who is suffering from any of the symptoms of heartworm disease to the vet and they will diagnose the disease and then go on to do everything that they can to help your pet.

    Keep in mind that you should take care of yourself and your pet as nicely as you can, after all, if life wouldn’t exist, nothing else would. It’s a matter of perspectives. So take care of your pet and yourself and look out for these parasites that live in your heart rent-free.

    If you think that I may have missed out on some points or if you have any suggestions, do not hesitate to mention them in the comments section.

    Till then, Stay Safe Stay Healthy!



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