April serves as Heartworm Awareness Month. The Meowing Vet shines the spotlight on heartworm disease, which can lead to heart failure in dogs and cats if not promptly detected and treated. Keep reading to learn how heartworms are transmitted, how the disease is diagnosed and treated, why cats are unique, and what you can do to prevent infection in your pets.
In a rush and only have 39 seconds? Then, please watch the video below provided by the American Heartworm Society about the gist of heartworm disease. Have a bit more time? Dig into The Meowing Vet’s in-depth article below!
(video courtesy of the American Heartworm Society)
Disclaimer: The risk of your pet acquiring heartworm disease varies among country and region. Please see the maps below and ask your local veterinarian if heartworm infection is a potential risk factor in your specific area.
Heartworm Transmission: the Role of Mosquitoes
(UGH! Why isn’t there a mosquito emoji when a gal needs one?!!!)
The scientific name for heartworms is Dirofilaria immitis. Thus, heartworm infection is often termed Dirofilariasis. Other Dirofilaria species* exist in nature, “cousins” to heartworms. However, Dirofilaria immitis poses the greatest risk to dog and cat health, and is also of concern in other wild canids which may serve as hosts for heartworms (such as wolves, coyotes, and foxes). Even pet ferrets are at risk of infection, so be sure to ask your vet about prevention.
*[Relatives include Dirofilaria repens, which infects the subcutaneous tissue (i.e. under the skin) of dogs and wild canids, as well as Dirofilaria tenuis, transmitted from infected raccoons, also infecting subcutaneous tissue. Please note that when referring to heartworms, I am not referring to Angiostrongylus vasorum (a canine lungworm also called the “French heartworm” that occurs in parts of Europe, including the U.K., Ireland, and France). Disease severity and treatment differs between this lungworm and true heartworm infection.]
Larval stages of heartworms are transmitted to dogs and cats by adult female mosquitoes of various species, including Aedes, Culex, Anopheles, and Mansonia spp. When these female mosquitoes act all “vampire-y” and bite infected mammalian hosts, they suck up (along with their blood meal) a particular larval stage of heartworm called the microfilaria stage. As depicted in the life cycle illustration below, the microfilaria (singular for microfilariae) develops further in the intermediate mosquito host over the course of 2 weeks, growing to the next larval stage, called the L3 form. Upon the mosquito’s next feeding, she will inject the L3 she’s been hosting into the bite wound of her next victim, which may very well be your dog or cat.
The L3 larva develops further in the definitive mammalian host, eventually moving from the skin into the bloodstream to the pulmonary arteries between the heart and lungs where they become mature adult worms. Adult heartworms can live up to 5-7 years (!!!) around your dog’s heart. If the infection includes both male and female worms, these adults mate, and the females give birth to a new immature larval stage, a microfilaria. Microfilariae develop within 6 months after your dog or cat is first infected with the L3 heartworm stage. Microfilariae may circulate in your pet’s bloodstream for up to 1 year until they are ingested by a hungry, wandering female mosquito vector to develop into an L3 form and start the cycle all over again.
Adult heartworms often carry a partner-in-crime: a bacteria called Wolbachia. These two organisms form a symbiotic relationship in the heartworm’s body, which provides a home to the bacteria; in turn, Wolbachia gives the adult heartworm some “special powers,” allowing the worms to thrive and reproduce more fruitfully inside the body of your dog or cat. Unfortunately, Wolbachia is thought to add to the dangerous inflammatory effect to the mammalian host in cases of heartworm infestations. More on Wolbachia in a minute…
[life cycle courtesy of… wait for it – tongue-twister alert! … DPDx, a website by the Centers for Disease Control and Prevention (CDC)’s Division of Parasitic Diseases and Malaria (DPDM)]
Global Occurrence of Dirofilaria immitis
Find your country or region in the map below to determine your pet’s risk of acquiring heartworm disease (HWD). Always consult with your local veterinarian for the latest prevalence data, as heartworm migration alters over time. Based on your region’s heartworm prevalence, preventive measures may be of utmost importance.
[image courtesy of Companion Vector-Borne Diseases (CVBD®) in collaboration with Bayer Animal Health; reflects data from 2012-2013]
As a practicing veterinarian in America, I am all too familiar with heartworm disease in this country, having treated several cases. Heartworms are endemic to all the contiguous states in the U.S. and are especially prevalent along the Gulf and East coast. Though mosquitoes may more commonly be seen in the spring, summer, and autumn, some mosquitoes remain active in the winter months. Moreover, some regions do not have a distinct seasonality for mosquitoes. Therefore, heartworm prevention should be used year-round, even in winter.
(image courtesy of the American Heartworm Society)
Diagnosis of Heartworms and the Importance of Annual Screening
Dogs with a low worm burden (meaning a low number of adult heartworms) may be asymptomatic while others with a heavier infestation may develop clinical signs ranging from mild to severe and potentially life-threatening.
Signs of potential heartworm disease in your dog: (more on cats shortly)
- Unexplained weight loss
- Cough (occasional to persistent, may include coughing up blood)
- Increased respiratory rate (tachypnea) or difficulty breathing (dyspnea)
- Exercise intolerance (meaning your dog fatigues more quickly when playing or going up stairs)
- Fainting (syncope)
- Collapse
- A distended abdomen (due to fluid accumulation, or ascites, secondary to heart failure)
Diagnosis of heartworm disease begins when your vet is suspicious of your dog or cat’s clinical signs, especially if he or she is not on a consistent heartworm preventative regimen. Your vet may also hear abnormal lung sounds or a right-sided heart murmur in your pet. Your vet will recommend a specialized heartworm test.
Several heartworm test modalities exist for dogs, including the WITNESS® Heartworm Antigen Test Kit by Zoetis, yet the SNAP® 4Dx® Plus Test by IDEXX is one of the most common and more reliable means. The SNAP® 4Dx® Plus Test kit tests a small amount of your dog’s blood for the presence of an antigen (immunologic particle) produced by female adult heartworms. In addition to testing for heartworms, the SNAP® 4Dx® also screens for several tick-borne diseases affecting dogs (Lyme disease, Ehrlichia, and Anaplasma; does not test for Rocky Mountain Spotted Fever). A similar test kit for cats also exists: the SNAP® Feline Triple Test, which detects heartworms, feline leukemia virus (FeLV), and feline immunodeficiency virus (FIV). (More on feline diagnostics below…)
If your pet tests positive for the heartworm antigen, your vet may wish to look at a blood sample (direct blood smear or Modified Knott’s test) under a microscope to search for live microfilariae swimming around; this can help your vet gauge your pet’s worm load as well as the timeline of infection. If your vet is concerned of secondary heart enlargement or other cardiovascular damage, he or she will likely perform thoracic radiographs (chest x-rays), which provide the most useful information of evaluating the severity of your pet’s heartworm disease. Bloodwork and/or a urinalysis may also be in order if your vet is worried of caval syndrome, a severe consequence of heartworm infection.
Classification of the severity of heartworm disease: (from less to more severe)
- Class I: minimally affected dogs with normal chest x-rays
- Class II: moderately affected dogs with occasional coughing and increased respiratory rate; have some x-ray abnormalities
- Class III: severely affected dogs with the aforementioned clinical signs; significant x-ray abnormalities
- Class IV: caval syndrome (see below for details) — an EMERGENCY!
Why is annual screening necessary if my pet receives heartworm prevention year-round? And why won’t my vet dispense a heartworm preventative without a test?
Excellent questions… and ones that I frequently receive from money-conscious and inquisitive clients. I assure you… most veterinarians are not trying to gilt you out of money by requiring an annual heartworm test before we provide you with another year’s supply of your heartworm preventative product of choice. Such testing is vitally important for several reasons:
- To ensure the efficacy of the products we prescribe. Veterinary pharmaceutical companies want to know that their products are working superbly over time without drug resistance issues emerging among mosquito populations. If for any reason a product is thought to have failed to protect a dog or cat, documented proof of purchase from a veterinary clinic as well as proof of an up-to-date heartworm test is required by the product manufacturer in order for you to receive possible compensation.
- To screen for other diseases, such as many tick-borne illnesses as can be detected by the canine SNAP® 4Dx® Plus Test or the SNAP® Feline Triple Test explained above.
- To make sure that you’re giving your pet his or her monthly preventative throughout the year. It’s not that we vets don’t believe you when you assure us that you’re definitely administering your pet monthly heartworm prevention year-round. You may be the most idyllic pet owner and client with whom a vet has ever worked. However, the potential to accidentally miss a dose or administer it at a wrong date exists. And sometimes, we may bathe our pet too soon after applying a topical heartworm prevention, washing it away and leaving our pet susceptible. And what if, unbeknownst to you, your dog or cat vomits up the last oral preventative given and is unprotected for a month? Just to be sure your pet was indeed protected year-round, an annual screening test is advisable.
- Because… if a pet that unknowingly has a heavy load of microfilaria due to an undiagnosed heartworm infection is administered a heartworm preventative, the product can kill many microfilariae at once. The sudden death of these immature worms can cause an overwhelming inflammatory reaction and anaphylactic shock, which can be deadly. Furthermore, the clump of dead microfilariae can cause a fatal thromboembolism, which may lodge in various blood vessels or travel to the heart or lungs.
Thus, administering heartworm prevention can be dangerous to dogs with an active heartworm infection unless specifically prescribed under your veterinarian’s supervision as part of a heartworm treatment regimen. (Heartworm-positive cats tend to have less microfilariae than infected dogs harbor, so infected felines rarely exhibit ill reactions following administration of a heartworm preventative. Therefore, your vet may suggest yet not require annual heartworm screening in your kitty before prescribing a supply of preventative.)
So please, please, please do not take the risk of declining your pet’s annual heartworm test recommendation! Please heed your vet’s advice out of concern for your pet’s health and allow for testing. Peace of mind is far worth the minor expense.
(video courtesy of the American Heartworm Society)
Interested in the scientific performance of the SNAP® 4Dx® Plus Test for dogs? Check out this informative video from IDEXX.
More Than Just Heartburn: Caval Syndrome
Heartworm infection is vitally important to promptly diagnose and treat to prevent potentially catastrophic and life-threatening cardiovascular failure. Vena caval syndrome, frequently called simply caval syndrome, can occur with a heavy infestation of adult heartworms (i.e. class IV of heartworm disease). As depicted in the photograph below, these mature worms can “clog” up normal blood flow through the heart and surrounding blood vessels, causing an enlarged heart with right-sided congestive heart failure (CHF). This causes fluid to accumulate in the abdominal cavity (ascites) and around the lungs (pleural effusion).
As previously discussed, weight loss, difficulty breathing (dyspnea), abdominal distension, coughing, fainting (syncope), and collapse are common features of caval syndrome. Bloodwork and urinalysis abnormalities may also occur, such as hemoglobinemia and hemoglobinuria (pink or blood-tinged urine) which occur when the adult heartworms cause the destruction of red blood cells as they circulate in the bloodstream around the worms (known as intravascular hemolysis).
Blood clots, blood vessel damage, and long-lasting pulmonary hypertension (high blood pressure in the arteries of the lungs) can also occur, the latter of which can worsen heart failure and lead to fluid development around the heart and lungs (pericardial and pleural effusion, respectively). Besides the cardiopulmonary system, other organs may also be damaged, including the liver and kidneys. In rare circumstances, adult heartworms have been found living in areas besides the heart and vessels, including the conjuctiva of the eye or even a testicle!
Caval syndrome requires IMMEDIATE treatment or else your dog will unfortunately die due to circulatory collapse. Treatment requires mechanical removal of the adult heartworms by a veterinary cardiology specialist. Sometimes, not all the adult worms are able to be retrieved despite the specialist’s best efforts. Unfortunately, many patients do not survive such an expensive procedure due to the severity of their illness or due to procedural complications (such as anaphylaxis or pulmonary collapse if an adult worm’s body breaks off instead of being removed in its entirety). Others may die shortly thereafter due to irreversible cardiac damage. Therefore, euthanasia is an all-too-common option for many pet owners. If your dog is lucky enough to survive intervention, his or her right-sided congestive heart failure (if present) will likely require life-long management with daily medications and occasional drainage of excess chest and/or abdominal fluid accumulation (thoracocentesis and abdominocentesis, respectively).
Click here for The Meowing Vet’s article on congestive heart failure in dogs and cats. ❤️
(image courtesy of the American Heartworm Society)
Treating Heartworm Infections
The abbreviation “AHS” often reminds people of the spooky TV show American Horror Story. But what’s even scarier? Heartworms! “AHS” also stands for the American Heartworm Society, which is constantly researching the latest, most efficacious, and safest methods of treating heartworm infections. Therefore, treatment guidelines may vary over time.
As of April 2017, the current heartworm treatment for dogs in class I-III of infection lasts for a total of 90 days, as displayed below. The American Heartworm Society has provided a handout with a timeline for pet owners whose dogs are undergoing heartworm treatment; click here to download.
Heartworm Treatment Timeline: (as recommended by AHS, last updated in 2014)
- Day 0: Diagnosis made. Start prednisone to be given on a tapered dose schedule for the next 28 days (prednisone is an anti-inflammatory steroid to reduce inflammation secondary to the impending killing off of microfilariae). (In the past, aspirin was prescribed to prevent blood clot development, but it is no longer recommended.)
- Day 1: Administer a heartworm preventative to start killing off some microfilariae and any L3 larvae present (to prevent them from maturing into new adults); the preventative will also sterilize adult worms and reduce their vitality. (Your vet may wish to observe your dog in-hospital for several hours to monitor for potential anaphylactic responses.) Start doxycycline to be given for the next 28 days in a row (doxycycline is an antibiotic to kill off Wolbachia, thus reducing the vitality and reproductive success of adult heartworms; it may also reduce inflammation).
- Day 30: Administer another dose of heartworm preventative. (As many of the microfilariae were likely killed off in last month’s dose, the potential for anaphylaxis is reduced yet still possible.)
- Day 60: Administer another dose of heartworm preventative. Drop your dog off at your veterinarian’s office for the day or overnight for the first injection of melarsomine. [Melarsomine (generic for Immiticide® or DIROBAN™) is an arsenical drug that kills adult heartworms; because it is arsenic-based, it has potential toxic effects in addition to the potential adverse anaphylactic reactions or thrombus formation as can occur when the worms die off. Your vet will advise close monitoring. Melarsomine is currently the only FDA-approved drug proven to kill adult heartworms.] Start prednisone again on a tapered course for the next 28 days.
- Day 90: Administer another dose of monthly heartworm prevention to be continued monthly thereafter. Bring your dog to your vet again for a 1-2 day stay for the second melarsomine injection.
- Day 91: Today your dog will have its third and final melarsomine injection. Prednisone will be prescribed on a taper for yet another month.
During the entirety of your dog’s treatment (and up to 6-8 weeks after the last melarsomine injection), exercise should be restricted. In severe infections, cage rest will be recommended for the length of treatment. Because of the risk of potential thromboemboli formation, which can travel to the lungs and be potentially fatal, we want to keep your dog as quiet as possible to reduce blood pressure and thus reduce this risk.
Your dog will be tested for heartworms again on days 120 and 271 (1 month and 6 months after the last melarsomine treatment) to ensure efficacy of the treatment. If your dog tests positive again (i.e. if a few adult heartworms survived the intensive 3-month treatment cycle), the treatment routine will be started once more.
If your dog is geriatric or has other health problems and your vet is concerned that the traditional melarsomine treatment protocol will be too taxing on your dog, potentially killing him or her during the therapy, an alternative “slow kill” option may be recommended. With the “slow kill” method, a monthly heartworm preventative is given continuously in the hopes that your dog will eventually test negative for heartworms; this can take many, many months. Though not ideal, this treatment method may be less toxic to your dog’s overall health; however, it is not without its own health risks as addressed prior.
As discussed previously, the management of caval syndrome (class IV) differs from less severe forms of heartworm disease. Caval syndrome requires immediate mechanical removal of adult heartworms by a specialist in a dire attempt to save your dog’s life.
The cost of treating a heartworm infection is typically greater than providing a monthly, year-round heartworm prevention for your pet for the duration of his or her lifetime. Therefore, the best “treatment” for heartworms truly is preventing disease in the first place. (Keep reading to learn more about various means of prevention…)
Heartworm Disease in Cats
Many pet owners think of heartworm disease as a dog-only problem. However, many fail to realize that their cats may be at risk too. Although cats are up to 20% less likely as dogs to develop heartworm disease, cats are indeed susceptible, particularly in high risk areas. Even indoor-only cats are at risk as a marauding mosquito carrying L3 may slip inside your home to find an all-you-can-eat buffet in your unsuspecting kitty. While dogs may be able to tolerate the presence of multiple adult heartworms in the vessels surrounding the heart and lungs, harboring just a single adult worm may be enough to kill a cat.
Cats are not the ideal host for heartworms, however, as heartworms would much rather prefer to live in the circulatory system of a dog if they had their way. For starters, fewer larvae are able to develop appropriately into adult forms, so heartworm-positive cats are less likely to have adult heartworms. If a heartworm does survive long enough to emerge into adulthood, adult worms do not typically live as long in cats as in dogs (2 years vs. 5-7 years), do not grow to be as long, and tend to have poorer fertility. Therefore, adult worms are less likely to produce microfilariae, causing the microfilariae load to be lower in cats in comparison to dogs. Heartworms may also travel to more “wonky” places in cats than in dogs, including the eye and brain (potentially causing blindness or a head tilt).
Fortunately, many cats do not exhibit any clinical signs following heartworm infection as adult worms may never have the chance to develop and cause cardiopulmonary damage. Some affected cats may show signs including unexplained weight loss, coughing (which may be mistaken for feline asthma), fast or aberrant breathing, lethargy, or chronic vomiting. However, if your cat’s natural host defenses against heartworm infection do fail, feline heartworm disease can be more severe and problematic in comparison to heartworms in dogs. Not only can a small burden of adult worms be deadly, but larval forms also carry high risks to your cat, and some cats may die of sudden respiratory disease with no prior clinical signs.
Diagnosing heartworm disease in cats can be more difficult than in dogs. Clinical signs may not be present (if so, watch out for increased respiratory rate or effort in your kitty as well as signs of open-mouth breathing or panting like a dog, which is often an indication of an emergency). Furthermore, no single test will detect all heartworm cases in felines. Since adults are rare, antigen tests (ex. WITNESS® Heartworm Antigen Test Kit or SNAP® Feline Triple Test) may be falsely negative. Microscopic analysis of blood may also be unfruitful since microfilariae are uncommon. Your vet may suggest a special antibody test instead, which measures your cat’s immune system’s production of antibodies in response to heartworm exposure; however, sometimes this test can be falsely positive.
Unfortunately, once your cat develops heartworm disease, no current medical treatment exists as melarsomine is too dangerous to administer to cats due to toxicity and a greater probability of inducing a fatal thromboembolism. Some vets may prescribe the steroid prednisolone chronically to mitigate the inflammatory effects of the heartworms and reduce clinical signs in early stages of the disease; while this medication is not curative, some cats have been able to survive heartworm infection by outliving the adult heartworms’ shortened lifespan. (Monthly heartworm prevention should be administered monthly throughout this duration to prevent re-infection.) Mechanical removal of adult worms in feline patients in caval syndrome may be attempted with varying success, yet as the feline heart is comparatively smaller than most dogs, this procedure is very difficult and risky.
Therefore, euthanasia is sadly elected in these situations. Instead, I urge you to choose a monthly heartworm prevention to administer to your cat year-round if you live in a heartworm-heavy area. Remember… prevention is key!
(video courtesy of the American Heartworm Society)
For information on vaccines, flea and tick control, and deworming, read The Meowing Vet’s articles on preventative medicine for…
Puppies and Dogs
Cats and Kittens
Heartworm Prevention is Like a Blast from the Past
Why are monthly oral or topical heartworm preventatives like a Throwback Thursday (#TBT)? Preventative products actually “kill backwards” by destroying L3 larval stages that may have infected your pet within the past 45-60 days, thus preventing L3 from maturing into adult worms. Bottom line is: heartworm preventatives work retroactively by preventing heartworm larvae from developing into harmful adults; these products do not, however, actually prevent mosquitoes from transmitting an L3 larva to your dog or cat.
Any heartworm preventative (HWP) should always be purchased from a veterinary clinic or with a veterinary prescription. Obtaining a product from your vet allows for product quality control as well as overseeing your pet’s safety. Always choose a veterinary-grade product as over-the-counter (OTC) and natural products lack proven efficacy and safety.
Puppies and kittens should be started on monthly heartworm preventatives around 6-8 weeks of age. If you adopt an older puppy or dog who has not been on heartworm prevention prior and is over 6 months of age, your vet will require a heartworm screening test before administering a preventative. Why the magical age of 6 months? Think back to the heartworm life cycle. It takes microfilariae 6 months to develop after your pet is first infected with L3 larvae from a mosquito bite. And remember, the death of microfilariae by administering a heartworm preventative can cause life-threatening thrombi or an anaphylactic reaction. These risks serve as yet another reminder of the importance of annual heartworm screening tests for dogs over 6 months of age.
A plethora of products exist to prevent heartworm disease in dogs and cats, including various oral, topical, and injectable options. Common active ingredients include the drug class macrolides (a.k.a. macrocyclic lactones): ivermectin, selamectin, milbemycin oxime, and moxidectin. Bonus? Monthly administration of these products also control many GI parasites (such as roundworms and hookworms) as well as some lungworms, acting as an automatic monthly dewormer!
(The list of heartworm prevention products discussed below is by no means an exhaustive index. After this article is published online, always ask your local vet about the latest products on the market in your specific country.)
For dogs, common topical products include Revolution® and Advantage Multi®. Canine oral selections encompass Heartgard Plus®, Interceptor®, Sentinel®, and Trifexis®. The aforementioned topical and oral products are administered monthly (every 30 days), year-round. A longer-lasting injectable formulation, ProHeart®6, also exists and is administered to your dog by your veterinarian every 6 months… perfect if you fear you’ll forget to give a monthly product!
Mosquitoes near heartworm-positive dogs have been shown to host a greater number of heartworm larvae than other mosquitoes. Thus, heartworm-positive dogs pose a significant health risk to nearby dogs in their household, neighborhood, daycare, or kennel. So please be a responsible dog owner and administer your dog a consistent heartworm preventative… not only to protect your own dog’s health but the life of other people’s beloved animals as well as nearby wildlife.
Ivermectin-based heartworm preventions should be avoided in collie breeds and collie crosses. Collies frequently carry a mutation in the MDR-1 gene, which allows certain drugs such as ivermectin to pass out of the bloodstream into the brain, potentially causing toxicity to the central nervous system. Discuss product choices and dosing with your vet to provide safe heartworm protection for your collie.
Though canine Vectra 3D® does not kill larval stages of heartworms transmitted to your dog within the past month, this product does repel mosquitoes in the aims of reducing your dog’s risk of transmission overall. Ideally, Vectra 3D®, typically used for flea and tick control, should be paired with another heartworm prevention at this point in time. Although a version of Vectra® is available for cats, special care should be taken when using canine Vectra 3D® on dogs in close contact with cats as the ingredients can be toxic to cats. Cats in contact with Vectra 3D® intended for dogs may experience neurological issues ranging from salivation, muscle tremors, and seizure activity. If you suspect your cat has ingested or been topically dosed with canine Vectra 3D®, seek immediate veterinary attention.
Less heartworm prevention products are currently on the market for cats, but speak with your vet about either topical (Revolution®, Advantage Multi®) or oral (ex. Interceptor®) varieties to protect your kitty from heartworms. These products should also be given monthly, year-round. So mark your calendar!!!
Other means of heartworm prevention include environmental mosquito control. The CDC recommends using screens on open doors or windows to prevent mosquitoes from entering your home. Furthermore, empty standing pools of water around your home once weekly as mosquitoes lay eggs in stagnant water. To repel mosquitoes from your dog, speak with your vet about Vectra 3D®. Always consult with your veterinarian before using human-grade insect repellents on your pets, especially on cats, as some ingredients may be toxic to pets. For more information on how to prevent mosquito bites, visit this resource by the Centers for Disease Control and Prevention (CDC).
All these veterinary product options making your head hurt?! Download our handy-dandy charts comparing the most common flea, tick, and heartworm preventatives available for dogs and cats in the U.S., Canada, U.K., Ireland, Australia, and New Zealand.
Can Humans Develop Heartworm Disease?
The answer is “yes” and “no”. Humans can potentially be abnormal hosts, becoming infected with larval heartworms transmitted by feeding mosquitoes. However, the human body is not an ideal environment for heartworms, so the larval stage does not mature into adult worms.
Dirofilaria immitis larvae often do not survive migration through the insect bite wound in the skin into the bloodstream. However, if the immature stages survive this migration, the larvae can cause small calcified (mineralized) nodules or granulomas (focal areas of inflammation) on the lungs, known as coin lesions. These coin lesions may show up as an incidental finding on thoracic radiographs (chest x-rays) where they sometimes can be mistaken for cancer, leading to further diagnostic tests for distinguishing.
Typically, no clinical signs associated with heartworm infection occur in humans. Uncommonly, some people may develop transient coughing, fever, chest pain, and occasionally the accumulation of fluid buildup around the lungs (pleural effusion). However, cardiac failure is not likely. Rarely, people may experience ocular, brain, or testicular ectopic lesions.
Remember those other Dirofilaria “cousins” of heartworms we discussed at the very beginning of this article? Dirofilaria repens is a more common cause of human Dirofilariasis in Europe (not existing in the U.S.), causing granulomas (those inflammatory nodules previously mentioned) to form under the skin.
Treatment includes surgical excision of either the pulmonary or skin lesions. If you are concerned with your own health, consult your personal physician.
– Maranda Elswick, DVM
The Meowing Vet hopes we fully convinced you of the importance of monthly, year-round heartworm prevention for your pets if you live in or travel to an at-risk area. If you have additional questions about the significance of heartworm disease and control, ask your local vet or visit the American Heartworm Society’s website. Please share this important article with your dog-, cat-, or ferret-loving friends! ❤️
