Quick recap: What are heartworms?
Heartworms are long, thin parasites that live in the heart and lungs of infected animals, including dogs. They would be the perfect cast for an alien movie. These parasites can grow up to a foot long and cause serious damage to a dog’s health if left untreated. But how dogs get heartworms in the first place?
Why is it important to understand how dogs get heartworms?
As a dog owner, it’s essential to know about heartworms so you can take the necessary steps to protect your furry friend. We cannot stress enough that heartworms are a difficult health issue for dogs, and early detection and treatment can make a huge difference in your dog’s health and quality of life.
In this article, we’ll cover the basics of heartworms, including what they are, how dogs get them, and how you can prevent and treat heartworm infections in your dog. So buckle up, and let’s get started!
You already know heartworms are long parasites (resembling spaghetti) that can grow up to a foot in length (30 cm) and live in the heart and lungs of infected animals, including dogs. They are a type of roundworm with the scientific name of Dirofilaria immitis and are transmitted through the bite of an infected mosquito.

How Heartworms Affect a Dog’s Health?
Heartworms can cause severe damage to a dog’s health if left untreated. The worms can clog the heart and lung arteries, leading to heart failure, lung disease, and other serious health issues. In severe cases, heartworms can even be fatal. We have an article about heartworm symptoms in dogs so that you can learn how to spot the disease in case you haven’t noticed yet.
What is the Life Cycle of Heartworms?
Heartworms have a complex life cycle that involves mosquitoes and dogs. When a mosquito bites an infected dog, it picks up the heartworm larvae. Then, when the mosquito bites another dog, it can transmit the larvae to the new host. Once inside the new host, the larvae grow into adult heartworms (inside the heart and in pulmonary arteries), have sex, and begin to reproduce. The cycle then repeats itself with more mosquitoes and dogs.
As a dog owner, you must understand the basics of the heartworm cycle. By knowing how heartworms are transmitted and the life cycle they undergo, you can better understand the risks and take the necessary steps to prevent your dog from becoming infected.
For example, understanding the role of mosquitoes in the heartworm cycle can help you take steps to reduce your dog’s exposure to mosquitoes and minimize the risk of infection. This could include using mosquito repellent, keeping your dog inside during peak mosquito hours, and ensuring your dog is on a monthly heartworm preventative medication.
Here is a summary of the heartworm lifecycle:
- A mosquito bites an infected dog and picks up heartworm larvae.
- The infected mosquito bites another dog, transmitting the larvae to the new host.
- Once inside the new host (the dog), the larvae grow into adult heartworms.
- The adult heartworms reproduce and create more larvae, which circulate in the infected dog’s bloodstream.
- The infected dog can be bitten by a mosquito, which then picks up the larvae and transmits them to another dog, starting the cycle over again.
You can quickly check the milestones of the heartworm lifecycle in this infographic:

More details on how dogs get heartworms?
The Role of Mosquitoes
You already know heartworms are primarily spread through the bite of infected mosquitoes. When a mosquito bites an infected dog, it picks up the heartworm larvae. The mosquito can then transmit the larvae to another dog when it takes a blood meal. In summary: mosquitoes are the primary vectors for the spread of heartworms in dogs.
Where do mosquitoes bite dogs?
Mosquitoes can bite dogs in any environment they are exposed. This can include indoors and outdoors and in any location with a hungry mosquito population.
Outdoors, dogs are often bitten by mosquitoes while playing in the backyard, going for a walk, or spending time at a park or other outdoor recreation area. They can also be bitten while camping, hiking, or doing other outdoor activities.
Indoors, dogs can be bitten by mosquitoes that have found their way into the home. This is more likely to happen during the warmer months when mosquitoes are more active. It’s important to keep windows and doors screened to minimize the risk of indoor mosquito bites and to use air conditioning if possible.
Dogs can be at risk of mosquito bites and subsequent heartworm infection regardless of where they are. By taking steps to reduce their exposure to mosquitoes and keeping them on a monthly heartworm preventative medication, you can help protect your furry friend from heartworm disease. In addition, a Vet can give you more recommendations during regular checkups.
In what parts of the body can mosquitoes bite dogs?
Dogs can be bitten by mosquitoes anywhere on their body where the skin is exposed (where there is less hair). Some common areas where mosquitoes bite dogs include:
- Their legs and paws, especially when they are walking or playing outside
- Their belly, as they lie down on the ground or the floor
- Their face and head, as they sniff around or lay their head down to rest
- Their ears as they are sensitive and can be easy targets for mosquitoes

Mosquitoes can easily reach the skin anywhere they have thin or short hair.
Mosquitoes are attracted to areas of the body where blood is close to the skin’s surface, which is why they often bite in these locations. Therefore, it’s essential to remember that all dogs are at risk of mosquito bites and heartworm infections.
How do you prevent dogs from getting heartworms?
Heartworms are a serious threat to your furry friend’s health, but the good news is that it is entirely preventable with the proper preventative measures. So keep your dog healthy and heartworm-free.
What are the leading measures to avoid a dog getting bitten by mosquitoes?
Take the following measures to avoid mosquitoes biting your dogs and help prevent heartworm infection:
- Use mosquito repellent: There are many types of mosquito repellent products in the market, like topic drops, sprays, and collars, specifically designed for dogs. These products can help keep mosquitoes away, reduce the risk of bites, and prevent heartworm infection.
- Keep windows and doors screened: By ensuring that windows and doors are properly screened, you can help keep mosquitoes from entering the home.
- Use air conditioning: Running the air conditioning can help reduce the number of mosquitoes in the home and make it less comfortable for mosquitoes to bite.
- Please keep your dog on a leash: Keeping them on a leash when they’re outside can help reduce their exposure because they won’t go exploring places with a high concentration of potentially infected mosquitoes.
- Keep your dog inside during peak mosquito hours: Mosquitoes are most active in the early morning and evening hours. By keeping your dog inside during these times, you can help to reduce their exposure to mosquitoes.
- Keep your yard free of standing water: Mosquitoes breed in standing water, so keeping your yard free of containers and other items that can collect water is essential. This cleanup also includes old tires, birdbaths, buckets, and other containers. Try to talk your neighbors into this action.
- Keep gutters and drains clear: Clogged gutters and drains can also provide a breeding ground for mosquitoes. Make sure these areas are clean and clear to prevent mosquito breeding.
- Use fans: Mosquitoes are less likely to bite in areas with good airflow. Using running fans outdoors or indoors can help to reduce the number of mosquitoes in the area.
- Plant mosquito-repelling plants: Certain plants, such as citronella, lemon balm, and lavender, are known to repel mosquitoes. Consider planting these around your home to help keep mosquitoes away.
- Use mosquito traps: Mosquito traps are devices designed to attract and trap mosquitoes. These can be an effective way to reduce the mosquito population around your home.
- Seek professional help: If you have a large mosquito population in your area, you may want to consider using a professional pest control company. They can provide effective solutions for controlling the mosquito population and reducing the risk of mosquito bites.
- Use heartworm preventatives: Besides avoiding mosquito bites, keeping your dog on a monthly heartworm preventative medication is one of the best ways to protect them from heartworm disease. A combination of heartworm larvae-killing products and mosquito repellents are highly effective, and commercial products we recommend are readily available
By taking these steps, you can help to reduce your dog’s exposure to mosquitoes and protect them from heartworm infection.
What are the main year-round preventive measures for heartworm?
Several year-round preventive measures can help protect your dog from heartworm disease:
- Monthly heartworm preventive medication: One of the most effective ways to prevent heartworm in dogs is to give them monthly heartworm preventative medication. These medications are available in various forms, including pills, chews, and topical treatments.
- Get your dog tested regularly: Regular heartworm tests are critical to prevention. Having your dog tested regularly can detect the problem early, treat the infection, and protect your dog’s health.
Talking to your veterinarian before starting any heartworm preventive medication is essential. Regular vet checkups and testing can help ensure the drug works effectively.
What are the main options for treating heartworms in dogs?
Even if you take preventive measures, your dog may eventually get heartworm. In that case, it is necessary to start a curative treatment.
The specific treatment plan will depend on the severity of the heartworm infection and the dog’s overall health. Your Vet will suggest the best options for your dog.
These are the main treatment options for heartworm in dogs:
- Adulticide therapy treats your dog with medications designed to kill adult worms. This treatment can only be administered by your Vet and involves a series of injections or oral medications.
- Surgery: In severe cases of heartworm disease, surgery may be necessary to remove adult heartworms from the heart and lungs. This is typically done in cases where the number of adult worms is too large for adulticide therapy to be effective.
- Supportive care: In addition to adulticide therapy or surgery, dogs with heartworm disease will require supportive care to help manage the symptoms of the disease and support their overall health during and after treatment. Support may include medications for pain management, cough suppressants, and drugs to support heart and lung function.
What are the risks of the adulticide option?
Adulticide therapy can be hazardous, especially for dogs with severe heartworm infections, as the death of the adult worms can cause blockages in the heart and lungs that can be life-threatening. Therefore, a veterinarian should closely supervise the treatment, sometimes under hospitalization conditions.
Can cause complications: Adulticide therapy can also cause other complications, such as lung inflammation, blood clots, and allergic reactions to the medications used. Your Vet can reduce the probability of complications by administering anti-inflammatory drugs and exercise-restricting your dog for about a month after each dose administration. The most common adulticide drug used is Melarsomine.
What are the risks of the surgery option?
Surgery is an invasive procedure that requires general anesthesia, which carries its own risks, such as complications from the anesthesia and the surgical procedure itself. In addition, it can be costly, as it requires specialized equipment, a surgical team, and general anesthesia, and there may be post-operative issues.
Your Vet can help you decide if surgery is the best course of treatment for your dog and ensure that any risks are carefully managed.
Final remarks
In conclusion, heartworms are a severe concern for dog owners, and it is essential to have a basic understanding of how dogs get heartworms and the best ways to prevent them.
By taking preventative measures, such as using monthly heartworm preventive medications, controlling the mosquito population, and regular Vet checkups and testing, you can help protect your furry friend from the harmful effects of heartworm disease.
With the correct information and support, you can keep your dog happy, healthy, and heartworm-free for years to come!
So don’t wait.
Start taking preventative measures today and enjoy all the tail wags, barks, and cuddles your furry friend has to offer.
Ready to take action and protect your furry friend from heartworms? Then head over to our comparison page, where you can compare several top heartworm prevention products and find the best option for your dog’s unique needs. Whether you’re looking for a monthly preventative medication, a natural alternative, or a product that provides additional protection against fleas and ticks, we have you covered. So don’t wait. Visit our comparison page today and give your furry friend the gift of heartworm protection!