Protecting Your Dog From Heartworms

Heartworm in dogs is a potentially deadly condition caused by parasitic worms transmitted through mosquito bites. These harmful invaders lodge in a dog’s heart, lungs, and blood vessels, compromising overall health and quality of life. Identifying early warning signs—such as coughing, fatigue, or weight loss—can help pet owners seek prompt veterinary care. According to veterinary experts, comprehensive prevention strategies have proven more effective and affordable than addressing advanced heartworm disease. By administering monthly preventive medications and scheduling regular heartworm tests, owners can protect their furry companions from unnecessary suffering. It’s also crucial to minimize mosquito breeding areas by eliminating standing water in yards and kennels. When combined with timely vet checkups, these steps reduce the risk of heartworm in dogs and promote lifelong well-being. Understanding the impact of heartworm and taking proactive measures ensures a safer, happier life for your beloved pet. Staying informed helps dog owners safeguard their pets.

It’s Heartworm Awareness Month. It’s also National Brunch Month, National Pecan Month, and National Poetry Month. While those are definitely more enjoyable topics, heartworms are more in our wheelhouse. Every dog owner should be aware of these harmful and ugly parasites. Continue reading as a local Cavan Monaghan, ON veterinarian discusses basic heartworm information.

Is It Necessary To Treat Dogs With Heartworm Prevention Every Month?

Absolutely! Fido’s heartworm prevention should always be kept up to date. The exact dosage schedule will depend on the product utilized. If he’s on a monthly schedule, then he’ll need it every month, of course, but there are now preventative products that can last six or twelve months.

People in northern locations, such as here in Canada, may decide to discontinue the preventative care throughout the winter. Although this is ultimately the owner’s decision, we would advise maintaining it, particularly as average temperatures rise. Ask your Cavan Monaghan, ON veterinarian for particular recommendations.

What Are the Signs of Heartworm Infections in Dogs?

You may not notice anything until the worms reach maturity, which can take up to six months. A dry, moderate cough is often the first warning sign. You may also notice that Fido isn’t particularly energetic.

Here are some of things to look for:

• Lethargy
• Weight Loss.
• Gums are discolored
• Nosebleeds
• Swollen Abdomen
• Persistent Coughing
• Loss Of Appetite
• Breathing problems
• Fatigue
• Lack of interest in play
• Exercise intolerance

If the infestation continues, more severe symptoms are going to develop. These can include fainting, staggering, and heart attacks. Unfortunately, sudden death is also possible.

Can Cats Contract Heartworms?

Yes. Kitties are less prone to infestations than dogs are, because their bodies are less receptive to worms. Don’t assume Fluffy is safe, though. Even just a single worm can permanently damage a cat’s organs. What’s more troubling is that cats may die suddenly, with no warning indications. Maintain your cat’s preventative care as well.

Do Other Animals Contract Heartworms?

Heartworm in dogs is a condition that affects any canid species. This includes not just Man’s Best Friend but also his cousins, the wolf, coyote, and fox. Cats and ferrets are also vulnerable. In fact, they have even been discovered in sea lions! While we’re on the topic of exotic pets, it’s worth noting that different animals have very different care needs. For instance, if you’re curious about other unique pets, you might find our article on What Should I Feed My Salamander? interesting. However, let’s get back to heartworm prevention for our canine friends.

Where Is Heartworm Most Common?

Heartworms are a risk anywhere mosquitos are present. Cases have been documented throughout North America. Unfortunately, this means Fido can become infected anywhere in the United States or Canada.

Are Certain Breeds More Susceptible To Heartworm Than Others?

Heartworms can infect any dog, at any age. Pups with thin fur may be more vulnerable since mosquitoes can bite them more easily. However, this does not mean that longhaired dogs are protected; fluffy canines are still vulnerable.

What Does the Data Say About Heartworms?

The data does not present a pleasant image. Here are a few of those numbers:

• Heartworms can be transmitted by over 70 different types of mosquitoes.
• Once a dog is affected, the worms take only 6 to 7 months to reach adulthood and begin multiplying.
• Female heartworms can grow up to 10 inches long. Male worms grow to be about 12 inches long.
• They look like spaghetti.
• The larvae can live for a month within the mosquito.

How Can Dogs Get Heartworms?

Fido can’t pick up heartworms directly from another dog. Indeed, the heartworm has enlisted the help of the world’s most annoying insect, the mosquito, to propagate itself. That implies dogs can be infected anywhere, including their own bed.

The mosquito will pick up heartworm larvae, also known as microfilariae, by biting an affected dog. When that mosquito bites another pup, the heartworms are delivered into their circulation. They grow quickly, and, within about six months, begin to multiply.

Can Heartworms Be Treated?

Therapy alternatives are accessible. However, these options can be costly and are also pretty harsh on poor Fido. To prevent his heart from becoming overstressed, your canine friend’s activities may need to be severely limited while he is receiving treatment. That means short walks and no strenuous play—that isn’t particularly fun for a pooch! In serious cases, pets may need to be kenneled.

An extremely severe infestation may necessitate surgery. Needless to say, this may be costly, and, again, is taxing on the pet. Your canine companion will also require close attention During his recovery time.

Have you heard the saying that an ounce of prevention is worth a pound of cure? That definitely applies here!

Can Humans Get Heartworms?

Heartworm in dogs is a significant concern, and it’s worth noting that humans can also contract heartworms. Although rare, this possibility highlights the need for preventive measures to protect both pets and their owners from heartworm infection.

How Do I Prevent My Dog From Getting Heartworms?

Staying on top of Fido’s preventative care schedule should be your first priority. This includes regular check-ups and vaccinations, which are crucial for your pet’s overall health. To learn more about keeping your furry friend protected from various health issues, including heartworms, check out our Veterinary Wellness Pet Vaccinations services.

Aside from that, you can also take some basic preventive steps against mosquitos. For example, you can utilize sonic repellers. Making your property more attractive to pollinators and bats can also assist. A single bat can consume 600 mosquitoes in one night! Standing water often becomes a breeding ground for mosquitoes, so empty buckets and plant pots after it rains.

When Are Dogs Most At Risk Of Getting Heartworms?

Summer is the most harmful season in the majority of places, because mosquitos are most active in hot weather. In the south, the risk is present all year.

The risk is decreased in the north during the winter months, although it remains present. Some mosquitos persist in the cold for longer than expected. (It’s also worth mentioning that higher average temperatures may raise the chance of infection in the winter.)

What Happens If I Forget To Give My Pooch Preventative Care?

Before you resume, you must get your canine companion re-evaluated. This is because the products that protect Fido from infestations do not destroy living worms. If your pet is already infested, preventative care will not protect him against the worms that are already in his system. For further information, ask your Cavan Monaghan, ON veterinarian.

How Often Should My Dog Be Tested for Heartworm?

Annual tests should suffice for the majority of pets. However, some dogs may require more regular tests. Keep in mind that certain pets will be at a higher risk than others. Spending time with other dogs will undoubtedly increase that risk. However, Fido does not even need to be in direct contact; a neighbor’s dog three homes down could spread the worms to him via mosquito.

Are Heartworms Getting More Common?

Unfortunately, yes. As with any sort of treatment or parasitic prophylaxis, some worms appear to be developing resistance. Also, it is becoming more popular for dogs to be adopted and transported from one region of the country to another, which has contributed to the increase in numbers.

That being said, there is no reason to panic. Just make sure to stay up with your canine companion’s preventative treatment and keep an eye out for symptoms. If you detect anything wrong, contact your veterinary clinic right away. The sooner an issue is diagnosed and treated, the better!

Heartworm in Dogs: 2025 Impact, Stages, and Treatment Risks

How exactly do heartworms affect the dog’s organs?

Heartworms primarily inhabit the pulmonary artery, where they disrupt blood flow and damage vessel linings. Over time, these parasites can migrate into the right ventricle, leading to an increased workload on the heart, reduced oxygen exchange, and potential enlargement or failure of cardiac muscles. Lungs often experience inflammation and reduced capacity, which may cause chronic coughing or respiratory distress. If left untreated, excessive worm loads place additional strain on the circulatory system, leading to blockages and impaired organ function. This systemic impact ultimately compromises overall health and can be fatal.

What is caval syndrome?

Caval syndrome is a life-threatening stage of advanced heartworm disease in dogs caused by adult worms clogging the heart and large vessels. This leads to severely compromised blood flow, serious organ damage, and potential cardiovascular collapse. Symptoms often appear suddenly and can include difficulty breathing, pale gums, dark urine, weakness, and collapse. Without immediate intervention, serious complications such as liver failure or shock can develop. Treatment typically involves surgical removal of the adult worms, combined with supportive care to stabilize the dog and address the underlying circulatory and organ damage.

Why is testing needed before starting prevention?

Testing is performed to confirm whether a dog has heartworms before starting prevention. Preventive treatments only target immature worms, so they cannot kill adult parasites already present. If an infected dog begins preventive medication without proper treatment, complications such as serious cardiac strain may arise. Symptoms might remain hidden until the worms have reached maturity, increasing health risks. Annual testing reveals infections early, allowing for timely interventions and helping prevent possible organ damage. This approach keeps the pet healthy while optimizing the effectiveness of prevention efforts. Regular screening also ensures that any emerging concerns are addressed promptly.

What are the different classes/stages of heartworm disease?

Heartworm disease is commonly grouped into four classes based on clinical signs and worm burden. Class I usually shows few or no symptoms, such as a mild cough. Class II involves moderate signs like occasional coughing or fatigue during activity. Class III produces more pronounced complications, including persistent coughing, difficulty breathing, and possible heart failure. Class IV, also called Caval Syndrome, emerges when a large number of worms block blood flow within the heart, leading to potentially fatal cardiovascular problems. Consistent testing and preventive measures reduce the chance of progression and foster a safer treatment process.

What are the specific risks and complications of treatment?

Heartworm therapy can be expensive and physically taxing on dogs. Medications may kill the parasites but can trigger inflammatory responses, including lung or organ damage from the dying worms. Dogs need restricted exercise to prevent strain on the heart, which often requires shorter walks and kennel rest in severe cases. Surgery may be necessary when infestations are advanced, posing further anesthesia and post-operative complications. Treatment can lead to stress for both the animal and caregiver, requiring close veterinary oversight and thorough follow-up testing to ensure the infestation is fully resolved.

Make An Appointment At Your Cavan Monaghan, ON Animal Hospital

Do you need to catch your dog up on his heartworm medication? Is Fido overdue for a checkup? Please contact us, your local Cavan Monaghan, ON pet clinic, at any time. We are dedicated to offering top-notch veterinary care.