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Recognizing and Treating Heartworm in Dogs

heartworm symptoms in dogs
Vet Approved

This information is up to date and writtenin accordance with the latest veterinary research.

In my many years as a veterinarian, I’ve encountered numerous cases of heartworm disease in dogs.

This potentially deadly condition, caused by parasitic worms inhabiting the heart and pulmonary arteries of an infected dog, is as severe as it sounds. But here’s the silver lining:

Heartworm disease in dogs is entirely preventable.

In this article, we’ll unravel the mysteries of heartworm disease. We’ll delve into its causes, identify the symptoms, explore treatment options, and, most importantly, discover how to prevent it.

So let’s dive in, and explore how to ensure a healthier, heartworm-free life for your beloved canine companion!

What is heartworm disease in dogs?

Heartworm disease is a serious and potentially fatal condition caused by a species of parasitic worm called Dirofilaria immitis.

Unlike other parasites, such and fleas and mites, adult heartworms are much harder to detect as they reside in a dog’s heart, lungs, and associated blood vessels; often by the time an infected dog shows symptoms, it’s too late for them to make a full recovery.

So how does your dog get heartworm disease in the first place? The microscopic larvae of these parasites are transmitted into the bloodstream of dogs through the bite of an infected mosquito. Once inside the host, the heartworm larvae migrate to the heart and lungs where they mature into adults.

dog heartworm mosquito

This process takes approximately six months. Adult heartworms can grow up to a foot long and can live for five to seven years in the host. The adult female heartworms then reproduce, creating more larvae in the process.

Sadly, as you can imagine, the presence of these worms in these organs can cause lasting damage, impacting the dog’s health and quality of life even after the parasites are gone. Symptoms of heartworm disease may not show up until the disease has progressed to a point where treatment is no longer an option.

The good news is that heartworm disease is preventable with medication and early detection can lead to a better outcomes. Regular testing and preventive medicines are therefore crucial in keeping dogs protected

What are the Symptoms of Heartworm Disease in Dogs?

Heartworm disease can be insidious, meaning that the disease gradually progresses without noticeable symptoms in the early stages. However, as the disease advances, symptoms begin to appear. Here are some common heartworm symptoms in dogs:

  • Mild Persistent Cough

    Dogs infected with heartworms often have a dry, hacking cough. This is caused by the worms making their way into the dog’s lungs.

  • Fatigue

    Dogs with heartworm disease may become tired quickly after only moderate exercise or play.

  • Weight Loss and Decreased Appetite

    Infected dogs may not feel well enough to eat, leading to weight loss.

  • Reluctance to Exercise

    Dogs suffering from heartworm disease may show less interest in physical activities due to discomfort or fatigue.

  • Rapid or Difficulty Breathing

    As the disease progresses, dogs may suffer from rapid breathing or shortness of breath due to heartworm associated respiratory disease.

  • Swollen Belly

    As the disease progresses, fluid can accumulate in your dog’s abdomen due to heart failure.

  • Collapse

    In severe cases, dogs may collapse due to the strain on their bodies.

  • Allergic Reaction

    Some dogs may show signs of an allergic reaction like skin irritation and itching, although this is less common.

  • Caval Syndrome and Fainting

    As the heartworm disease progresses, the worms can block blood flow through the heart, leading to caval syndrome. This obstruction prevents normal blood flow through the right side of the heart, which can lead to life-threatening consequences.

  • Anemia

    The damage to internal organs and blood vessels can result in a both a loss of blood, resulting in pale gums and anemia.

It is important to detect heartworm disease early, as the American Heartworm Society suggests that symptoms may not be present until adult worms have established residence in a dog’s heart, which can take up to six months post-infection. This makes early detection crucial for effective treatment.

How do dogs get heartworm?

heartworm cycle in dogs

Dogs contract heartworm disease through the bite of an infected mosquito. When an infected mosquito bites an infected animal, it picks up microscopic baby worms known as heartworm larvae. These infective larvae are then transmitted to another dog when that same mosquito bites again.

The American Heartworm Society suggests that all wild canine species, such as wild dogs, foxes and coyotes, can serve as sources for these parasitic worms. This means your beloved pet could potentially be exposed to the infection even in urban areas with few mosquitoes.

Since heartworms are transmitted through mosquitoes, it’s important to test any pet that comes into contact with these insects. This includes pets that venture outdoors occasionally. Keep in mind that mosquitoes can find their way into homes, putting indoor-only pets at risk too.

The states with the highest numbers of incidences of heartworm disease in dogs were Mississippi, Louisiana, South Carolina, Arkansas, and Alabama, all states known for their humid climates

How do vets test for Heartworm Disease?

When it comes to heartworm disease, early detection is key. Veterinarians diagnose heartworm disease through a series of tests.

Blood Tests

The first step usually involves blood tests to detect heartworm antibodies and antigens (proteins produced by adult worms). This helps determine if an infection is present.

The American Heartworm Society suggests annual testing for all dogs, regardless of whether they’re on preventative medication or not. Even the best heartworm preventive methods aren’t 100% effective against heartworms in dogs.

Blood tests can also assess the function of a dog’s other organs which is particularly important when there’s suspicion that the infection has advanced significantly.

Radiographs and Ultrasounds

If the results of the blood test are affirmative, more diagnostic tests such as X-rays or ultrasounds may be done to observe any harm caused by adult worms living inside your dog’s body – particularly to assess the chest for signs of severe lung disease.

These imaging techniques allow veterinarians to visualize any damage caused by adult worms living in your dog’s body – particularly their hearts and lungs where these parasites tend to reside as per research studies.

How is heartworm disease in dogs treated?

dog heartworm treatment

If a dog tests positive, the first step veterinarians take to treat an infected animal is to kill adult worms living inside an infected dog’s heart. This involves a series of injections that contain medication specifically designed to eliminate these parasites.

It’s important to keep in mind that severely affected dogs might need hospitalization during this phase, as the death of the worms can cause significant inflammation and potential blockage of pulmonary vessels. Steroids and antibiotics like doxycycline are often used together to help minimize the side effects of the worms dying.

After dealing with adult heartworms, it’s time for the second stage – killing off any remaining infective larvae (also known as microfilariae) left behind by adult female worms. Veterinarians typically prescribe oral medications taken over several weeks which effectively clear out these immature parasites from your pet’s blood vessels.

Once both stages of heartworm treatment are complete, regular check-ups are necessary so vets can monitor recovery progress and detect possible complications early on. Follow-up tests will also be done periodically after treatment completion in order to ensure no new infections have occurred through mosquito bites; Infected mosquitoes act as carriers transferring infective larvae from one host another including wild canine species.

How successful is the treatment of heartworm disease in dogs?

The success rate of heartworm treatment is quite high. With the three-dose adulticide protocol, in conjunction with antibiotics and steroids, 98% of dogs will be cleared of heartworm infection.

However, for dogs with a more severe last-stage form of the disease, such as those suffering from heart failure or caval syndrome, the success rate is less favourable. Therefore a quick diagnosis is essential in giving your dog the best outcome.

How do you prevent heartworm disease in dogs?

Heartworm prevention is best achieved by using FDA-approved products that specifically target heartworms. These products require a veterinarian’s prescription and are typically administered monthly, either as a topical liquid applied on the skin or as an oral tablet.

Routine heartworm testing is also an important part of prevention. Regular check-ups can ensure early detection and treatment of heartworm disease.

There are some natural heartworm prevention methods mentioned like certain tinctures, but these should be used with caution and always under the guidance of a vet. It’s important to note that holistic solutions are not generally recommended for preventing heartworm disease.

When it comes to risk factors, it’s important to remember that any pet exposed to mosquitoes is at risk for heartworms. This includes pets that only go outside occasionally, and even indoor-only pets, since those pesky mosquitoes can find their way into homes too.

Puppies can have preventative medication for heartworm disease from as young as 6/8 weeks old. If your puppy is a little older (age 6 months plus) it’s important that they’re tested for heartworm disease before starting on prevention medication.

Please always consult with a vet for the best heartworm prevention plan for your specific pet.


Can heartworm disease in dogs be cured?

Heartworm disease can be cured, but the process is a bit lengthy, complex, and often expensive. With current treatments, upto 98% of dogs with heartworms are now able to be successfully treated

What are the first signs of heartworms in dogs?

The initial symptoms of heartworm infections in dogs can include a mild persistent cough, fatigue after moderate activity, and reluctance to exercise.

What are the signs of heartworm disease in dogs?

Signs of advanced or severe heartworm disease may involve difficulty breathing, swollen belly due to fluid accumulation, decreased appetite and fainting episodes.

Do dogs feel sick when they have heartworm disease?

Dogs with early stages of heartworm infection might not show any symptoms. However, as the disease progresses it can cause illness including lethargy and weight loss.

How long can a dog with heartworm disease live?

If left untreated, a dog infected with Heartworm disease could die within two years. The lifespan depends on various factors such as severity of infection and overall health condition.

If you’re serious about safeguarding your pet’s health against threats like heartworms, consider becoming part of our community at Pet Health Guru. We offer trusted advice on how to care for your pets effectively and responsibly. Join us today and ensure that man’s best friend stays healthy and happy!

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