Home Health and Care Parasite Treatment and Prevention Heartworms in Labradors: Treating, Preventing Heartworms in Dogs

Heartworms in Labradors: Treating, Preventing Heartworms in Dogs


Heartworms in Labradors? What are heartworms and how do dogs acquire them?

Dirofilaria immitis or the dog heartworm is a very serious and potentially deadly health issue. Heartworms are parasites that can live in the dog’s heart, lungs, and blood vessels. They can grow up to a foot long or even longer. Affected dogs experience breathing difficulty, organ damage, and heart failure.

heartworms in Labradors

Heartworms in Labradors are transmitted via mosquito bites. A dog can get the parasite through mosquito bites that transmit it from an infected dog to a healthy dog. Since Labradors love exploring outdoors, they are at greater risk. But do note that even indoor dogs can get heartworms. Since dogs are natural hosts for heartworms, these parasites can live inside a dog until they mature into adults. They can even mate while they are inside the host’s body and produce eggs.

If left untreated, the heartworm population can increase to several hundred – causing severe damage to the dog’s heart, lungs, and arteries that can lead to death. It is very important to have a dog with heartworm infestation treated as early as possible. Even with treatment, dogs who have been infested with heartworms for a long time may suffer from irreparable organ damage and lower quality of life.

How Can Heartworms Hurt Your Labrador?

When heartworms mature, they can clog up your Labrador’s arteries leading to the lungs. Aside from that, they can also irritate the lining of the blood vessels that lead from the heart to the lungs. The blockage of arteries will cause your Labrador’s heart to work harder to pump blood through the lungs to receive oxygen.

The larger the heartworm population, the harder the heart works. This could eventually lead to heart enlargement and cause the organ to fail due to the overwork.

Symptoms of Heartworms in Labradors

Heartworms in Labradors are silent killers. Signs of this disease are often overlooked and passed off as signs of aging and other diseases. Most of these symptoms of heartworms in Labradors may not appear until the worms reach their maturity – usually 6 months after transmission.

Dogs infected with heartworms may show one or more of the following signs.

  • Soft and dry cough
  • Lethargy or exercise intolerance
  • Weight loss and lack of appetite
  • Labored or rapid breathing
  • Protruding chest
  • Unexplained allergic reaction
  • Collapse
  • Pneumonia
  • Bleeding in the nose
  • Rare seizures

How are Heartworms in Labradors Treated?

It is important to determine the severity of the infestation first before treating heartworms in dogs. Veterinarians may suggest blood tests to detect the various stages of infection, including examining the blood sample and using a test kit to scout for antigens of adult heartworms. There are also other lab tests that detect abnormalities in your Labrador’s internal organs associated with the heartworm infestation. These may include the following.

  • Radiographs (X-rays): X-rays can detect enlargement or swelling of the heart or lungs, inflammation.
  • Ultrasound: An Echocardiography can also help determine heart health for treatment. This test can also detect the presence of heartworm presence.
  • ECG: ECG can detect abnormal heart rhythms and enlarged heart chambers.

Other tests may also be required to determine if there are damages to other internal organs, as the results are vital to finding out if the dog is healthy enough for treatment.

Pre-Adult Heartworm Treatment

Once your Labrador is diagnosed with heartworm disease, the vet may recommend heartworm preventatives, a course of antibiotics, and steroids before starting the actual treatment for the adult worms.

A bacterium called Wolbachia can be present inside the heartworms. When heartworms die, they release that bacteria into the dog’s body, So, antibiotics can be prescribed to kill such bacteria. If not treated, the presence of Wolbachia may cause the dog’s body to create an immune response. This reaction can worsen the dog’s health condition, as it can also cause lung and kidney inflammation. Veterinarians often prescribe doxycycline, as research showed promising results of this antibiotic in heartworm-infected dogs.

Do not be surprised if your veterinarian prescribes heartworm preventatives at the beginning of the treatment. Because heartworm treatment can only kill adult worms, veterinarians recommend heartworm preventatives to kill smaller heartworm larvae.

Second Stage Heartworm Treatment

Once your Labrador is done with Step 1, he should be ready for the actual heartworm treatment. This takes 1 to 3 months and consists of a series of drug injections that kill the worms.

A drug called Melarsomine is approved by the FDA to treat adult heartworms in dogs. This organic arsenic compound is injected into the dog’s back or lumbar muscles.

It is important to let your dog stay in the hospital or clinic on the days the injections are given. This is to ensure that he does not have any serious reactions following the injection of the drug. The vet may also prescribe steroids to taper down in dosage for a period of time following the adult heartworm treatment injections.

Post-Treatment Care

During and after the melarsomine treatment, it is highly important to limit exercise during this period to decrease any complications associated with the treatment. The reason is parts of the dead worms may block blood flow through the dog’s pulmonary vessels –causing more inflammation. When a Labrador is working out, the blood flow increases to blocked areas and this can cause the capillaries to rupture, as the heart pumps blood through them, causing difficulties in breathing and even death.

Complete crate rest except for potty walks and minimal activity at home is a must. Your veterinarian can only advise you when your Labrador should resume normal exercises activities.

You should make your dog undergo retesting after six months to ensure that all of the microfilariae, larvae, and adult heartworms are dead. If your Labrador remains heartworm-positive even 6 months after the treatment, he may need to undergo the same treatment again to kill the remaining worms.

When is Surgery Needed?

Not all heartworm cases can be treated solely with medication. In some cases, surgery is the ultimate option. If heartworms are in the caudal vena cava, which is a large vein between the heart and the liver, surgical removal of these worms is necessary.

The good news is drug treatment for heartworm-positive dogs is usually successful – especially if the dog shows only mild signs of the disease.

Preventing Heartworms in Dogs

Preventing heartworms is better and a whole lot easier than cure. There are a number of heartworm preventatives your veterinarian can recommend. There are also combination heartworm preventatives that work great against heartworms, external parasites, and internal parasites.


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