Symptoms of Heartworm in Dogs in Matthews, NC

Heartworm disease is a serious and potentially deadly disease that can affect dogs, cats, and ferrets, as well as wild canine species, and in the US, cases of heartworm disease have been reported in all 50 states, as well as in other parts of the world. Although testing and prevention are readily available from your veterinarian in Matthews, NC, there are several symptoms of heartworm in dogs that owners should know.

Symptoms of heartworm in dogs in Matthews, NC

But first, we will look at what heartworm disease is, and how it can harm, and be potentially deadly for your best friend.

What is Heartworm Disease for Dogs in Matthews, NC?

Heartworm disease is caused by parasitic worms called heartworms. The reason that they’re called heartworms is that they live in the heart, more specifically the pulmonary valve of the heart. These worms can also infiltrate other parts of the heart and lungs, and if untreated, can cause severe lung disease, a blockage of the valves of the heart, and damage other vital organs in the body. Adult heartworms are about the size of cooked spaghetti noodles so imagine these “noodles” filling up a chamber of the heart and blocking the blood flow to the body.

In severely affected dogs, you may see a swollen abdomen due to fluid buildup because the heart cannot effectively circulate blood, a cough, or other signs such as respiratory distress. Heartworm disease in dogs is known as a silent killer because it can take months before your dog shows symptoms.

How Do Dogs Develop Symptoms of Heartworm in Matthews, NC?

Heartworms are transmitted by mosquitos, which act as vectors and play an important part in the transmission of heartworms to your dog. Adult female heartworms create infant worms called microfilaria that circulate in the bloodstream of the body. When a mosquito bites a dog that has heartworm disease and takes a blood meal, the mosquito ingests the baby worms, which develop and mature into the “infective stage” of larvae in 10 to 14 days.

When the infected mosquito, the vector, bites another dog, cat, or other animals, the infective larvae are injected into the new host through the mosquito’s bite. Once inside the new host, it takes about six months for the larvae to mature into adult heartworms. Once mature, heartworms can live for five to seven years in dogs, and up to two or three years in cats.

Heartworms can live a long time in your pet, and it is important to note that with each new mosquito season, more heartworm larvae can be transmitted to your dog. When veterinarians diagnose heartworm disease, a blood test is run, and this test can detect heartworm antibodies in the blood. A blood smear can also show microfilaria moving in the blood sample on a slide.

In the early stages of the disease, dogs may not show any symptoms of heartworms at all, but the longer the dog goes without diagnosis or treatment, the more likely symptoms will develop. Young dogs, or dogs that are normally active or those with health issues may show more obvious signs than other dogs.

If you are a dog owner, you have probably discussed parasite prevention with your veterinarian in Matthews, and know that your dog should be on medication. Heartworm medications can either be a once-a-month chewable tablet, or an injectable form that can last up to 12 months. You and your veterinarian can decide which medication is best for you and your dog.

If your dog is diagnosed with heartworm disease, early treatment is essential and can improve your dog’s chances of recovery.  However, as a pet owner, it is still important to recognize the signs and symptoms of heartworms in dogs.

Symptoms of Heartworm in Dogs in Matthews, NC

According to the FDA, there are four stages, or classes, of the disease and symptoms of heartworms in dogs appear differently in each stage.

Class 1 Symptoms

In this class, there may be no symptoms, mild symptoms, or a light, dry cough.

When heartworms infiltrate the lungs and start reproducing in the lungs and the surrounding vessels, your dog may start to cough, usually a dry, unproductive cough that can be more obvious after exercise.  Sometimes dogs may have “coughing fits,” which may cause fainting.

Class 2 Symptoms

In this class of heartworm disease, there are a couple different symptoms of that can begin to appear in your dog.


One of the first signs of heartworm disease in dogs is lethargy, or acting tired and “lazy.” If your dog doesn’t want to run, or hike or be as physically active as he usually is, contact your veterinarian in Matthews for a pet exam.

Dogs with heartworm disease often feel weaker, and low-energy because the worms are putting an extra load on the heart and lungs, and that can affect energy levels and the movement of oxygen throughout the body.

Weight Loss or No Appetite

As heartworm disease advances, your dog may not feel like eating as much, and you may notice some weight loss. If you notice these signs, make an appointment with your local veterinarian as soon as you can to rule out heartworm disease or other illnesses.

Class 3 Symptoms

In this more advanced class of the disease, the symptoms of heartworms in dogs start to become more dangerous.

Panting and/or Shallow Breathing

As heartworms spread through the heart and lungs, your dog will have a harder time moving blood and oxygen around his body.

Also, as the heartworms block vessels, the areas around these vessels will see the fluid build-up, making it even harder for your dog to breathe and get oxygen. This will cause him to take more shallow, rapid breaths.

Distended Abdomen and/or Chest

In advanced cases, dogs with heartworms may exhibit a swollen abdomen, or distended chest, which is caused by the heartworms backing up the vessels of the heart and lungs, causing a sort of “dam” effect where fluid collects in the belly and the tissues around the heart and lungs.

Seizures or Blindness

Heartworms can reach other places besides the heart and can migrate to the brain and eyes, causing seizures and blindness. Although these symptoms are rare in heartworm disease, they are still a consideration.

High Blood Pressure

Dogs with heartworm disease can also experience high blood pressure that results from the heart having to work harder to pump blood through vessels that are partially blocked by heartworms.

Class 4 Symptoms

In this particular class of heartworm disease, there are two main symptoms your dog may experience.

Caval Syndrome or Fainting

As heartworms infect the heart, blood flow is blocked, and this is known as “vena cava syndrome.” Known as CS, vena cava syndrome happens when heartworms block the right atrium of the heart, the right ventricle, and the vena cava (the large blood vessel responsible for bringing blood back and forth to the heart).

As a result, the blockage of worms interferes with the functions of the tricuspid valve, reducing blood flow through the right side of the heart, leading to heart failure and cardiovascular collapse. When this happens, a dog will faint to reduced blood flow to the brain and may become shocky.

At this late stage, the disease has progressed so far that the prognosis for survival is very grave.

When Should I Have My Dog Tested for Symptoms of Heartworm in Matthews, NC?

If you have questions about heartworm testing in your dog, contact your veterinarian in Matthews for recommendations.

The American Heartworm Society suggests that dogs be routinely tested for heartworm disease, and make the following recommendations:

  • Puppies under six months can get their first heartworm prevention medication without a heartworm test (because it takes six months for a dog to test positive after being infected).
  • At six months you can have your puppy tested, and each year after that.
  • Adult dogs over the age of six months that haven’t been on heartworm medication before should be tested, then retested six months later, then once a year.

If you’re ever concerned that your pet is experiencing any symptoms of heartworms in dogs, please give us a call or make an appointment. Our veterinarians can do a simple blood draw to check for the presence of heartworms in your dog. If your dog is infected, we can make recommendations and a treatment regimen for your dog, depending on how ill your dog is.