Content Reviewed by an Essentials PetCare Veterinarian

Whether you have a new puppy or have had your dog for years, frequent heartworm tests are an important part of your pet’s preventive care plan. Your pet can be screened for heartworms with a simple blood test. 

But what else do you need to know about the heartworm test for dogs? Let’s take a look at what heartworm tests are and why they are so important.

Heartworm Test Basics

You may have heard that you only need to test and treat outdoor pets for heartworms, but this is a myth! All dogs are at risk of heartworms, which is why it’s so important to test regularly and use a monthly preventative. 

There are two types of heartworm tests available:

  • Antigen tests: these tests can detect the presence of heartworm proteins in the blood 6.5-7 months after infection. This is the primary test used to detect adult heartworms.
  • Microfilariae tests: These tests detect the presence of larval, or immature, forms of heartworms that circulate in the bloodstream. They are used with an antigen test to confirm a positive infection. They can also be used for regular screening, but should never be used as the sole form of testing. False negative results can frequently occur if not interpreted with an antigen test.

The heartworm test blood draw can be done in a few minutes. And most antigen test results are available within 10 minutes. So a plan of care can be quickly made if your pet tests positive or you need paperwork for your dog kennel. 

Heartworm Tests at Essentials PetCare

At Essentials PetCare, our experienced technicians can administer a heartworm test for just $30. It is offered as a singular service, or as part of our bundled canine value packages, which start at just $100.

Remember to bring records showing the last heartworm test performed, any heartworm preventative purchases in the past year, and proof of your pet’s current rabies vaccine with the following info:

  • date given
  • date due
  • vaccine manufacturer
  • serial number 

We can give a rabies vaccine at the same time as other services if your pet isn’t up-to-date. 

It’s important to know that with all negative heartworm tests, Essentials PetCare will generate a portable prescription for heartworm prevention. 

So, What Are Heartworms? 

Heartworms are long, thin parasitic worms that can grow up to 12 inches! Heartworms can infect the pulmonary arteries and the right ventricle of your pet’s heart. They are spread through mosquito bites and then develop from larvae in the bloodstream into mature heartworms over a period of about six months.

Once the heartworm larvae have matured in an animal, they will begin producing certain proteins (antigens). At this point, a heartworm test can be positive. While heartworms are only spread through mosquitoes and aren’t contagious, the consequences for an infected animal can be fatal. Plus, any heartworm positive dog can act as a sentinel for mosquitoes to bite and transit the heartworms to other dogs in the same area/neighborhood.

Many infected animals will not present symptoms until the disease progresses over a period of time. This is why regular testing is so important to catch dogs that are positive but aren’t showing any clinic signs. If you notice any of the following symptoms in your pet, you should reach out to your veterinarian and have a test performed.

Symptoms of Heartworm Infection

  • Mild persistent cough
  • Fatigue and unwillingness to exercise
  • Weight loss
  • Decreased appetite
  • Swollen belly 

In certain severe cases of heartworm disease, an animal can experience severe lung damage and/or caval syndrome. This type of heartworm disease causes dark (port-wine colored) urine, pale gums, labored breathing, acute right-sided heart failure, and often rapidly leads to death. Surgery is the only option for treatment at this stage and carries a high risk. Not all animals will survive. 

Why You Should Consider a Heartworm Test for Dogs

Because heartworms can be a silent killer, frequent testing and routine heartworm medicine is the best form of preventative care for your pet. Testing your pet at least annually is a quick and simple way to stay on top of their health. 

Although heartworm prevention medications are incredibly effective, it is rare but possible for your pet to still contract heartworms — especially if you don’t give your pet prevention on a regular schedule.

Also, unless your dog is a puppy, you cannot start a heartworm medication without receiving a negative test result first. This is because heartworm medicine cannot treat an active infection. On the contrary, there can be severe complications if a pet with a pre-existing infection is started on monthly heartworm medicine.

Understanding Your Pet’s Heartworm Test

What happens if your pet tests positive for heartworms? First, remember that there are multiple treatments available, and a positive result does not always mean a fatal diagnosis.

It’s rare, but a heartworm test can result in a false positive. This is why all positive diagnoses should be followed by a confirmation test, as recommended by the American Heartworm Society. This can consist of a microfilariae test or a repeat antigen test. A positive microfilariae test is considered confirmation of an active infection. However, since false negatives can frequently occur with this type of test, a negative microfilariae test should always be followed by a second antigen test for confirmation.

A Positive Diagnosis

If your pet has a positive heartworm test, don’t panic. Take a deep breath and follow these steps:

  • Get a Confirmed Diagnosis. Ensure your dog is truly positive by always having a confirmation test performed.
  • Limit Exercise. Although challenging to do, this can help your dog’s healing process. The more strenuous the exercise, the greater stress on your dog’s heart and lungs during the treatment. Rest is best.
  • Stabilize the Condition. Before you start heartworm therapy, your veterinarian may determine that other treatments may be necessary to stabilize your dog. This can reduce the chances of any complications while undergoing therapy if they are already showing symptoms of infection.
  • Begin Treatment. Once your pet is stable, your veterinarian can determine the best course of treatment for your dog, including the safe initiation of prevention products, based on multiple factors. These include their age, the severity of infection and symptoms, and how long the infection has been present.
  • Test Again. Six months after your dog completes their treatment, you should retest for heartworms. And then be sure to continue with annual testing and a monthly heartworm preventative.

When Should I Test?

Puppies should start heartworm prevention by 8 weeks old. Testing is not necessary at this age, since this isn’t enough time for heartworms to have developed. Because the heartworm life cycle requires about six months from the time of a mosquito bite to the point that adult heartworms are detectable on a test, the first test should be performed after six months of prevention. 

An adult dog with no history of preventative medication should be immediately tested and start on prevention. The dog should then receive a second test in 6 months.  After this second heartworm test, testing should be conducted annually, as long as regular prevention is continued year-round.

It’s also recommended to test for heartworms in six months if your pet has:

  • Missed a dose of medication
  • Recently changed heartworm medications
  • Traveled to an area with high levels of mosquitoes and heartworm disease (twice yearly testing is recommended if you live in one of these areas)

What About My Cat?

Both indoor and outdoor cats are also at risk of contracting heartworm disease. But it is much less common in felines, since the worms do not thrive as well in their bodies. Heartworm testing is not as straightforward in cats as it is in dogs and can require a combination of antigen tests, antibody tests, radiographs (x-rays), and ultrasound to make a diagnosis.

Heartworms take roughly seven to eight months to mature in a cat’s body, and symptoms present differently than in dogs. In most cases, a cat’s immune system will destroy the heartworms before they ever develop into mature worms, but this strong immune response can actually result in severe respiratory disease. This condition is referred to as heartworm-associated respiratory disease, or HARD. Since heartworms are more rare but also potentially more severe, you should notify your veterinarian immediately if you see any of the following symptoms in your cat:

  • Coughing
  • Asthmatic breathing
  • Vomiting
  • Rapid weight loss or loss of appetite
  • Difficulty walking
  • Bloated abdomen from fluid accumulation 
  • Fainting or seizures

Your vet will usually administer an antigen blood test and antibody test, along with an x-ray if they suspect your cat may have heartworms. Since there is no approved heartworm treatment for cats and diagnosis can be difficult, consistent prevention is crucial in cats.

Keeping Your Pets Safe and Healthy

At Essentials PetCare, we know the health of your pet is of utmost importance to you.  This is why we offer heartworm testing as an affordable service to keep your mind at ease and your pet heartworm free! 

Essential Tip: Prevention is the best medicine and routine testing and treatment can save you time and money — and stress for you and your pet! Come in and see us today for a heartworm test.


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