Heartworm Prevention 101

Heartworm disease is spread by mosquitoes, and it is said that both temperature and humidity contribute to the life cycle of heartworms. It is mostly considered as a disease that only affects dogs, but it can also affect other mammals.

In dogs, heartworms can fully mature into adults, mate, and produce offspring. The worms can cause permanent damage, which might affect the dog’s health even after the parasites are removed.

Cats can be infected, but the heartworms will rarely survive into adulthood, and thus, they can’t reproduce. This doesn’t mean that the heartworms do not cause any damage to cats because even the developing worms can cause damages. Cats most times go undiagnosed because they show very little to no symptoms as dogs do. The medication that treats dogs cannot be used in cats, and therefore, cats suffer from a disease called Heartworm Associated Respiratory(HARD).

The Life Cycle of a Heartworm

If a mosquito bites a dog, it will ingest the maggot stage of heartworm (microfilaria). The microfilaria will mature into a larva inside the mosquito then will inject the L3 larval stage back to the dogs, and they will infect them with heartworms.

Once the dog has been infected, the worms can live for like five to seven years if they won’t be treated. That’s why you should give your dog heartworm prevention every month.

Signs and Symptoms of a Heartworm Disease

At the early stages of the disease, dogs may show signs such as:

  • Fatigue
  • Loss of appetite
  • Mild Cough
  • Weight loss
  • Uninterested in playing or exercise

As the disease progresses the signs and symptoms may include:

  • A swollen belly
  • Difficulty in breathing
  • Pale gums
  • Blood in the urine
  • Heart failure
  • Kidney disease

Effective Ways to Protect Your Pet From Heartworms

1. Take prevention measures

Heartworm is 100% preventable, and there are several safe and effective preventive medications for heartworms. Understand the risk involved, for example, the heartworms can affect the heart, kidney, liver, or lungs.

Apart from the prevention measures, in case your dog is infested with heartworms, you should understand the treatment options. If discovered early enough, it can be treated without permanent damage to the heart or lungs. Treatment can be very costly sometimes, and so, prevention is the best method.

2. Eradicate Flea Problems

If your pet happens to be attacked by fleas, he may suffer excess scratching, which may result in skin damage or hair loss or may suck so much blood causing anemia. These parasites can be found in your home, and that’s why it’s important to declutter your house whether you stay in an apartment, a tiny house, or a container home. Ensure that your house is well organized to avoid the fleas from taking residence in your home because this may also be disturbing to humans.

Flea infestations are very difficult to eradicate. If you see a flea on your pet, it is most likely that there are hundreds more on the pet or around the pet’s environment. To effectively conquer the eradication of these parasites, treat all your pets even if they do not show any signs of infestations. It’s also important to do checkups for your pets every year.

Testing & Treatment

The American Heartworm Society (AHS) recommends that dogs should be treated with heartworm prevention, and all puppies should be introduced to heartworm prevention as early as possible, which should not be later than 8 weeks old. The AHS also recommends that all dogs and puppies should be tested for infection at least once a year.

During testing, your veterinarian will test for heartworms by doing an antigen test. This will involve testing a blood sample, and if the test comes back positive, then a second test should be done. This is to confirm that the diagnosis is correct because the treatment is expensive and complex. Heartworm infection is a serious and progressive disease. The earlier it is detected, the higher the chance of the dog surviving and the lower the chance of causing permanent damage to either their lungs or heart.

Frequently Asked Questions

Is Heartworm Disease Considered Contagious?

Heartworm is not directly contagious since a dog cannot spread it to another dog directly. There is a need for a mosquito for transmission. Having an infected dog may be a risk since many mosquitoes may end up being infected, and they may transmit the disease to another dog.

What Should I Do if I Miss a Dose?

If you miss a single dose of prevention or treatment, it could lead to heartworms, although the test may show negative since it takes 6 to 7 months for the test to show positive due to its life cycle. It is recommended that if you notice you have missed a dose, start it and get your dog tested after one year to ensure your dog is safe.

Why is it Necessary to Give Prevention for 12 Months?

This is because of two main reasons:

  • A single dose does not kill 100%, but repeated doses do kill 100%
  • Monthly prevention is important since it also prevents intestinal parasites from spreading to humans

How Does Heartworm Prevention Protect My Dog?

When a dog is given heartworm prevention, the dose acts as a dewormer because it kills the possible larva stages. The medication doesn’t stay in the dog’s system for 30 days because it’s always in and out within 24 hours. Note that this prevention is proved not to kill adult heartworms because it kills only the worms in the development stages.

How Often Should I Get My Pet Tested?

It is recommended that pets which are on the preventive medication should be tested every year and those that are not should be tested after 4-6 months because of the life cycle of heartworm.


Depending on your pet’s lifestyle, size, or activity, prevention will always be the best medicine to avoid high treatment costs. The best step is to ask your veterinarian to prescribe a dose for your dog that will help prevent heartworm disease.

Heartworm Pet Solutions

WITNESS HW Heartworm Canine/Feline Antigen Test Kit  (10 tests)

WITNESS HW Heartworm Canine/Feline Test Kit

Panacur C Canine Dewormer


BeneBac Plus Pet Powder

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