Heartworm Prevention

Heartworm prevention is an essential concern for every pet owner and veterinarian. The disease is severe and highly damaging to your pet’s body if they get it, so prevention is a much better option than trying to treat it after the fact.

We will cover what heartworm is, how it spreads, and what the best ways are for you to prevent your pet from getting it.

What is Heartworm?

Heartworm is a disease caused by worms living in the heart of an animal. Mosquitoes transmit heartworm disease to your pet. Heartworm is a potentially fatal disease that can cause heart failure, lung disease, and other organ failures.

Heartworm disease has been diagnosed in all 50 states, meaning that this problem exists regardless of where you live. Here in Colorado, heartworm disease was very rare at one time, but its incidence has increased in recent years.

Once your pet is infected, worms begin to grow inside of your pet’s body and can inhabit their heart, lungs, and various blood vessels.

How Heartworm Spreads

Diagram showing cycle of Heartworm infection

As mentioned earlier, the mosquito plays an essential role in the heartworm life cycle. Adult female heartworms living in an infected dog, fox, coyote, or wolf produce microscopic baby worms called microfilaria that circulate in the bloodstream.

When a mosquito bites and takes a blood meal from an infected animal, it picks up these baby worms, which develop and mature into “infective stage” larvae over 10-14 days. Then, when the infected mosquito bites another dog, cat, or susceptible wild animal, the infective larvae are deposited onto the surface of the animal’s skin and enter the new host through the mosquito’s bite wound.

Once inside a new host, it takes approximately 6 months for the larvae to mature into adult heartworms. Once mature, heartworms can live for 5-7 years in dogs and 2-3 years in cats. Because of the longevity of these worms, each mosquito season can lead to an increasing number of worms in an infected pet.

Symptoms of Heartworm

It is more common for dogs to get heartworm, but cats can get it too. A pet can have heartworm without initially showing symptoms. The signs of heartworm disease depend on the number of adult worms present, the location of the worms, the length of time the worms have been in the pet, and the degree of damage that the heart, lungs, liver, and kidneys have suffered. But here are symptoms to watch out for:

  • Occasional or persistent coughing: As the heartworm progressively gets worse, your pet’s cough will become more frequent. But you shouldn’t ignore even a mild a mild cough that is persistent.
  • Trouble breathing: As the disease progresses, breathing may become more and more labored.
  • Tiring quickly: With blood flow being blocked or at least partially blocked, your pet will tire much more rapidly, so be sure to bring them in even if you’re not sure what’s wrong.

Treatment of Heartworm

Another reason preventing heartworms is so important is that the treatment for a heartworm infestation is unpleasant and comes with significant risks for your pet. However, we can successfully treat most infected pets. After stabilizing your pet’s condition, treatment then takes place over several steps. Your pet may need to stay at our clinic for observation. Heartworms must be destroyed gradually. Destroying them too quickly can be dangerous for your pet. Due to the length and complexity of treatment, treatment can become expensive.

How to Prevent Heartworm

Now that you understand what heartworm disease is and how it spreads, here is what you can do to help keep your pet safe and healthy.

Routine veterinarian visits: Schedule your pet for their annual checkup with us. Performing regular heartworm testing is included in this checkup and is the first defense for keeping your pet safe.

Preventative medication: There are various preventative products that you can use on your dog to ward off mosquitoes and prevent heartworm. You can administer these products orally or topically, and prevention is far more effective and less costly than treatment if your pet is diagnosed with heartworm. These medications are available only by prescription, and we can answer any questions you might have about how to administer them when you come to pick them up.

Keep your home mosquito-free: Mosquitoes can also be a threat in and around your own home. Mosquitoes can breed in small amounts of stagnant water. Check out flowerpots, empty containers left outside (buckets, toys), rain gutters, and low-lying areas in the yard. Do your best to remove any stagnant water around your house to minimize their numbers.

Outdoor bug control: Minimizing bugs in your yard is very important in helping to keep bugs away from your pet. You may want to consider using insecticide spray for your yard. Be sure to choose a pet-friendly product and properly follow the manufacturer’s instructions.


We cannot overstress the importance of heartworm prevention. The disease can go on for years without being detected before it damages the heart and other vital organs. Additionally, the disease is unpleasant and comes with significant risks for your pet, although we can treat most infected pets successfully. But clearly, the best way to protect your pet from heartworm is with preventative medicine and routine veterinarian visits.

With your help, we can protect your pet from heartworm and do our part to reduce the incidence of heartworm disease in Colorado again. We are more than happy to answer any questions, big or small, that you have about heartworm or any other concerns you have about your pet.

Amigo Animal Clinic
Grand Junction, Colorado

What's Next

  • 1

    Call us or schedule an appointment online.

  • 2

    Meet with a doctor for an initial exam.

  • 3

    Put a plan together for your pet.