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What Are the Symptoms of Heartworms & How to Protect Your Pet

heartworm prevention

What Is Heartworm Disease?

Heartworm disease is a very serious disease found in ferrets, cats, and most commonly dogs. If untreated, it can result in severe lung disease, heart failure, organ damage, and in some cases it may be fatal.

Heartworm disease is caused by a parasite called Dirofilaria immitis, which spreads through a mosquito’s bite. The mosquito serves as the intermediate host, meaning the worms live inside the mosquito only for a short period while becoming infective and able to transmit heartworm disease. The next time this mosquito bites an animal, it will transfer the larvae into its bloodstream. The animal will then serve as the definitive host, which means the worms mature into adults, mate, and even produce offspring while living inside the animal. 

These worms often nestle into the heart, lungs, and associated blood vessels of the infected animal, hence the name “heartworm” disease.

  • Mature heartworms can live for up to 5 to 7 years in dogs and 2 or 3 years in cats.
  • Every mosquito season puts animals at increased risk for developing the disease or growing numbers of worms in already infected animals.

What Are the Symptoms of Heartworms in Dogs?

In the early stages, many dogs will show only few symptoms (if any at all) and the severity depends on several things: 1) how many worms are residing inside of the dog (worm burden), 2) how long it has been infected, and 3) how its body is responding to the presence of the worms. The dog’s activity levels also play a role in the severity of heartworm disease and when the symptoms are first noticed. 

Inactive dogs, recently infected dogs, or those that have low worm burdens may not show obvious signs, whereas dogs with heavier worm burdens, active dogs, or those that have been infected for a long time will often show more obvious symptoms.

Some signs of heartworm disease can include:

  • Mild, persistent cough
  • Lethargy/avoids exertion
  • Fatigue after mild to moderate activity
  • Difficulty breathing
  • Periodic vomiting
  • Decreased appetite
  • Weight loss

As the disease progresses, pets may develop heart failure and/or a swollen tummy as excess fluid builds up in the abdomen. Dogs can also develop sudden blockages of blood flow in the heart, leading to cardiovascular collapse. This is marked by the sudden onset of labored breathing, pale gums, and dark, bloody or coffee-colored urine usually requiring prompt surgical intervention.

What Are the Symptoms of Heartworms in Cats?

While most heartworms do not survive to the adult stage in cats, it is possible. Both outdoor and indoor cats are at risk, and the signs can be either very subtle or very dramatic. 

Some symptoms displayed by infected cats may include:

  • Coughing or asthma-like attacks
  • Lethargy
  • Periodic vomiting
  • Lack of appetite
  • Weight loss

Occasionally, an infected cat may have difficulty walking, experience seizures or fainting, or suffer from fluid build-up in the abdomen similar to that in dogs.

How to Prevent Heartworms in Your Pets

The best treatment is prevention, and fortunately, there are many FDA-approved preventative products available today. However, all of them require a veterinarian’s prescription so scheduling an appointment is the first step toward preventing heartworm disease. 

The most common products are given on a monthly basis either orally or as a topical liquid applied to the skin by the pet owner. Another option is an injectable product, administered just under the skin every 6 or 12 months by a veterinarian. Additionally, some preventative medications also contain effective ingredients against certain intestinal parasites (hookworms and roundworms).

Year-round prevention is the best option to help ensure the safety of your pet. Contact us at AZPetVet to schedule a preventative care exam and we can help you decide which options are best suited for your pet!

Disclaimer: Not intended to be a substitute for professional veterinarian advice, diagnosis, or treatment. Always seek the advice of your veterinarian with any questions you may have regarding the medical condition of your pet. If you think your pet has a medical emergency, call or visit your veterinarian or your local veterinary emergency hospital immediately.

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