Everything You Need to Know About Heartworm

A sad dog leaning against the couch.

When it comes to promoting and protecting pet health, minimizing vulnerability to parasites is a huge deal. In addition to stopping the problems caused by fleas, ticks, and other external parasites, year-long parasite prevention medication reduces the risks associated with heartworm disease. Spread by mosquitoes, heartworm disease can be deadly. 

Since April is Heartworm Awareness Month, we wanted to take the opportunity to share some tips about avoiding heartworm: 

Breaking It Down

Mosquitos carry the parasitic worm, Dirofilaria immitis, known to cause heartworm disease in certain hosts. Dogs are ideal hosts for adult heartworms to grow, and spawn offspring called microfilariae. 

Capable of spreading through their host’s bloodstream, microfilariae can get sucked into the mouth of another feeding mosquito where they spend 2 weeks developing into larvae. The cycle continues when the infected mosquito deposits the larvae into another host. Over the next 6-7 months, larvae will mature into adult heartworms. 

The Dangers of Heartworms

Left alone, heartworms can grow up to 12 inches long. Closely resembling spaghetti noodles, heartworms take up space in the heart, lungs, and blood vessels where they cause heart failure, organ damage, and lung disease. Without interruption or intervention, heartworms can live (continually reproducing) between 5-7 years in dogs and 2-4 years in cats.  

Cats are not considered natural hosts for heartworms, making it difficult for heartworms to mature and reproduce. This means the average number of heartworms is much lower in cats (1-2 worms) than dogs (15-over 100). 

Symptoms, Diagnosis and Treatment

Few clinical symptoms may be noticeable in the early stages of heartworm disease. As the worms mature and multiply, the following symptoms may be seen:

  • Fatigue
  • Coughing that slowly worsen
  • Breathing difficulty
  • Appetite and weight loss
  • Vomiting

Blood tests and X-rays can confirm the diagnosis of heartworm disease. Treating heartworm disease in dogs is possible with injectable medication, but it can be very taxing on a pet dog’s body. There is no known treatment for cats, although surgical removal of worms can improve symptoms. 

The Meaning of Prevention

To avoid the risks, cost, and difficulty associated with treatment, the best practice is to establish and maintain year-long parasite prevention tactics. 

Annual heartworm screening is required prior to administering heartworm preventive medication (due to the risk of shock), and may even lead to early treatment if necessary. 

Even a single missed dose can result in an infection. Heartworm screenings can only detect worms that are a minimum of 7 months old. Because of this, pets should be screened as early as 6 months old, and then every year afterwards. 

Parasite Prevention For the Win

This April, our staff invites pet owners to check their pet’s heartworm disease strategy. If it’s been awhile since their last screening or they missed a dose earlier this year, we encourage you to schedule an appointment. We are always here to support your pet’s wellness, and look forward to speaking with you at (916) 737-5670.