Heartworm disease is preventable, but every year this deadly disease affects many pets. Myths abound about heartworms, and false information may prevent a pet from receiving the protection they need. Learn the truth about heartworm disease with The Neighborhood Vet team, as we debunk common myths about this condition.

Myth: Infected pets transmit heartworms 

Truth: Infected mosquitoes transmit heartworms. When mosquitoes take a blood meal from an infected domestic dog or wild canine, the insect ingests baby heartworms (i.e., microfilariae), which mature to an infective stage while in the mosquito’s body. After two to three weeks, the microfilariae travel to the mosquito’s salivary glands so they can infect a vulnerable pet during the insect’s next blood meal. While the affected mosquito feeds, the microfilariae swim through the bite wound to infect the pet. 

Your pet won’t contract the disease through interaction with a heartworm-positive animal. However, if a heartworm-positive pet lives in your area, your pet’s infection risk increases, because the infected pet provides a nearby reservoir for the parasites.

New York state has a lower incidence, but dogs rescued from the South are often infected, which increases the risk to our pets. 

Myth: Heartworms only affect dogs

Truth: Heartworms cause significant health issues for dogs and cats. However the disease course is different in the two species:

  • Dogs — Dogs and wild canines, including foxes, coyotes, and raccoons, are natural heartworm hosts, and while parasitizing these animals, heartworms mature, mate, and produce offspring. When the young heartworms enter your dog, they travel to their heart’s vasculature. These parasites cause inflammation that leads to vessel narrowing, which inhibits the heart’s ability to pump blood throughout the body effectively, and eventually causing congestive heart failure (CHF). In addition, because numerous worms can accumulate in a dog’s heart, they can block blood flow through the heart, causing caval syndrome, a life-threatening condition.
  • Cats — Cats are atypical heartworm hosts because they don’t provide a welcoming environment for the parasites. When young heartworms enter a cat, the feline immune system clears most of the parasites, preventing them from growing to adulthood. However, if the immature heartworms reach a cat’s lung vasculature, they trigger a massive immune response, leading to heartworm-associated respiratory disease (HARD). This condition can cause extensive, irreversible lung damage. In addition, a cat’s small size means that if one or two heartworms reach adulthood, they can block the tiny feline heart’s blood flow.

Myth: Heartworms only affect pets who live in the southern states

Truth: According to the Companion Animal Parasite Council (CAPC), heartworms have been reported in all 50 states, and heartworm prevalence is increasing along the Atlantic coast, pressing into the northeastern states. Mosquitoes’ population and species diversity, combined with the region’s population density, suggests that heartworm infections are likely to affect the health of many pets who live in the area.

Myth: Heartworms affect pets during the summer only

Truth: Mosquitoes thrive in hot, humid weather, but climate change has led to an unpredictable peak mosquito season. Mosquitoes are active at temperatures higher than 40 degrees. While many people believe the first frost is a reliable indicator signaling mosquito season’s end, hibernating mosquitoes may emerge during a warm snap and target your pet for a meal. Therefore, you must ensure your pet receives a year-round heartworm preventive product to protect them from these dangerous parasites.

Myth: Heartworms only affect pets allowed outdoors

Truth: Pets allowed outdoors have a high heartworm disease risk, but mosquitoes are sneaky insects that easily enter your home through open windows, doors, vents, and torn screens. In addition, if your indoor pet enjoys time on a protected patio or balcony, an infected mosquito can bite your four-legged friend.

Myth: I would know if my pet had heartworms

Truth: Heartworm-positive pets rarely exhibit signs in the initial disease stages, and in some cases, the first sign is sudden death. Usually, a pet’s condition is quite advanced by the time they exhibit signs, making treatment extremely difficult. A pet’s heartworm disease signs include:

  • Dogs — Heartworm signs include lethargy, weight loss, increased respiration rate, a soft cough, and exercise intolerance. When a dog’s condition progresses to CHF, they may have fluid accumulation in their abdomen, resulting in a pot-bellied appearance.
  • Cats — Heartworm signs typically mimic feline asthma, manifesting as open-mouthed breathing, increased respiration rate and effort, vomiting, collapse, and sudden death.

Myth: I can simply have my pet treated if they contract heartworm disease

Truth: No medication is approved to treat heartworms in cats, making prevention the only way to protect your feline friend. Dogs’ treatment is risky, and to kill the parasites at every life stage, you need to follow these strategies, which include:

  • Restricting activity — Physical exertion can exacerbate an infected dog’s already-damaged heart and lungs. During heartworm treatment, you must confine your dog, restricting their activity level.
  • Killing microfilariae — Our team prescribes medication to kill the baby heartworms.
  • Administering antibiotics — Heartworms are associated with the bacterial infection Wolbachia, which intensifies the inflammatory response. To address a dog’s infection, we prescribe appropriate antibiotics.
  • Decreasing inflammation — Steroids may be necessary to reduce a dog’s inflammatory response.
  • Killing adult heartworms — To kill adult heartworms, we must administer medicine through painful injections into a dog’s lumbar (i.e., lower back) muscles. 
  • Monitoring your pet — Side effects such as blood clots and anaphylaxis are possible, and you must monitor your dog closely throughout treatment.

Protecting your pet from heartworm disease is easy through the administration of a year-round heartworm prevention product. Schedule your dog’s heartworm test with The Neighborhood Vet team, and we will also recommend the most effective parasite preventive product for your furry pal.