Heartworm infections in dogs and cats are on the rise in the United States, which puts your pet at greater risk. These little critters can cause major damage to your pet’s heart, lungs, and blood vessels, and could also be fatal. Fortunately, LaGrange Veterinary Hospital is well-stocked with preventive options to stop heartworm infections in their tracks. During Heartworm Awareness Month, we want pet owners to understand how heartworm disease works and how heartworm prevention benefits your pet, so we’re answering commonly asked heartworm disease and prevention questions.

Question: What are heartworms?

Answer: Heartworms are parasites that live in the heart and large nearby blood vessels in infected animals. The parasites prefer dogs and other wild canids, but can also infect cats, ferrets, and several other mammal species, but not humans. They can grow up to a foot long and, in dogs, can reproduce and multiply into the hundreds, which can lead to heart and lung damage, heart failure, or death. 

Q: Is my pet at risk for heartworm infection?

A: All pets are at risk for heartworm infection, because the immature worms are transmitted by mosquitoes, which are present in all U.S. states. Risk is highest in the warm, humid, Southern states, but mosquitoes and infected pets can travel, so disease risk is rising in other areas. Mosquitoes also can easily enter homes, so indoor pets are also at risk.

Q: Are heartworms contagious to other pets?

A: Adult heartworms can reproduce in an infected dog and release immature worms, which circulate in the pet’s bloodstream. These worms can be picked up by mosquitoes and transmitted to other nearby pets, but only after a few weeks while they develop inside the mosquito. Living with or near an infected dog greatly increases heartworm transmission risk, but the disease is not directly contagious from pet to pet. Infected cats do not typically have immature worms circulating in their blood, so they are less likely to serve as a disease reservoir.

Q: How do I know if my pet has heartworm?

A: You probably won’t know if your pet is infected with heartworms unless they are tested. The worms mature slowly and may not cause appreciable disease for months or years after the initial infection. Blood testing can detect adult heartworms, and is recommended annually for all dogs, and prior to starting a prevention regimen in dogs and cats. If a dog or cat with suspected disease tests negative, the test can be repeated six months later, but additional blood and imaging tests may be ordered.

Severe or advanced heartworm disease will lead to heart and respiratory dysfunction. The most common signs in dogs include:

  • Cough
  • Exercise intolerance
  • Weight loss
  • Fluid in the chest or abdomen from heart failure
  • Death from a blood vessel blockage

Infected cats often show no signs, but they can die suddenly without warning. Cats with signs most commonly exhibit respiratory issues, but may also show:

  • Asthma-like symptoms
  • Difficulty breathing
  • Weight loss
  • Vomiting
  • Sudden death

Q: If my pet contracts heartworm, can they be treated?

A: Heartworm infections are treatable in dogs, but the process can be painful and expensive. Treatment involves a series of injections and day hospitalizations to kill the adult worms, preventive medications to kill immature worms, antibiotics to neutralize bacteria associated with the adult worms, and steroids to prevent allergic reactions and inflammation from toxins released by the dying worms. Dogs also must be strictly cage-rested for several months, and the treatment can cost upward of $1,000. Dogs with severe or long-standing infections may require surgery that physically removes the worms.

The same medication used to kill adult worms in dogs is not safe for cats. Infected cats can only be monitored closely and offered supportive care, medications to address their symptoms, and preventive medications to keep new worms from joining the party. Because heartworm in cats can cause serious problems, prevention is crucial.

Q: How does heartworm prevention work?

A: Heartworm prevention comes in topical and oral forms to suit your pet’s needs, and is usually also effective against several intestinal parasites. Doses given monthly work retroactively to kill the immature worms that mosquitoes transmitted in the previous weeks. Our team and the American Heartworm Society recommend providing all pets with heartworm prevention year-round, because skipping only one or two doses can leave them vulnerable to infection.

Q: Is heartworm prevention worth it?

A: Yes! Heartworm prevention is the only way to keep cats safe from the disease’s devastating effects and to ensure dogs do not have to endure painful treatments. Financially, heartworm preventives cost around only $10 per month, but treatment for a dog can cost more than $1,000. 

Invest in heartworm prevention now to avoid expensive and potentially deadly infection and disease later. Ask the LaGrange Veterinary Hospital team about the best heartworm products for your pet, and how to begin a prevention regimen. Contact us to schedule a wellness visit or heartworm test, or if you have other questions about heartworm disease.