Warmer days and more time outdoors herald the beginning of spring, and most of us are excited about the longer days and more opportunities to hike, run, and play outside with our pets. But, along with the warmer temperatures, come many detested bugs, including mosquitoes. 

Mosquito bites are uncomfortable and annoying to us, but are much more dangerous for our pets, because they cause potentially life-threatening heartworm disease. The disease is more prevalent in subtropical climates but now is found in pets and wildlife in all 50 U.S. states and Canada. About one in every 100 dogs tested is heartworm-positive, according to the Companion Animal Parasite Council.

Fortunately, this deadly disease is entirely preventable, which makes education critical. The  Bayview Animal Hospital team categorizes heartworm disease in the top five diseases every pet owner should be familiar with, so we are providing all the information you need about heartworm disease and prevention. 

What is heartworm disease? 

Heartworm disease is caused by a roundworm parasite, Dirofilaria immitis, that infects dogs and wildlife through a mosquito bite. Cats are also affected, but less commonly. An infected mosquito transmits the heartworm larvae (i.e., microfilariae) to your pet, and the larvae mature over several months—they can reach a foot in length—make their home in the animal’s lung and heart tissue, and reproduce.

Signs include coughing, lethargy, exercise intolerance, weakness, collapse, and in severe cases, sudden death. The worms can cause lifelong tissue damage, despite mild symptoms and, left untreated, pets become disease carriers if they are bitten by a mosquito that then bites an uninfected pet. 

Veterinarians can usually diagnose heartworm disease early, before the pet shows any signs, with a simple blood test. The American Heartworm Society recommends the heartworm antigen test, which is specific for adult female heartworms and can detect antigens in the blood when the pet has three or fewer adult females in their heart. Another option is a test to detect microfilariae in the blood. X-ray or ultrasound imaging can show heart and pulmonary artery swelling that can be caused by the adult heartworms. One dog can harbor up to 100 worms.

Treating heartworm disease in dogs

Heartworm treatment is complicated and can be dangerous for your dog. They will require medication by injection over several months to kill the adult heartworms. Unfortunately, the injections are extremely painful, plus the pet must be strictly confined to a cage and closely monitored for several months, because as the adult worms die, fragments will clot, obstruct the pulmonary artery, and compromise blood and oxygen flow to the heart and lungs. Many pets need to be hospitalized, depending on their worm load and the stress on their heart, lungs, and other vital organs. Treatment is not only painful for the dog, but also expensive for the owner.

Heartworm disease and cats

Cats, wrongly, are sometimes an afterthought regarding heartworm disease. Cats are dead-end hosts for heartworms, meaning the worms cannot reproduce, but only a few worms reaching adulthood can wreak havoc on your cat’s health. Worse, immature heartworms can cause heartworm-associated respiratory disease (HARD), a severe inflammatory condition in cats, and the first sign of disease is often sudden death. Sadly, no heartworm treatment is available for cats, making prevention crucial.

A better option: Heartworm disease prevention for pets

It’s a no-brainercompared with heartworm treatment, prevention is straightforward, safer, and more cost-effective for dogs. Preventives come in several forms, including monthly chewables and topical applications, or six-monthly injectables, and your veterinarian will prescribe the best treatment for your pet based on their age, lifestyle, and general health status. 

Heartworm preventives work by killing the infective heartworm larvae before they mature into adult heartworms, which are resistant to regular treatment. Treatment can protect your pet with 98% efficacy, but you must be consistent with administration and the appropriate dosage. Fortunately, setting up a reminder system has never been easier. 

In addition to regular preventives, you can protect your pet against heartworm disease by: 

  • Keeping your pet indoors during peak mosquito season Mosquitoes are most active in the evenings in the subtropical states, including Florida, during the warmer months, so keep your pet indoors at peak mosquito times. 
  • Use mosquito repellent —If your pet must be outside, a pet-safe mosquito repellent spray or lotion can help. 
  • Schedule regular checkups and heartworm testing Regular testing by your veterinarian can help catch heartworm disease early and prevent long-term damage  and the need for treatment. 

At Bayview Animal Hospital, we are committed to your pet’s quality of life and well-being, which includes heartworm prevention. Contact us if you have any questions or concerns about this serious problem.