While you may have heard about heartworm disease, especially at your pet’s annual wellness visit with your Medina Veterinary Clinic veterinarian, you may not know all the illness’ finer details. To underscore the seriousness of heartworm disease, our team has compiled some of the most important facts every pet owner needs to know. 

#1: Heartworm disease is transmitted by mosquitoes

Unlike many other diseases in your pet, heartworm disease is not directly transmitted from pet-to-pet. Instead, it’s transmitted through the bite of an infected mosquito. If a mosquito carrying heartworm larvae bites your pet, the larvae can be injected into your furry pal’s bloodstream. So, while a heartworm-positive pet in your neighborhood cannot give your pet heartworm disease, they can serve as an infection reservoir.

#2: Heartworm disease can affect any mammal

The heartworm’s preferred host is a dog or wild canine, but they can infect any mammal, including cats, ferrets, horses, seals, and people. Although your cat is not the ideal host for heartworms, they can still develop serious, sometimes fatal, disease from infection. To keep all your pets safe, including your indoor-only house cat, ensure they receive year-round heartworm prevention.

#3: Heartworms can be difficult to detect until the disease is advanced

Unlike other “worms,” heartworms require a blood test, rather than a fecal test, for diagnosis. Additionally, heartworms have a longer life cycle than intestinal parasites, making the test’s timing critical for an accurate diagnosis. We recommend testing your pet annually for heartworm disease for several reasons:

  • Maturation — Heartworms require six months to reach adulthood after your pet has been bitten by an infected mosquito.
  • Testing — Heartworm tests detect only adult female heartworms, so immature and male worms can create a false-negative result.
  • Disease progression — Heartworm disease signs often do not appear until the disease is advanced.
  • Prevention failure — Pets can spit out, vomit, or rub off their heartworm preventive, or a dose can be missed, allowing infection to develop.

Without regular annual testing, you may not realize your pet has heartworm disease until it’s advanced enough to cause serious illness, making treating your furry pal much more difficult.

#4: Heartworm disease is not solely a summertime condition

Mosquitoes are hardy pests that can survive harsh winters in your garage or home. When temperatures drop, these insects may move indoors and can infect your pet any time of year. Additionally, mosquitoes can pop back up if the temperature rises above freezing in the winter. With unpredictable Ohio weather patterns, a single “warm” day in January can allow mosquitoes to emerge from their hiding spots and infect your pet with heartworms.

#5: Heartworm disease signs appear differently in cats and dogs

Since dogs are the preferred host for heartworms, the disease process follows a typical pattern. First, you’ll notice a mild cough and some fatigue after moderate activity. As the disease advances, the dry, hacking cough will worsen, and your dog will become more intolerant of any activity. In late disease stages, your dog may develop congestive heart failure and display a rounded abdomen filled with fluid.

In cats, signs can vary. Heartworms rarely reach adulthood in cats, who are not ideal hosts, and whose immune system works hard to eradicate the foreign parasites. However, immature heartworms can create asthma-like respiratory signs, such as wheezing, coughing, and difficulty breathing, as well as other signs that can include vomiting, diarrhea, difficulty walking, collapse, or sudden death.

#6: Heartworm treatment is much harsher than prevention on your pet

When you give your pet a heartworm preventive, the product works to kill the immature heartworm stages before they reach adulthood. By killing off the small, young heartworms before they reach full-size—as much as a foot in length—your pet experiences minimal, if any, side effects. However, once heartworms are fully grown, treating your dog is much more difficult. To eradicate adult heartworms, an arsenic compound is injected deep into your dog’s lumbar muscles, with two or three injections spaced a month apart possibly required. Your dog must be exercise-restricted throughout the entire process, so they may not be able to run and play for months while they’re undergoing heartworm treatment.  

#7: Heartworm disease in cats has no treatment

Unfortunately, no heartworm treatment is approved for cats. Supportive care can help manage any signs, but sudden death is always a possibility. Therefore, prevention is more critical for cats, since there is no treatment.

Don’t let an infected mosquito slip past your pet’s fur. Protect your pet with year-round heartworm prevention. Contact our Medina Veterinary Clinic team for the best heartworm preventive options for your furry pal.