Heartworm disease is often associated with dogs, but cats are at risk, too. Heartworm disease also affects cats differently than dogs, making infections especially difficult to recognize and diagnose.
Heartworms are transmitted through the bite of an infected mosquito. Even cats who spend their entire lives indoors can be exposed since mosquitoes can easily make their way inside. Veterinary organizations recommend year-round heartworm prevention for all cats, regardless of their lifestyle.
Consistent prevention is an important part of protecting your cat’s overall health. Heartworm disease can cause lasting damage to the lungs, and infections can be difficult to detect, making it important to reduce your cat’s risk before heartworms have the opportunity to cause harm.
Heartworm Disease Looks Different in Cats
Cats typically harbor fewer heartworms than dogs, which can make the disease more difficult to detect. Just a single worm can have a serious impact on a cat’s health.
One of the biggest concerns is heartworm-associated respiratory disease, or HARD. HARD can develop when immature heartworms reach the lungs, causing inflammation and potentially permanent changes to lung tissue. Research shows that this damage can begin as early as 70 to 90 days after infection, even when the heartworms never mature into adults.
Heartworm disease can also be challenging to diagnose. Cats typically carry only 1 or 2 worms, therefore testing too early in an infection can produce false-negative results. These diagnostic challenges mean an infected cat may not always test positive right away.
Signs of Heartworm Disease in Cats
Heartworm disease doesn’t always have an obvious set of symptoms. Some cats may show mild or intermittent clinical signs, while others can become seriously ill.
Signs of feline heartworm disease can include:
- Coughing or asthma-like symptoms
- Difficulty breathing
- Vomiting
- Decreased appetite
- Weight loss
- Lethargy
- Fainting or collapse
- Difficulty walking or seizures
- Sudden death
Several of these clinical signs can easily be mistaken for other feline health conditions. Respiratory and gastrointestinal symptoms are particularly important to pay attention to. In a study of more than 91,000 heartworm-tested cats, 7% of heartworm-positive cats initially presented with asthma-like respiratory signs, including coughing and difficulty breathing, while 10% initially presented with vomiting.
Some cats may have a few noticeable warning signs before the disease becomes serious. Research has found that sudden death occurs in up to 20% of cats with adult heartworm infections.
Unexplained coughing, breathing changes, recurring vomiting, or other changes in your cat’s health are always worth discussing with your veterinarian.
More data on feline heartworm disease >>
Indoor Cats Are Also at Risk
It’s easy to assume an indoor-only cat doesn’t need heartworm protection. Mosquitoes don’t need your cat to venture outside to put them at risk.
Heartworm-transmitting mosquitoes can enter homes through doors, windows, screens, and other small openings. Mosquito activity is typically higher during warmer months, but exposure can still occur during colder weather, particularly indoors.
Heartworm exposure may also be more common than many cat owners realize. An estimated 15% to 17% of cats in the U.S. have been reported positive for heartworm antibodies, indicating exposure to heartworms. Read more >>
Your cat’s indoor lifestyle can reduce exposure to many outdoor risks, but it doesn’t completely eliminate the possibility of encountering an infected mosquito.
Why Heartworm Disease Can Be Difficult to Detect
Diagnosing heartworm disease in cats isn’t always straightforward. Testing can be affected by the stage of infection, and the small number of worms cats typically carry.
Testing performed early in an infection may produce a false-negative result. Low worm burdens can also make heartworm infections harder to identify through antigen testing. These challenges are one reason heartworm disease can be missed, even in cats receiving regular veterinary care.
The American Heartworm Society recommends annual heartworm testing for cats using antibody and heat-treated antigen testing. Heartworm disease should also be considered when cats develop asthma-like respiratory symptoms or gastrointestinal signs such as vomiting.
Regular wellness visits give your veterinarian an opportunity to evaluate changes in your cat’s health, discuss potential risk factors, and determine when additional testing may be appropriate.
Why Year-Round Heartworm Prevention Matters
Preventing heartworm disease requires consistency. Gaps in prevention can leave cats vulnerable to infection and the lung damage associated with heartworm disease.
Leading veterinary organizations, including the American Heartworm Society, Companion Animal Parasite Council, American Animal Hospital Association, and American Veterinary Medical Association, recommend year-round heartworm prevention for cats.
Year-round protection is recommended for indoor cats as well as cats who spend time outdoors. Consistent preventive care helps protect your cat regardless of the season, changing mosquito activity, or how much time they spend outside.
Protect Your Cat with Preventive Care
While heartworm disease can be difficult to recognize and diagnose, consistent preventive care can help protect your cat before heartworms have the opportunity to cause harm.
At Faithful Friends Veterinary Clinic and Cat Specialty Center, we can help you choose a safe and effective parasite prevention plan based on your cat’s age, health, lifestyle, and individual needs. Whether your cat enjoys supervised outdoor adventures or spends every day curled up safely inside, year-round parasite prevention is an important part of keeping them healthy.
If you have questions about feline heartworm disease or your cat’s current parasite prevention plan, schedule an appointment with our team. We’re here to help every member of your feline family stay protected all year long.
