While you may have heard of heartworm disease, many cat owners don’t know what it really is and the true risk these parasites pose for their cat’s health. Below you can find quick facts, more detailed explanations, and tips for helping you keep your cat safe. If you ever have questions about heartworm, reach out to your local vet who can help answer.
Heartworm in Cats: 7 Quick Facts
Heartworms are transmitted to cats through the bite of an infected mosquito.
Contrary to its name, the most affected organ in cats are the lungs.
Heartworms can live 2-3 years inside a cat.
There are limited, non-invasive treatment options for heartworm in cats; however, there is no cure.
Some cats can outlive the heartworms with intensive symptom management, but fatality occurs in approximately 50-75% of infected cats.
Cats often show little to no symptoms of the disease until an acute respiratory episode or collapse occurs.
Feline heartworm is preventable with a simple monthly medication.
What Is Heartworm in Cats?
Heartworm is a parasitic infection that affects cats of all ages, breeds, and lifestyles. It is caused by a parasitic type of roundworm known as Dirofilaria immitis, which lives in the heart, lungs, and blood vessels of infected cats. If left untreated, the worms can cause serious medical complications, including heart and lung damage, organ failure, and even death.
Heartworm disease in cats is particularly dangerous because cats are not natural hosts for heartworms. This means that the worms often do not reach full maturity, but even immature worms can cause significant health issues. The worms can obstruct blood flow and cause severe inflammation in the lungs, leading to respiratory distress and other complications.
How Do Cats Get Infected with Heartworm?
Heartworm is passed to cats through the bite of an infected mosquito. When a carrier mosquito bites a cat, the heartworm larvae enter the cat’s bloodstream. The larvae travel inside the cat’s blood, often settling inside the lungs, where they mature into adult worms. The lifecycle of heartworm begins when a mosquito bites an infected animal and ingests microfilariae (baby heartworms) present in the blood. These microfilariae develop into infective larvae within the mosquito over about 14 days (about 2 weeks). When the mosquito bites another cat, the infective larvae are transmitted and begin their journey to the lungs and heart.
How to Tell If Your Cat Has Heartworm
Heartworm disease is often described as “The Silent Killer” in cats since the signs can be very subtle and typically indistinguishable from other respiratory diseases. When symptoms are present, they tend to be similar to those of asthma or bronchitis due to the severe inflammation caused by the worm inside the lungs. Some symptoms can include:
Coughing, Wheezing, and Difficulty Breathing: Persistent cough that may sound like hairball-like retches.
Difficulty Breathing: Labored or rapid breathing, like asthma-like attacks.
Occasional Vomiting: Vomiting that may occur sporadically.
Poor Appetite & Weight Loss: Reduced appetite and unexplained weight loss.
Lethargy & Fainting: General tiredness and potential fainting spells.
Seizures: In rare cases, seizures may occur.
Routine lab testing before clinical signs begin is crucial. Feline heartworm antibody testing can be done annually and routinely at your vet to catch the infection early. The early respiratory signs unfortunately tend not to be identified until a worm dies within the lungs of a cat, sparking an acute inability to breathe that can lead to shock and loss of life.
Diagnosing Heartworm in Cats
Diagnosing heartworm in cats can be challenging due to the small size of a cat’s blood vessels and the typically small number of worms present. Often multiple tests are required to diagnose heartworm in cats. These tests may include:
Heartworm Antibody Test: This test can identify exposure to heartworm larvae.
Chest X-rays: Imaging to detect changes in the lungs and heart.
Echocardiography: Ultrasound imaging to visualize the heart and blood vessels.
Physical Examination: Clinical signs and symptoms observed by the veterinarian.
A combination of these tests can help diagnose. A blood test, such as the antigen test, can also be used to detect the presence of heartworm proteins in the blood. However, due to the small number of worms in cats, these tests may not always be conclusive.
Heartworm Preventive Options for Cats (Like Bravecto Plus)
Preventing heartworm in cats is crucial to avoid the severe complications associated with the disease. Feline heartworm is preventable with a simple monthly medication. There are several options available, including oral and topical medications. It is important to administer these medications exactly as directed and to keep your cat on a year-round prevention plan. In the US market today, there are multiple options for feline heartworm prevention; your veterinarian can help you decide which product is best suited for your cat. Whichever option you choose, just remember to administer it exactly how and when directed—set a reminder on your phone, write a note on your fridge, or use Autoship options so you don’t forget!
Oral Heartworm Medications for Cats
Topical Heartworm Prevention for Cats
Liquid Application: A liquid that is applied to the skin at the base of your pet’s neck (where he/she cannot lick it away).
These topical options also help prevent other pests such as fleas and ticks (both of which can carry deadly diseases for humans too!).
Be careful and use a topical medication that prevents heartworms, not just fleas and ticks! Revolution Plus and Bravecto Plus is often recommended for cats and is available at most veterinary clinics.
The Importance of Regular Vet Visits
Regular veterinary checkups are essential for maintaining your cat's health and preventing heartworm disease. During these visits, your vet can perform heartworm tests to ensure your cat is free from infection. Annual testing is recommended even if your cat is on preventive medication, as no preventative is 100% effective. In addition to heartworm testing, your vet can provide guidance on the best preventive measures for your cat based on their lifestyle and risk factors. They can also monitor your cat's overall health and catch any potential issues early, ensuring your feline friend stays happy and healthy.
Understanding the Risks and Complications
Heartworm disease in cats can lead to severe complications, including:
Respiratory Distress: Due to inflammation and obstruction in the lungs.
Heart Damage: Although less common than in dogs, heart damage can occur.
Organ Failure: Severe cases can lead to failure of vital organs.
Blood Clots: Worms can cause blood clots, leading to further health issues.
Caval Syndrome: A life-threatening condition where many worms obstruct blood flow, requiring immediate surgical removal of the heartworms.
Signs of Heartworm Disease in Cats
Cats often show little to no symptoms of heartworm disease until an acute respiratory episode or collapse occurs. The signs of heartworm disease can be subtle and may include coughing, difficulty breathing, and lethargy. In some cases, cats may experience seizures or fainting spells. It is important to be vigilant and seek veterinary care if you notice any unusual symptoms in your cat.
Treatment Options for Heartworm in Cats
There are limited, non-invasive treatment options for heartworm in cats, and there is no cure. Treatment typically focuses on managing symptoms and providing supportive care. Some cats can outlive the heartworms with intensive symptom management, but loss of life occurs in approximately 50-75% of infected cats. Treatment may include:
Corticosteroids: To reduce inflammation in the lungs.
Bronchodilators: To help improve breathing.
Antibiotics: To treat secondary bacterial infections.
Supportive Care: Including oxygen therapy and fluid management.
No matter which state (even with cooler climates)—heartworm disease is a serious threat to cats. But with proper prevention and early detection, it can be avoided. By understanding the risks, symptoms, and treatment options, cat owners can take proactive steps to protect their beloved pets from this dangerous parasite. Remember, prevention is always better than treatment. Keep your cat on year-round heartworm preventive medication, use mosquito repellents, and schedule regular vet visits to ensure your cat remains heartworm-free. Your feline friend deserves the best care, and with these measures, you can help them live a longer, healthier, and happier life. Book an appointment at
your local Thrive Pet Healthcare hospital to discuss which product is best for your feline friend so they can live healthy and heartworm-free for many years to come!
