Heartworm disease is becoming more common, despite budget-friendly and easily administered preventive options, according to the Companion Animal Parasite Council. The prevalence of heartworm-positive dogs has risen 20 percent since 2013. Dogs are a natural host for heartworms, but cats—even indoor cats—can succumb to this potentially fatal disease.
Transmission of heartworm disease in cats
Your neighbor may have an infected dog whom a mosquito can bite and pick up heartworm larvae while feeding. After 10 to 20 days, the larvae, or microfilariae, have reached the infective stage and can infect a new host. The mosquito searches for a new meal and flits into your home, because no home can completely keep out bugs. As your cat suns herself in your window seat, she feels a sharp prick—the neighborly mosquito depositing heartworm larvae that quickly swim into their new home and take up residence in your cat’s bloodstream. Six months later, these immature heartworms have caused mass destruction during the time they reached adulthood. Unlike in dogs, immature heartworms in cats cause more disease signs than the adults.
Signs of heartworm disease in cats
Cats also are less likely to harbor numerous heartworms than dogs. Often, only one to three worms infect cats, but even one adult heartworm can be fatal. Immature heartworms can also cause serious damage. Young heartworms that travel to the lungs’ blood vessels often die and cause a condition known as heartworm-associated respiratory disease (HARD). Signs of heartworm disease in cats include:
- Asthma-like attacks
- Rapid breathing
- Decreased appetite
- Weight loss
- Difficulty walking
- Fainting episodes
Cats may completely clear a heartworm infection on their own, because dogs are the heartworms’ host preference and the worms cannot reproduce inside a cat. But, a cat’s immune system sees heartworms as invaders and works to eliminate them, which can occasionally cause fatal reactions. An apparently healthy cat may be found dead, and a post-mortem exam will reveal evidence of heartworms. Sudden death is thought to be due to a severe anaphylactic reaction, since cats are not the preferred host of heartworms.
Diagnosis and treatment of heartworm disease in cats
Diagnosis is often challenging because of the few adult heartworms present in an infected cat. Multiple blood tests, chest X-rays, and a cardiac ultrasound or echocardiogram are necessary to confirm a heartworm diagnosis.
Once your cat is confirmed with heartworm disease, the symptoms must be managed until the heartworms die. No approved treatment for adult heartworms is available for cats and veterinary care focuses on minimizing heart and lung damage and reducing the inflammation. Treatment for heartworm-positive cats involves exercise restriction, corticosteroids to reduce inflammation, and antibiotics to weaken the heartworms. Surgery to remove the adult worm or worms may be an option. Within two years, all the heartworms in an infected cat should be dead, as long as a preventive product is administered appropriately.
Prevention of heartworm disease
Heartworm disease is a highly preventable condition that is significantly easier to prevent than treat. Keep your pet safe from this potentially life-threatening disease with the following actions:
- Routinely administer heartworm prevention. Cats are tricky to medicate, so choose a heartworm-preventive product you are certain you can give. Many cat owners opt for a topical rather than oral heartworm preventive to avoid pilling their pet. Regardless of the heartworm-prevention product you choose, administering the recommended dose is vital.
- Create a reminder system to avoid forgetting a dose. Many preventive products include a reminder system to help pet owners medicate their cats appropriately. Some manufacturers send texts or emails, while other products include reminder stickers.
- Give heartworm prevention all year-round. Mosquitoes aren’t just summertime pests—they also enjoy a cozy, warm home in winter, especially one with an unprotected pet. Any time the temperature is above freezing, mosquitoes can pop back up and infect your pet.
- Think 12. This simple statement, an ongoing American Heartworm Society initiative, urges pet owners to administer heartworm preventives 12 months a year and test for heartworm disease every 12 months.
Do you think your indoor cat is safe from heartworm disease? Think again. Approximately one-third of all infected cats live indoors only. Stop by our clinic and stock up on heartworm preventive.