Video: "Heartworm Disease" (3:00)—Dr. Scribano talks about how pets get heartworms, their effects, and how we can help prevent them.
Featured Quote - "The oral once a month prevention methods are good, but they're only good if you give it every single month and most of us are human, not superhuman."
Heartworms are parasites that can grow to be 1 foot long and live inside an animal's heart, arteries, and lungs. They can cause heart failure, lung disease, and other organ damage. While heartworms find dogs to be the more hospitable host, they can also live inside cats, mainly during the younger stages of the heartworm life cycle. Most heartworms in cats do not survive into adulthood, and infected cats typically have fewer than 6 worms. However, even 1 or 2 immature worms can make a cat very sick.
In cats, heartworm disease typically involves the lungs. Smaller immature worms can enter the lungs and cause Heartworm Associated Respiratory Disease, which is severe lung damage.
The key to heartworm infection is the mosquito. Heartworm larvae in an infected animal—another cat, dog, coyote, ferret, or other mammal—circulate through the bloodstream. A mosquito bites an infected animal and ingests its blood, along with the heartworm larvae. The mosquito then bites a pet cat, and the larvae make their way into the cat's bloodstream through the wound.
After about 6 months, the larvae develop into adult worms. Since heartworms can live up to 3 years in cats, mosquito seasons can build up an increasing risk of heartworm disease. Indoor cats are also susceptible to the disease since mosquitoes can enter the home. About 33% of all infected cats are indoor cats.
Heartworm disease in cats is not easy to diagnose. Symptoms can appear similar to the symptoms of other health conditions. They include:
Most tragic of all, a cat may collapse due to respiratory failure—or suddenly die—because heartworms can obstruct the flow of blood through the arteries.
It is important to note that infected cats may never display symptoms at all. That makes regular testing all the more critical. Cats who test positive for heartworm disease require routine care during the heartworm life cycle to monitor possible damage to internal organs.
There is no single heartworm test that can absolutely confirm the existence of heartworm disease in cats. That means a combination of blood tests may be needed to diagnose heartworm disease.
Unfortunately, treatment for heartworms in cats is not available, since current medications to remove heartworms are not suitable for cats, and preventatives only target worms that are still in the larval stages. That means early detection and prevention are the only ways to keep cats free of this disease. Please don't underestimate the value of regular Cat Wellness Exams. Heartworm prevention is available that can be administered either once a month or twice a year. Talk to your vet about which option is best for your cat.