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Cat Heartworm Prevention

Cat Heartworm Prevention in St. Petersburg


The Disease.

How It Is Spread.


How We Help.

Also visit our Dog Heartworm Prevention page.

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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.

Video Transcript:

Hi, I'm Dr. Scribano from Northeast Animal Hospital. Today, we're going to review some things about heartworms disease.


Dr. Scribano, how do our dogs and cats get heartworms?


Heartworms are transmitted through a mosquito bite. Even if I took blood out of an infected animal and injected into another animal, they won't get heartworms. It has to go through the mosquito. The products that we sell have to be in their bloodstream, so that when a mosquito feeds and deposits larvae that they won't make it to be an adult.


How do heartworms affect our pets?


Heartworms accumulate in the heart and the large vessels causing coughing and exercise intolerance. The problem is that those symptoms that you will see are far into the disease and it affects the large organs as well.


How do I know which product is the best to prevent heartworms?


That's a great question, especially now. We are using more of the injectable form just from a compliance standpoint. 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. When we do the statistics - when we read about them - it’s not favorable. The last one I heard was that 93% of all dogs that are positive, the owners say, "Well yes, but they've been on a preventative." That kind of told me that they forgot when they forgot. Maybe six months ago you forgot to give it, maybe he got right back on it, but it let them be open to the mosquito bite six months ago. The orals work right, but you have to give them every month and the animal has to keep it down. Sometimes they might have an upset stomach or something like that or you might find them under your sofa. There's all kinds of reasons, but the statistics don't lie.


In the other compliance studies I've seen, they say that we're successful somewhere around six or seven doses out of the entire year. I'm very much promoting the injectable form, so that I know they have guaranteed protection.


Do I need to use prevention year round?


Yes. Maybe in Canada or something of the Northern climates, the mosquitoes aren't out, and so you can go off prevention certain times of the year and they'll educate you on that. But here in Florida, absolutely, year round, lifelong.


How often should my pet have a heartworm test?


We test dogs annually and we do that through their annual blood work. The heartworm test is included when we do annual blood works. Not only do we get the benefit of an internal exam, but we can let you know if they are positive for heartworms. In the cat, it is not as significant because we can't treat heartworms in the cat anyway.

What is Cat Heartworm Disease?

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.

How Do Cats Get Heartworms?

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.

What Are the Symptoms of Heartworm Disease in Cats?

Heartworm disease in cats is not easy to diagnose. Symptoms can appear similar to the symptoms of other health conditions. They include:

  • Rapid or labored breathing
  • Coughing
  • Vomiting (not necessarily from eating)
  • Fatigue
  • Loss of appetite
  • Loss of weight

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.

How are Cats Tested and Treated for Heartworms?

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.

  • An antigen test can detect the presence of female worms, but since a cat may only have 1 or 2 worms, they might be males only.
  • An antibody test can detect whether the cat's body is currently fighting a worm infection or has fought an infection sometime in the past, but that means a positive test result does not confirm an infection is now present.
  • Radiographs and echocardiograms are used when a cat tests positive to an antibody test; they can help your veterinarian determine the extent of lung and heart disease.
  • Ultrasound can give us a visual clue to the presence of heartworms in the heart or arteries.

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, and of our 20% discount on bloodwork with every routine cat exam. 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.

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