What happens to a cat infected with heartworm? Causes, symptoms, and treatment are also explained.

Spring is the season for "rabies prevention" and "heartworm prevention." While you might think both are for dogs, that is not the case. In fact, heartworm disease is a condition that can also infect cats.

Heartworm disease in cats is a very scary illness that can also be life-threatening.

In this article, we will explain in detail what heartworm disease in cats is and how to prevent it.

What is heartworm disease?

First, let’s understand what heartworm disease is.

Causes of heartworm disease

Heartworm disease is an infectious disease caused by the infestation of a parasite called heartworm. The scientific name for heartworm is "Dirofilaria immitis," and it primarily infests dogs.

The route of transmission for heartworms is "mosquitoes." When a mosquito bites an infected dog and then bites another dog, the larvae enter the new host's body.

Once the heartworm larvae enter a dog’s body, they travel through the blood vessels and grow into thread-like adult worms in the heart and lungs. At the larval stage, they are about 1mm long, but as adults, they can reach 15 to 30 cm in length.

Dozens of worms can infest a dog at once, and it is said they can survive inside the dog for about five years.

Symptoms of heartworm disease

Heartworm infestation places a burden on the heart and lungs. As a result, symptoms such as heart attacks, ascites due to heart failure, fainting, and coughing appear. Symptoms may not appear until years after the initial infection.

Adult worms can clog blood vessels in the heart, leading to sudden death.

Treatment for heartworm disease

You can determine if an animal is infected with heartworm through a blood test. Once a heartworm infection is confirmed, the parasites are removed through anthelmintic medication or surgery.

What is heartworm disease in cats?

As explained above, heartworm disease is more common in dogs, but it is known that it can rarely infect cats as well.

The route of transmission is the same as in dogs. However, because dogs are the natural host for heartworms, most larvae are said to die within a cat's body.

The problem with heartworm infections in cats lies precisely there.

"Immune response to dead heartworm larvae" and the fact that "few heartworms grow to adulthood, making them difficult to detect via blood tests" make it very difficult to diagnose.

Symptoms of heartworm disease in cats

Just like in dogs, heartworm disease is life-threatening for cats.

When dead heartworm larvae reach the lungs, the immune response causes respiratory symptoms such as coughing and difficulty breathing. Other symptoms include vomiting, loss of appetite, lethargy, and weight loss.

Also, as with dogs, there is a risk of sudden death if adult heartworms clog the heart's blood vessels.

In all cases, it is currently very difficult to detect through testing, making diagnosis a challenge.

Treatment for heartworm disease in cats

In cats, the immune response to dead heartworms can be very severe. Therefore, treatment with anthelmintic medication is not suitable.

Furthermore, surgery for a small cat must be carefully considered.

To prevent symptoms from worsening, treatment focuses on symptomatic therapy, such as the use of steroids. Depending on the symptoms, lifelong medication may be required.

Prevention is necessary for cats, too!

Since the cause of heartworm disease is "mosquitoes," there is a risk of infection even for strictly indoor cats. Because the disease is difficult to diagnose and treat, preventative measures are necessary for cats as well.

How to prevent heartworm disease

Heartworm disease in cats can be prevented with medication. These are often "spot-on" types that you apply to the back of the neck, so even cats that dislike medication can be treated without stress. Very few adverse reactions have been reported.

Commonly used heartworm preventatives for cats include "Revolution" and "Broadline." In addition to heartworms, they are also effective against fleas and ticks.

Because the necessary heartworm prevention medication varies depending on the cat’s lifestyle and the region, be sure to have it prescribed by a veterinarian.

When and how long is prevention needed?

Heartworm preventative medication is effective when applied to the back once a month. Since heartworm is a mosquito-borne disease, medication is necessary from the time mosquitoes begin to emerge until they disappear.

As a general guideline, medication is given monthly from May to around December. In Hokkaido and the Tohoku region, it may be needed from June to November, and in Okinawa, year-round administration may be necessary.

Cost of heartworm prevention

The average cost for feline heartworm prevention is about 2,000 to 4,000 yen per dose. You would purchase the amount needed for the required number of months.

Since the cost varies depending on the cat’s weight, the type of preventative, and the duration of the season, check with your veterinary clinic regarding the costs.

Summary

Heartworm disease can also infect cats. Larvae entering the body via mosquito bites can grow into adult worms in the heart or lungs, causing serious symptoms. It is known to be a scary disease that can also cause sudden death.

However, it is a preventable disease with proper measures. Of course, prevention is necessary even for strictly indoor cats.

It is a good idea to note your monthly medication schedule on a calendar or in a cat-specific health record book. Don't forget to combine flea/tick and heartworm prevention with your annual check-up and vaccinations.

To ensure your beloved cat stays healthy and lives a long life, make sure you are correctly informed about feline diseases and prevention.

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