What Is Dirofilariasis, AKA: Cat Heartworm?

 

Dirofilaria immitis is a blood-borne parasitic nematode (roundworm), commonly referred to as heartworms (or heartworm disease). Heartworms in cats are spread through mosquitos carrying cat heartworm larvae. The severity of heartworms in cats is directly dependent upon the number of worms present a cat's body, the duration of the incubation, and the response of the infected cat.

 

 

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The way that heartworm disease affects cats is different from dogs. What happens is that it's sort of an end stage disease of a cat instead of actually becoming a worm in the heart, and it creates some pretty significant chronic and permanent lung changes.

Video Transcript:

So the way a heartworm is transmitted is that a mosquito takes a blood meal from an infected animal, either a dog or a cat, and then it comes into your yard or your house and it will bite your cat or dog and inject the microfilariae through the bite and infect your cat or dog with heartworm disease.

The way that heartworm disease affects cats is different from dogs. What happens is that it's sort of an end stage disease of a cat instead of actually becoming a worm in the heart, and it creates some pretty significant chronic and permanent lung changes. It's almost like an asthmatic problem for cats, or it creates one big nodule in their lungs. Actually, it looks like a tumor, but it's where the worm finally landed, and it doesn't create the same type of disease in the heart, but it does create a very bad illness in cats.

We do recommend this pretty much for all cats. While outdoor cats are more exposed, indoor cats are also exposed because mosquitoes do come inside.

This is Moki, and he's our house cat, and he wanted you to know that this is his first choice. Revolution is Smokey's first choice for a heartworm infection. It's also a great product for killing roundworm, hookworm, and rope worm.

It's pretty good for a flea control also. The reason we like this product, or the cats really recommend this product for would be other cats because they're exposed to lots of different things that indoor cats are not exposed to.

We recommend this. It's a once-a-month topical that you use on your cats and it prevents heartworm, some intestinal parasites, and it does a pretty good job killing fleas that they've been exposed to also.

Although heartworms in felines are less prevalent than in canines, feline heartworms are still a dangerous disease that has been on the rise in America. The risk of heartworm is about equal for both indoor and outdoor cats. If you do not use preventive medication, the risk of contracting cat heartworm disease exponentially increases. This is why preventive cat heartworm medication is so important.

Symptoms Of Cat Heartworm Disease

One of the most challenging aspects of diagnosing heartworms in cats is that there are no definitive clinical signs that directly indicate the existence of cat heartworm disease. However, this doesn't necessarily mean that cat heartworm disease isn't present. Some health signs that might indicate the presence of cat heartworm disease include:

Vomiting and coughing are two of the most common symptoms but there may be other symptoms, including:

  • Difficult or labored breathing
  • Convulsions
  • Blindness
  • Lethargy
  • Anorexia/Weight Loss
  • Fluid in the lungs
  • Sudden Death

On occasion, an apparently healthy cat may be found dead, or may develop sudden overwhelming respiratory failure. In these cases, cat heartworm disease may be diagnosed on a post-mortem examination.

We can easily prevent cat heartworm long before serious medical issues or life threatening emergencies develop by simply implementing preventive measures.

How Are Cat Heartworms Transmitted?

Upwards of 30 species of mosquitoes can act as cat heartworm transmitters. Mosquitoes ingest immature heartworm larvae, called microfilariae, by feeding on either an infected cat or dog. The microfilariae develop further for 10 to 30 days in the mosquito's gut and then enter parts of its mouth.

When an infected mosquito bites a cat, it injects the heartworm larvae into the cat. The larvae then migrate and mature over a period of several months, eventually ending up in the right side of the heart and the pulmonary arteries. Once this occurs, they mature into adult cat heartworms, and can reproduce about six months from the time of invasion. Approximately eight months after the invasion, cat heartworm begins to produce a new crop of microfilariae that will live in the cat's blood for about one month. By the time this occurs, most cats begin showing symptoms of cat heartworm and the disease can become fatal very rapidly.

Diagnosing Heartworm For Cats

Unfortunately, there is no one benchmark standard used across the veterinary industry for diagnosing heartworm for cats. Rather, our veterinarians employ a battery of lab tests in order to determine a cat heartworm diagnosis. These tests include:

  • A urinalysis, or the testing of a cat's urine.
  • A heartworm antibody test determines whether or not a cat's immune system has been exposed to heartworms. This is a very sensitive test, and is usually employed first.
  • A heartworm antigen test determines the presence of adult female heartworms. This is more specific than an antibody test, but not as accurate in all cases with cats because they will sometimes only have male worms present.
  • Radiographs, or X-Rays, that allow us to view the size and shape of a cat's heart. This is helpful because many cats with cat heartworm develop enlarged pulmonary arteries, or have obstructions in the arteries leading to the lungs.
  • Ultrasounds allow us to view the internal structures of the heart and surrounding vessels, in order to assess the condition and function of the heart. However, in some cats with low levels of cat heartworms, this test does not always yield accurate results.
  • A white blood cell count can be measured in cats suspected of having contracted heartworms. Eosinophils are a type of white blood cell which occur in higher numbers when heartworm for cats is present, but can also indicate the presence of other parasites besides cat heartworm.

Heartworm Medicine For Cats

Unfortunately, there is currently no viable heartworm medicine for cats that can fight off an active infestation. Therefore, if your cat is diagnosed with heartworm, we cannot cure it. However, while we cannot defeat existing heartworm disease with medication, this isn't necessarily an indication that they will die soon. While sudden death is possible, it isn't common. If your cat is diagnosed with heartworm they may still live a long life under the supervised medical care and treatment of your veterinarian. This may include anti-inflammatory treatments and medications to aid in breathing, similar to those used to treat asthma.

Heartworm Prevention For Cats

The good news for cat owners and their feline friends is that reliable heartworm prevention for cats does already exist. Veterinarians strongly recommend that all cats receive monthly heartworm preventive medications in areas where mosquitoes are active all year round. Here in California and because of our mosquito population, we highly recommend all cat owners adhere to this annual preventive medicine protocol.

Have A Veterinarian Check Your Cat For Heartworm At Your Next Appointment

We recommend scheduling an appointment to discuss heartworm prevention for cats with us before your cat contracts heartworm. If you witness any symptoms that might be indicative of cat heartworm disease, please contact us immediately to schedule an appointment. Our veterinary team will provide you and your feline friend with an effective cat heartworm prevention protocol.