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Heartworm’s in Household Cats- Rare but Serious

Heartworm’s in Household Cats- Rare but Serious

AUBURN, Ala.- Heartworms, also known as Dirofilaria immitis, infect household cats just like they can infect any other animal. Since cats are an atypical host for heartworm parasites many people believe cats are not susceptible to heartworm disease.

Heartworm disease  affects cats differently from dogs. Heartworms rarely mature to adulthood in cats and therefore, only live for two to three years, at most. However, even immature heartworms can cause serious damage, such as Heartworm Associated Respiratory Disease, or HARD.

Unlike dogs that can carry at least 30 heartworms at once, cats typically carry very few. Heartworms are less likely to mate and reproduce in cats because they don’t usually reach maturity. However, cats that have even just one worm can encounter serious health risks.


“Female adult heartworms living in a host produce microfilaria, or baby heartworms, that live in the host’s bloodstream. When a mosquito bites an infected animal, the microfilaria transfers to the mosquito in the blood. Over the next 10 to 14 days, the microfilaria go through an “infective stage” and become infective larvae,” said Dr. Xing Ping Hu, an Extension specialist and Auburn University professor in Entomology and Plant Pathology.

“When a mosquito carrying the infective larvae bites an at-risk animal, the larvae is left behind on the skin to enter the bloodstream through the mosquito’s bite wound. It takes approximately six months for the larvae to mature to adulthood, however many heartworms don’t make it that far in cats,” Hu added.

Veterinarians test cats for heartworms by taking a small sample of blood. Many veterinarians test for antigens and antibodies. The antibody test looks for exposure to heartworm larvae. Some veterinarians also run X-Rays and Ultrasounds to look for the heartworms.

“Typically, blood tests aren’t done every year for cats. We, instead, run tests for a cat exhibiting clinical signs to diagnose the disease,” Dr. Chris Lea, DVM at the Auburn University Veterinary Clinic said.

Cats should be tested before beginning a preventative routine, however. In addition, cats should be retested if there is a missed dose or lapse in treatments. Owners should consult the cat’s veterinarian for protocol regarding frequency of testing for each type of heartworm medication.

Heartworm Disease Symptoms in Cats

Symptoms of heartworm disease frequently goes unnoticed, as the symptoms can be very subtle. Sometimes, however, the symptoms are very dramatic and can include coughing, asthma-like attacks, occasional vomiting, loss of appetite or weight loss. In rare instances, difficulty walking, fainting or seizures and fluid in the abdomen can occur.

Treatment options are not as readily available to cats as they are to dogs. Treatment options for dogs can be harmful to cats. There really isn’t a guaranteed treatment plan. Because the heartworms rarely live to maturity in cats, the problem can fix itself but it can also lead to long-term damage, such as damage to the respiratory system.

The American Heartworm Society suggests actions owners can take to care for the cat and help alleviate some discomfort. First, diagnose the problem and confirm the disease and its multitude. Unlike with many dogs, the number of heartworms can have a huge impact on the outcome of the disease.

Treatment Options

Although there are no real treatment options available, veterinarians can stabilize the disease and determine a long-term management plan. Also, the veterinarian can determine medical options to alleviate any pain the cat may be experiencing. Monitoring the cat is vital in case the cat experiences a spontaneous clearing of worms and problems arise.

Based off the cat’s symptoms and progress, providing veterinary care may be necessary. Sometimes heartworms are removed. Sometimes cats need fluids or antibiotics, such as an anti-inflammatory. Veterinarian care aids in the cat’s overall well being. Throughout the process it is important to maintain preventative measures to keep the cat from becoming further infected.

There are many prevention options available to pet owners today. The two most popular ones for cats are spot-on treatments and oral pills.  Do these prevention options on a monthly basis.

“We do not use the same treatment for cats as dogs. “My best advice is to ask your vet which products they prefer for cats,” Lea said.

Lea suggests year-round full-spectrum parasite control, as it protects against heartworms in addition to other diseases.

Although it is difficult to diagnose heartworm disease in household cats, it is vital that pet owners take an active stance in heartworm prevention. Pet owners should combat the rising prevalence numbers in order to protect themselves, their pets and their communities from this disease.

For more information, visit the American Heartworm Society website, www.heartwormsociety.org, or the Companion Animal Parasite Council, www.capcvet.org. For more information on the Auburn University Veterinary Clinic, visit www.vetmed.auburn.edu/clHe

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