Why is Heartworm Preventative Important?

According to the American Heartworm Association, Rhode Island veterinary clinics have reported between 6 and 25 cases of heartworm disease, per clinic, per year. With populations of coyotes and fox rising in the area and warmer and rainier Springs each year, that incidence is on the rise.  The coyote and fox populations act as a resevoir for the disease.  Mosquitos feed off them, pick up the larval or baby worms, then bite your pet and infect them with the larvae.  Over the next 6 - 8 months, those microscopic larvae grow into 6 - 10 inch adult heartworms that live in your pet's heart causing obstructed blood flow, cardiac enlargement, and lung scarring from chronic inflammation. While heartworm infections in dogs can be treated, the medications used can have side effects, and in advanced cases, the damage to the heart muscle or lung tissue is not reversible and leads to chronic heart failure or respiratory disease. In cats, there is no treatment for heartworm infection.

My pet spends all of his time indoors, so I don't have to worry, right?

WRONG!!!!   All it takes is one mosquito bite from the wrong mosquito and your dog or cat can become infected.  In this area, in dogs, it may take several years to develop illness, or just several months, depending on how many bites and thus how many adult worms. Your dog may not act ill until the damage is irreversible.  In cats, all it takes is one worm to cause signs, and since the most common sign of heartworm disease in cats is sudden death, you may never know there was a problem until it is too late. 

How can I tell if my pet has heartworm disease?

Since most pets do not show signs of illness until their disease is very serious, annual testing is recommended to make sure your pet is not infected.  In dogs, the test is a quick blood test that will check for heartworm infection, and exposure to the bacteria that can cause Lyme disease and Anaplasma.   In cats, they have added a blood test that checks for  Heartworm, Feline Leukemia and FIV.

What is involved in treating Heartworm disease?

 Cats can develop chronic vomiting and asthma from heartworm infections.  Those cats are treated symptomatically until their body can clear the infection.  Dogs with confirmed heartworm disease are started on an antibiotic called Doxycycline that makes the worms more susceptible to the medication that destroys them, Immiticide.   While they are on the antibiotics, blood tests are performed to make sure your dog's kidneys and liver are healthy enough to receive treatment, and radiographs of your dog's chest are taken to look for evidence of heart and lung disease.   

Once the antibiotics are finished, and your dog's test results have been evaluated, your veterinarian will recommend a series of 2 to 3 injections of Immiticide to kill the worms living in your dog's heart.

Once the worm's begin to die,  the body's immune system removes them from the heart and lungs over the next month.  During that time, there is a risk of clots forming around the dead worms that can lead to a stroke, respiratory arrest or sudden death if your dog's blood pressure increases. Strict exercise restriction and often sedation is needed to keep your dog calm while the body recovers from the infection. Three months after the last injection is given, your dog's blood is re-evaluated to make sure the infection  is completely gone.  

How safe is the treatment?

Immiticide is a treatment that has been available  for a little over a decade now, and is much safer than the arsenic based Carparsolate that was once used.  However, the recent issues with our economy led to a closure of the manufacturing company that made the chief ingredient in Immiticide, and Merial is now awaiting approval from the FDA to use a manufacturer that makes the product in Europe.  Until they gain that approval, special approval from the FDA needs to be obtained to treat individual dogs.  For more information regarding Immiticide availablility, please check the Merial Website.

How much does the treatment cost?

The initial test to check for infection is $56 dollars and is usually part of your pet's yearly exam.  If your pet tests positive, the initial lab tests and radiographs cost about $300 - $350.  

Treatment in cats depends on whether they have vomiting or asthma like signs, or have heart failure from the worm living in the heart.  It takes up to 1 year for the worm to die off naturally.  During that time medications and repeated tests can cost $30 - $50 a month at the beginning.  If their signs are irreversible, annual treatment is likely to be $200 - $300.  

Treatment in dogs depends on the severity of cardiac and respiratory disease the worms have caused, and the size of your dog.  Dogs in early stage disease have few complications and may only need two injections.  An otherwise healthy 50 pound dog, with no complications from the infection will cost about $400 to treat.  A 100 pound dog in the same group will cost about $700.  Dogs that have developed changes to their heart or lung function, or have secondary organ dysfunction as a result of poor oxygenation, poor blood pressure, or chronic infection will be twice as expensive as the healthy dogs to treat.

Since the monthly preventative costs less than $100 per year for a dog between 50 and 100 pounds, it is FAR MORE cost effective and certainly Healthier to PREVENT this disease rather than treat it.

For more information on heartworm treatment in dogs, visit the Pet Health Library.

How can I protect my dog or cat from Heartworm infection?

There is a monthly heartworm preventative available for both dog's and cats.  For smaller pet's, there is a topical product called Revolution that protects pet's from heartworm disease, ear mites, intestinal parasites and kills fleas.  For larger pet's, or animals that are at risk for tick infestations, an oral product such as Heartguard, Interceptor or Iverheart is recommended.  All of these medications require an annual physical exam with your veterinarian. 

Dogs must be tested negative prior to starting prevention.  Infected dogs can have baby worms, or larvae, circulating in their blood stream.  The monthly preventative will kill these larvae off.  If enough die at once, it can trigger a potentially life threatening allergic, or anaphylactic, reaction.  Since cats are accidental hosts of heartworm, the adults do not live long enough to produce larvae.  Therefore cats do not have to be tested prior to administering heartworm prevention.

Heartworm prevention should be given to your pet EVERY MONTH, ALL YEAR ROUND, ALL THEIR LIFE.  With the increased population of resevoir species like coyotes, warmer and wetter springs, and later and later frosts, your pet is at risk all year round.  A dog that is predominantly indoors, usually still goes outside to urinate and defecate.  Dogs and cats that are housebound are less at risk, but bugs have a way of getting inside, especially mosquitos, so prevention is recommended regardless.  Currently, the number of reported cases of heartworm disease in cats is negligible in this area. However, the most common result of heartworm infection in cats is sudden death from thrombolic disease, or clots.  If you are paying for flea prevention on your cat, you might as well use Revolution and protect your cat from heartworm and fleas.  If you are interested in receiving a monthly reminder for your pet's heartworm prevention, please join the hospitals Facebook page. We send an update at the first of each month to remind folks to give your dog and cat his montly medication, or send us an email to join our mailing list. You will receive a copy of the monthly newsletter in addition to a reminder to give your pet his or her heartworm and flea/tick prevention. 



For More Information

For more information about heartworm disease in your pet, visit the links below, or call your veterinarian, and PLEASE, remember your pet's medications. 

Amercian Heartworm Society

Pet Health Library

FAQ's of Heartworm Infection 

Does it matter where I get Heartworm Prevention From?

While most online pharmacies are reputable, some are not.  The best way to be sure is to make sure the site is certified by the Veterinary Internet Pharmacy Practice Site, or VIPPS . 

Please remember, that if you choose to purchase your Heartguard on line, they will NOT be guaranteed by the manufacturer. 

If your pet tests positive for the heartworm or intestinal parasites the product was meant to prevent, Merial will contribute $500 toward veterinary care, and cover the cost of medications to treat the infection ONLY if you have purchased your Heartgard  from a licensed veterinarian.

The guarantee the internet sites offers is not from Merial, and only refunds what you paid for the Heartgard, NOT THE TREATMENT.   In most cases, The medications will only be a few dollars more at your veterinarians. 

It is also important to remember that you will still need to visit the veterinarian to get prescription medications, as your dog or cat will need, at the least, an annual exam, and possibly a blood test to make sure they are healthy enough for the medications. If you are unsure of what would be best for your pet, please call your veterinary clinic for appropriate recommendations.