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  • Writer's pictureKelly Rachal

Heart-worm disease is a common yet serious and even fatal disease of pets.

The adult heart-worms can grow up to 12 inches in length. These adult worms live in the heart, lungs and vessels of dogs, cats and ferrets. They can also be found other mammals such as foxes, wolves, coyotes, sea lions and even humans. Heart-worms cause damage to vital internal organs and their associated vessels leading to heart failure and lung disease as well as liver and kidney damage. Heart-worm disease is most prevalent in warm, humid areas where the mosquito populations are numerous and thriving. The dog serves as the natural host for heart-worms. This means that heart-worms can live inside of the dog's body and mature into adult worms. Once they are adults and become sexually mature, they begin to mate and produce offspring within the host dog. As they continue to reproduce, hundreds of these foot long worms can accumulate within the dog's heart and lungs. In addition they produce immature, baby worms or microfilariae which migrate throughout the vessels in the dog's body. As you can guess, this can cause severe long term, life altering damage and even death if left untreated. Even after treatment the damage may persist causing adverse effects to your pet's health and overall quality of life. You can protect your pet and preserve their health simply by committing to consistently keep them on heart-worm prevention. Heart-worm prevention not only protects your pet from contracting heart-worms but it also serves to protect them from intestinal parasites. Some products even offer your pet protection from fleas and ticks. Below we have provided graphs and case numbers from reported cases of heart-worm disease and external parasites in pets across the United States. As you will see southern states are high risk areas for heart-worm disease and year round external parasite exposure. While your pet may spend a majority of their time indoors, we assure you these parasites can easily find their way into your home. Think for a minute...have you ever swatted a fly or mosquito in your home or on your car windshield while driving down the road?

Heart-worm disease in cats is very different from the disease process in dogs. The cat is considered an atypical host for heart-worms. This means that most heart-worms do not mature into adult worms in the cat's body. If the microfilariae do mature into adult worms within a cat there is typically only a population of 1 to 3 adult heart-worms. Most of cases of heart-worms in cats are undetected or not diagnosed until the cat develops severe and life threatening illnesses. Many cats affected by heart-worms have no adult worms and the tests we use to screen for heart-worms detects the antigen produce only by adult heart-worms. For this reason heart-worm disease often goes undiagnosed in cats.  These immature heart-worms cause severe damage throughout a cat's body despite their small size. A common condition that is documented in cats in known as heart-worm associated respiratory disease or HARD. There is no approved treatment to kill heart-worms in cats, therefore the only way to protect your feline companion from developing heart-worm disease or HARD is to keep them on a consistent monthly preventative. Unfortunately there is not an injection label for cats to use as a heart-worm preventative as there is for dogs.

Heart-worm disease in ferrets is similar to that in cats. Ferrets develop difficulty breathing, may cough and their gums will commonly turn a light grayish color. Heart-worms block the vessels in a ferret's heart and lungs as well as the surrounding vessels causing severe damage and disrupting normal blood flow. Sudden death is a common occurrence in ferrets suffering from heart-worm disease.

As far as heart-worms in humans goes, don’ be alarmed as you do not get exposed to heart-worm through contact with your dog, cat or ferret. Heart-worms are only transmitted by mosquitoes which carry the infection. For the most part, heart-worm microfilariae die attempting to migrate their way through the skin of a human. If they do succeed in migrating into a human's bloodstream, the microfilariae cannot mature into adults within a human's body and will eventually die. The human body reacts to their death by creating inflammatory tissue in the lungs called pulmonary dirofilariasis. These lesions will show up on radio-graphs and CT imaging as dark spots in the edges of the lung. Heart-worms are not considered to be a serious risk in humans unless they cause pain, discomfort or other clinical signs in the individual.

If my pet tests positive for heart-worms how will they get treated for heart-worm disease?

Heart-worm treatment protocols may vary based on an individual patient's need, but we follow the recommendations made by the American Heart-worm Association. Unfortunately, the is no approved treatment for killing adult heart-worms in cats or ferrets and they require direct medical attention and care by your veterinarian. My A.R.K. Center treatment protocol for dogs is described as followed: * When your dog is diagnosed with heart-worm disease, he or she will immediately be started on a heart-worm prevention. This will prevent further infection and damage done by the microfilariae or baby heart-worms. We will most likely put your dog on the Proheart injection which is an injection that lasts for a period of 6 months. This 6 month injection aids in compliance and omits having to remember to give your dog a monthly prevention during the melarsomide treatment process. We understand that between giving your pet the prescribed daily oral medications during the treatment process and making his or her scheduled veterinary appointments things can be overwhelming. We hope to eliminate some of your worries and stress by administering Proheart to your pet under our direct supervision. If your pet’s condition is advanced or severe additional steps may be necessary to stabilize them prior to, during and possibly even after the treatment process. Please note that adult heart-worms live in the heart and lungs of pets and therefore can wreak havoc on these areas as well as other organs in their body. * Your dog will start taking oral medications. The first medication being prednisone, a corticosteroid. Prednisone works to reduce the chances of your pet having a bad reaction to the death of the microflaria and adult heart-worms. Corticosteroids are usually prescribed in a tapering dose which our staff will explain in detail to you during the discharge process. Corticosteriods are known to cause your pet to drink more water than usual, therefore causing them to urinate more frequently. Inside accidents may occur, but please remember this is a side effect of the medication. Blame the medication and not your pet. Committing to more frequent potty breaks for your pet will likely decrease the amount of inside accidents. The second medication is Doxycycline which is a broad spectrum antibiotic with anti-inflammatory properties. Doxycycline is given continuously for 30 days. * When your pet finishes their month of Doxycycline they will come in for a day appointment in which blood-work will be done to access their internal organ function as well as radio-graphs will be taken of your pet to evaluate his or her heart and lungs. These diagnostic tools will help us to stage your pet's heart-worm disease and make any necessary modifications in their treatment protocol. * Once your pet's heart-worm disease is staged, he or she will be scheduled to receive their first melarsomide injection. This will be approximately two months after your pet starts taking the oral Doxycycline. Your pet will be hospitalized and stay overnight with us in order to be monitored closely by our trained staff. Your pet will be discharged on restricted activity level, oral prednisone and possibly oral Doxycycline depending upon your unique pet's needs. Your pet will need to be monitored for any reactions or side effects over the next 30 days. * One month after your pet received their first melarsomide injection, they will return to receive the second and third melarsomide injections. They will be hospitalized and stay with us for two consecutive nights in order to be closely monitored by our trained staff. Your pet will be discharged on restricted activity level and possibly oral medications. Your pet will need to be monitored for any reactions or side effects over the next 2 months. * Six months after receiving the third melarsomide injection your pet will be tested again for heart-worms via a blood smear (microfilariae) and an antigen test. At this time time your pet should be heart-worm

negative on both tests. If that is not the case with your pet, do not be alarmed as in may take a year for the antigen test to yield a negative result due to its sensitivity.

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