Heartworm is a parasitic infestation transmitted to dogs (and more rarely, cats) by bites from infected mosquitoes. Heartworm is a potentially fatal health threat and often requires aggressive, prolonged and painful treatment.

Heartworm Prevention

Heartworm disease is easier to prevent than it is to treat. The first line of defense in preventing your pet from any disease or infection is through the promotion of a healthy immune support by providing optimal nutrition, exercise and play, minimizing stress, thoughtful vaccination protocols, and veterinary care. According to the Integrated Pest Management Information Network from North Carolina State University, "Healthy animals are best able to withstand and, to some extent, avoid infestation." Dr. Michelle Tilghman, D.V.M. says, "Strengthen [your pet's] resistance with whole foods. Dogs and cats are more likely to resist heartworms when they are given all-natural foods, which help keep the immune system strong."

The next line of defense should be reducing breeding environments for mosquitoes in areas where your pet spends a lot of time. Standing water sources are needed for mosquitoes to breed, so whenever possible it is best to eliminate these breeding grounds, which should reduce mosquito bites to both humans and pets. Products like Garlic Barrier will also help reduce the number of mosquitoes and other unwanted insects in your yard.

The FDA recommends the following preventative measures for ensuring your pet does not succumb to heartworm, which may include tablets, injectables, and topical treatments (these preventatives will require a prescription from your veterinarian):

• oral pill or tablet: ivermectin, milbemycin oxime
• spot on topical treatments: selamectin, moxidectin
• injectable (for dogs only): moxidectin

In addition to these prescribed allopathic preventatives, there are a number of holistic products intended to prevent heartworm infection. Many of these are topical sprays featuring blends of various essential oils. Be very careful using these sprays if there are cats in your home, as they can be toxic to resident kitties. Additionally, there are a wide variety of herbs that are recommended (either topically or internally) for the prevention of mosquito bites and thus heartworm (examples include garlic, black walnut, and mugwort). Some pet owners report great success with using a spray of organic apple cider vinegar.

Talk to your veterinarian about the heartworm preventatives which would be best for your pet. Depending on where you live, you may need to provide heartworm preventatives year round or only in the warmer months when mosquitoes thrive. Ask your veterinarian about seasonal risks and infection rates in your geographic region.

Heartworm Symptoms

Heartworm is a stealthy invader. Worms tend to accumulate gradually in the body, and clinical signs or other obvious symptoms may not appear for months after initial infection.

Signs of heartworm infectio...

Heartworm disease is transmitted to dogs and cats by a bite from a mosquito carrying the microscopic heartworm larvae. Heartworms are a parasite known as Dirofilaria Immitis. They have the appearance of thin spaghetti when they reach adulthood. In dogs, heartworms can grow to an adult length of 10-12 inches. While both cats and dogs can become infected with heartworm, it is far more prevalent among canines. Cat's represent only 10-15% of the heartworm cases in the U.S.

Undetected and untreated, adult heartworms will infect the arteries of the heart and lungs. It is an extremely serious condition and can lead to heart failure in your pet. Heartworms are more common in hot and humid areas where mosquito infestations are heavy. The average annual number of canine heartworm cases is highest in the Southeast region of the United States. Nevertheless, dogs and cats are at risk for heartworm in every state.

What are the symptoms and treatment of heartworm disease?

In cats:

• Inflammation of the arteries and surrounding tissue of the lungs
• Breathing difficulty
• Gagging or vomiting
• Loss of appetite and weight loss
• Lethargy, seizures and fainting
• Cats usually have fewer worms than dogs but one worm can cause a blockage, resulting in a medical emergency and possible fatality
• Diagnosis of heartworm is difficult in a cat. There is no viable treatment for advanced heartworm in felines, so prevention is essential. When diagnosed early the heartworm condition can be improved, but there is no cure.

In dogs:

• Cough and coughing blood
• Weight loss
• Winded after exercise, exhaustion
• Symptoms occur after heartworms reach maturity
• Diagnosis includes a blood test
• Because treatment is difficult, presence of heartworm microfilaria must be confirmed first. Tests to make sure the dog's heart, liver and kidney function are strong have to be conducted as well.
• Currently the most common drug used to treat dogs infected with heartworm is Immiticide, which contains small amounts of arsenic to kill the worms. It is generally given as an intramuscular injection in the lower back, which causes soreness for a few days. Two to three doses are usually required.
• Dogs being treated with Immiticide must have their exercise restricted for several weeks. This is to prevent dying heartworms from causing a blood vessel blockage (also known as an embolism).

Fast Facts about Heartworm Disease

• The normal host for the heartworm parasite is the canine. Heartworm disease is four times more common in dogs than in cats.
• Pets can't catch heartworm disease from each other. Only the bite from an infected mosquito can transmit the parasite to your pet.
• Wild animals that can acquire heartworms include the wolf, fox, coyote, muskrat, raccoon and ferret.
• The first documented mention of heartworm disease in dogs appeared in the 1847 Western Journal of Medicine.
• It takes seven months for the heartworm larvae transmitted by the mosquito to mature in...

Heartworm disease in dogs and cats is variously treatable. While both cats and dogs are subject to heartworm, the illnesses and treatments are different. It is important to know the symptoms, causes and areas at risk and to be prudent in treatment. Although heartworm disease was once confined largely to warm and wet areas, it has now spread globally.

What is heartworm?

The dirofilaria immitis is a roundworm parasite that travels from host to host through the blood, transferred by mosquitoes biting multiple victims. The worm itself is a filament-like, slim worm that completes its life cycle in mammals.

Heartworm in dogs:

In dogs, the adult heartworm takes up residence, sometimes for many years, in the right ventricle of the heart.

Heartworm symptoms may be undetectable after infection and through the early adulthood of the parasite, especially for sedentary dogs, or dogs whose sedentary habits suggest age or fatigue. For active dogs, or dogs with a high rate of infestation, the symptoms can include cough, exhaustion after light exercise, and cough during exercise. Severe signs include weight loss, fainting or coughing up blood and extend to congestive heart failure. Occasionally, but rarely, heartworms may migrate internally and end up causing seizures in the brain, blindness, or lameness.

Heartworm diagnosis is carried out through a blood test for antigens secreted by female worms. For the blood test, a false negative can result if the worm population is low or if all the worms are males. Dogs who test positive for heartworm should have a heart x-ray to see the extent of the worm population in the heart itself.

Heartworm prevention is assisted, but not guaranteed, by removing all damp or standing water areas around the property where mosquitoes can lay eggs. Naturally, if all animals in the area have been vaccinated against heartworm, the possibility to get heartworm is reduced. Your vet may prescribe various types of heartworm medication: ivermectin (Heartguard), milbednycin (Interceptor and Sentinel), or moxidectin (ProHeart 6, pro Heart 12) or may prescribe topical treatments that include imidacloprid & moxidectin (Advantage-Multi) or delamectin (Revolution). You may have to use heartworm medicine for 12 months out of the year if your temperatures never falls below 14C (57F).

Heartworm treatment is a prolonged process because adult heart worms take months to die. Dogs diagnosed with heartworm must be evaluated to make sure they are strong enough to withstand the heartworm treatment. Following evaluation, commonly, melaresomine dihydrochloride (Immiticide) is used. Dogs must rest for several months after treatment to prevent dead worms from entering the lungs. Surgery to remove the worms is possible, but is considered somewhat dangerous.

Heartworm in cats:

Cats are far less likely than dogs to develop heartworm. Typically they get fewer worms and the period of infection is shorter than in dogs. But cats are more lik...