Heart Worm Medication for Dogs
Heartworm disease is a serious and potentially fatal condition affecting dogs. Fortunately, heartworm infection is highly preventable. Should a dog become infected with heartworms, treatment is available, although prevention is safer and less expensive. All dog owners are strongly encouraged to use heartworm prevention medication.
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What are Heartworms?
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Heartworms are parasites that live in the lungs and hearts of infected animals. Female adult heartworms release microfilariae into the bloodstreams of their hosts, where mosquitoes then inject the microfilariae. When the mosquito bites another animal, the microfilariae are deposited into the bloodstream and travel to the lungs and heart, where they mature and begin the cycle again. Heartworms are present throughout the United States, but risk is extremely high in the southern parts of the country. Infected animals will eventually develop heartworm disease, and will often die if the condition is left untreated.
Topical Prevention
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Heartworm prevention is less expensive and less risky than heartworm treatment. There are two main types of prevention: topical and oral. Topical preventions are generally either selamectin or moxidectin medications. Both work to prevent the development of the microfilariae into mature parasites, and slowly clear the bloodstread of the microfilariae. The most common brands of topical prevention are Revolution (selamectin) and Advantage Multi (moxidectin).
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Oral Prevention
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The most common oral preventative medication is ivermectin. Ivermectin became widely available for veterinary use in the mid-1980s, and is highly effective in killing microfilariae, as well as against other intestinal worms and the mites that cause mange. Common brands using ivermectin include Heartgard, Ivehart Plus and Tri-Heart Plus. Some breeds of dogs, especially collies, have a sensitivity to ivermectin, so owners of these identified breeds may want to consider milbemycin medications, which include Sentinel and Interceptor.
Injectable Treatment
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If a dog does develop heartworm disease, treatment is essential for long-term survival. The majority of heartworm cases are treated with an injectable medication to kill the adult heartworms. Currently, the only FDA approved injectable treatment for heartworm disease is Immiticide (an arensic-based drug), made by Merial. Killing the adult heartworms can cause embolisms in the lungs or heart as a result of the dead parasites entering the bloodstream. Once the adult heartworms are killed, the microfilariae are killed using one of the preventative methods listed above.
Oral Treatment
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Dogs with very low infections can sometimes be treated orally with ivermectin only. Ivermectin does not kill the adult heartworms, but does make them sterile and shortens the lifespan of the parasites. Treatment with oral invermectin only can take up to two years to clear the parasites, but is safer than injectable treatments and is better than no treatment at all. Using oral ivermectin for treating heartworm disease should only be done under the advice and close supervision of a veterinarian.
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