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An Ounce of Prevention: The Facts on Heartworm Disease

by Stacy Conroy

Ten-inch worms that set up housekeeping in the arteries of the heart and lungs cause heartworm disease in dogs, and it strikes many beloved family pets in our area each year. The disease is spread by mosquitoes, and no dog is out of its reach in the U.S. Though the heaviest infection rates are along the Mississippi River and its tributaries, heartworm is found in all 50 states. Southeastern Wisconsin is a high infection area. Infected animals can be treated and successfully overcome the infestation. However, treatment of the disease can be painful and drawn out over a long period of time with persistent symptoms causing additional discomfort. Once infected, the blood of a dog with heartworm will not test positive for worms until six to seven months after initial exposure. The heartworm is detected by analyzing blood for an antigen from the adult female worm. Though rare, a false negative can result from the presence of only the male worms in a dog’s system. X-rays of the heart and lungs are the best tools available to evaluate the severity of the disease. Typical signs of the disease in various stages seen on radiographs are enlargement of the right side of the heart, main pulmonary artery, and pulmonary arteries in the lobes of the lung. Inflammation in the lung tissue that surrounds the pulmonary arteries is also an indicator. Dogs with higher numbers of worms are usually discovered to have more severe heart and lung changes. Later in the disease, if left untreated, the heart may enlarge, become overworked, and weaken, leading to congestive heart failure. Untreated heartworm disease can last years in infected dogs and clinical signs may not show up for a year or more after contracting the disease. The first symptom of mild heartworm disease is a cough. Moderate cases experience exercise intolerance, abnormal heart and lung sounds, and severe cases involve difficulty breathing, enlarged liver, and eventually death. Jodie Gruenstern, DVM, of the Animal Doctor clinic in Muskego, strongly suggests that heartworm testing and preventative medication are more safe for dogs and economical for caregivers than the conventional treatments currently available for the disease. “Once a dog is diagnosed with heartworms they receive a series of injections of a drug called Immiticide in the back muscles which causes a lot of pain,” said Gruenstern. “Another side effect is the possibility of an abscess at the injection site and additional medication is given to slowly kill of the microfilariae in the blood,” she continued. Gruenstern uses Interceptor as a heartworm preventative medication and recommends her clients use it year round. Even though mosquitoes are only out part of the year, the medication works backwards to kill off any microfilariae that may be in the blood from a bite in the previous month. “People tend to forget to give the pills if they only administer it a few months out of the year. Interceptor kills other parasites such as whipworms, which Heartgard doesn’t do,” said Gruenstern. Gruenstern says she has many holistically minded clients who try to care for their dogs as naturally as they can, avoiding prescription drugs as much as possible. Though she is a holistically trained vet, she feels that the benefits of using a heartworm preventative medication far outweigh the risks of relying on a healthy dog’s immune system to fight off parasites as serious as heartworms. “Some people may think that because the medication is given monthly that it stays in the dog’s system for a month, when actually it is only in their body for a day,” she concluded. The Animal Doctor clinic does offer an herbal detox formula for use before and after the heartworm pills are administered at home. This can help the liver process the medication more quickly. Dogs who are outdoors at parks and who live in homes or camp near lakes and rivers are most at risk of being bitten, but even city dogs get heartworm. Just being out in the yard puts a dog at risk. According to the Heartgard product web site, 369 clinics in Wisconsin reported 1,362 heartworm positive dogs from January 1, 2001 to December 31, 2001. Though the numbers of infected dogs in Milwaukee, Waukesha, and Racine counties was well over 100 cases per county, more than any other counties, this is likely due to the high concentration of animals per household compared to less populated counties. To read more about the heartworm, the disease it causes, and how to protect your pet, visit the American Heartworm Society at www.heartwormsociety.org.
by Stacy Conroy