The thought of a worm living inside the body is already unsavory, but even more so when the worms are living in one of the body’s most important organs… the heart! One of the most horrible parasites that can infect our pets is heartworm, or Dirofilaria immitis. More common in dogs than in cats, these wriggly creatures spend their adult lives in the heart and major vessels of the host animal, interfering with the ability of the heart to pump blood, and eventually causing heart failure. The female worm releases her young, called microfilariae into the bloodstream. Heartworm infection is spread by mosquitoes from animal to animal. The mosquito also acts as a vehicle for the larvae while it develops further. When the mosquito bites the next pet, it infects it with the heartworm larvae. Thus, the cycle starts again in the new host.
Signs of heartworm disease are similar to signs of heart disease. Affected dogs and cats may exhibit coughing, weakness, lethargy, exercise intolerance and reduced appetite. In severe cases, heart failure may result, manifesting in collapse or sudden death.
Treatment for heartworm in dogs when adult worms are present involves repeated injections of a drug that kills the worms. There is a risk associated with treatment, in that the dead worms may become stuck in the major blood vessels, causing a blockage to blood flow. Even if the adult worms are successfully eradicated, the animal may suffer ongoing heart disease and may require long term medication for this. Treatment of infection with the larval stages is easier, and involves a few doses of monthly injections or tablets. In cats, treatment of heartworm is much more dangerous and there are currently no drugs that are approved for this purpose.
There is, however, some good news regarding heartworm disease. It is very easy to prevent! There are a whole range of options that make heartworm prevention feasible and affordable. These options include 6-monthly injections administered by your vet, and monthly tablets or topical treatments, as well as daily tablets that you can administer at home. With so many easy to administer options for prevention, there is no excuse to place your pets at risk of heartworm infection!