Heartworm Disease in Dogs

Most people have heard of heartworms, but fewer know that dogs are at serious risk of contracting heartworm disease in any area where mosquitos are present. Insidious parasites that nest in dogs’ hearts, lungs and surrounding blood vessels, heartworms are easy to prevent, but difficult and costly to cure. For this reason, pet owners should protect their dogs against heartworms in any area where mosquito bites are even a remote possibility.
 
Dogs only contract heartworms in one way: through the bite of an infected mosquito. This is because adult heartworms thriving in an infected animal produce baby worms, known as microfilaria, which circulate throughout the bloodstream. When a mosquito bites an infected pet, it picks up the microfilaria, which develop into larvae within the mosquito. When the infected mosquito bites another animal a few weeks later, it passes on these larvae, which mature into adult heartworms and continue the lifecycle. It only takes one bite and, about six months later, the larvae mature into adult heartworms within a dog. Pets with untreated heartworms may harbor several hundred of the parasites, which leave lasting damage to the heart, lungs, arteries and other organs even after they’ve been treated.
 
The good news is that heartworms cannot be passed from dogs to humans or other pets. The parasite is only transmitted through mosquitos, and typically affects only dogs, cats and several other mammals. The bad news is that, once infected, a dog needs serious and costly treatments to rid him of the parasites. Symptoms of heartworm disease may take some time to appear, but as the worms begin crowding a dog’s heart and lungs, he may develop a cough, intolerance to exercise, trouble breathing and fatigue. Left untreated, most heartworm infestations are fatal. Fortunately, heartworm disease is easily preventable. Chewable pills, monthly topicals and six-month injections all exist to arm your pet against mosquito bites and heartworms. A year’s supply of heartworm medication ranges in cost from around $35 to $80, depending on your dog’s weight— many times less than the cost of curing an infected pet. While you may be tempted to stop treatment during the colder months of the year, when mosquitos are inactive, the American Heartworm Society recommends using year-round heartworm prevention. Owners may forget a monthly dose, which is typically a non-event if your dog is being treated consistently, and many heartworm pills also treat for other parasites such as roundworms, whipworms and tapeworms that are present year-round.
 
In the case that your dog does become infected with heartworms or you purchase a heartworm-positive pet, the disease is treatable. An injectable product called Immiticide is used to wipe out adult heartworms in the blood vessels. However, as the worms die, they break down and can block a dog’s pulmonary vessels, making it crucial for dogs to keep quiet for several months during and after treatment. Remember, even if your dog has survived heartworms once, the parasite can come back, making heartworm prevention a no-brainer for any owner.