The Lord God Made Them All - Heartworm Disease

Ah, the dog days of summer. Your pet is absolutely delighted with the prospect of being able to romp around the yard sniffing out his favorite squirrel. Flowers are blooming, bees are buzzing, misquitos and ticks are biting and your dog and cat have a chance of getting heartworm disease. Hey, what happened to our picture of an idyllic summer?

I see far too many dogs down here in southern Illinois suffering from heartworm disease. Make a commitment today to start a heartworm prevention program for your pet.

What is Heartworm disease? According to the American Heartworm Association: Heartworms can only be transmitted from animal to animal by mosquitoes. When a mosquito bites an infected animal, young heartworms called microfilariae enter into that mosquito's system. Within two weeks, the microfilariae develop into infective larvae inside the mosquito; these infective larvae can be transmitted to another animal when this mosquito takes its next blood meal. The infective larvae mature into adult heartworms in approximately six months. During the first three months, the larvae migrate through the animal's body, eventually reaching the blood vessels of the lungs. During the last three months, the immature worms continue to develop and grow to adults, with females growing to lengths of up to 14 inches. The worms damage the blood vessels, and reduce the heart's pumping ability, resulting in severe lung and heart disease. When the animal shows signs of illness due to adult heartworm infection, it is called heartworm disease. If adult worms (5-7 months post-infection) of both sexes are present, they will mate and produce new microfilariae. The microfilariae can cause the animal's immune system to mount a reaction; this immune reaction can actually cause damage to other organs. This life cycle continues when a mosquito bites the infected animal and becomes infected by the microfilariae. After development of the microfilariae to infective larvae within the mosquito (10 days to 2 weeks later) the infective heartworm larvae are capable of infecting another animal. Adult heartworms can survive for 5 to 7 years in dogs and several months to years in cats.

Can it be prevented or treated? Heartworm infection is almost 100% preventable in dogs and cats. There are several FDA-approved heartworm preventives available in a variety of formulations. Your veterinarian can recommend the best method of prevention based upon your pet's risk factors and lifestyle. Of course, you have to remember to give your pet the preventive in order for it to work! The preventives do not kill adult heartworms, and will not eliminate heartworm infection or prevent signs of heartworm disease if adults are present in the pet's body.

How do I know if my pet has heartworms? A blood test for existing heartworm infection is recommended before beginning a prevention program to assess the pet's current heartworm status. Because it is more difficult to detect heartworms in cats, additional testing may be necessary to make sure the cat is not infected. Testing must then be repeated at appropriate intervals. The next test should be performed about 6 months after starting the preventive treatment, to confirm that your pet was not infected prior to beginning prevention (remember, tests only detect adult worms). Heartworm tests should be performed annually to ensure that your pet doesn't subsequently become infected with the disease and to ensure the appropriate amount of medication is being prescribed and administered. There have been reports of pets developing heartworm infection despite year-round treatment with a heartworm preventive, so having your pet tested regularly is the best way to keep them protected.