Stop heartworm before it starts

Nadine Lober

Heartworm is a parasitic disease that can affect any dog regardless of age, sex or habitat. It is spread by mosquitoes and is found, now, in virtually all parts of the United States. It is more prevalent along the Atlantic and Gulf coasts and the Ohio and Mississippi river basins. But there are now pockets of infection where the disease had previously been rare. And cases in the Denver area are the reason for instituting the preventative medication in the mountains.The actual disease is related to the number of worms infecting dogs. The adult worm lives in the blood of a dog’s heart and adjacent vessels and can grow to four or twelve inches, mature one year after infection and live for five to seven years. The adult heartworms living in the heart produce offspring, known as microfilariae, which circulate in the animal’s blood. When a female mosquito bites an infected animal, it sucks out the blood containing the microfilariae. When the mosquito bites another pet, the infected larvae are transmitted and the cycle begins again. Outdoor dogs are more likely to be infected than indoor dogs between the ages of 3 and 8. Large dogs are more susceptible than small dogs and thickness of coat does not appear to affect the probability of infection. Once a dog has been infected by a mosquito, the larva migrates through body tissues for the next 100 days. At that time, young adult heartworms enter the blood system and travel to the lungs. Once the adult heartworms have made their way to the pulmonary arteries, damage to the lining of the vessels begins. The organs harmed are the heart, lungs, and kidneys.Clinical signs vary from minimal coughing to more severe coughing, fatigue, listlessness, weight loss, rough hair coat and listlessness associated with lung damage. In severe cases, dog will not want to exercise at all. Heartworm can be detected with simple blood test. If this is positive, owners can then test further for the presence of an adult heartworm in the blood.A blood test must be performed before starting an adult dog on the preventative medication, to insure there’s no larvae in the blood. There a few such medications on the market, such as Heartguard (now called Tri-heart); Interceptor, which also controls some other less harmful worms (parasites); Revolution, which controls other worms and fleas and ticks as well; and an injectable medication that lasts 6 months. If your dog tests positive for the microfilaria or the adult worm, a veterinarian will begin treatment, which varies according to the type of infection. Most patients are hospitalized during treatment to kill the adult worm. The medication used is strong and the effect of killing off the worms can potentially cause problems in the lungs. The circulating worms are usually killed 4 to 6 weeks after getting rid of the adults.Heartworm can be a severe disease. But there have only been a few cases in the Vail Valley and those have mostly been in dogs who have traveled from other places. Remember, a simple blood test can detect the nasty creatures and help your know your pet’s status.

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