Spring is the time of year when we inhale deeply and appreciate the beauty of new growth and abundance at the end of another long winter.
It's also the time of year when, SWAT!, mosquitoes start hatching and buzzing around, some of them carrying the deadly disease heartworm. Michigan is a heartworm endemic state, meaning much of our mosquito population is infected with the causative parasite, Dirofilaria immitis.
Infected mosquitoes can bite your dog or cat, injecting microscopic larvae into the bloodstream in the process. Each tiny worm will take about seven months to develop into an adult heartworm, which lives in the heart or major blood vessels, causing often irreversible damage. Most heartworm positive dogs are asymptomatic at first, sometimes for a year or more after infection, depending on the number of worms living in the heart. Ultimately, heartworm disease in dogs causes coughing, exercise intolerance, loss of appetite, weight loss and even death.
In cats, heartworm disease can be much more subtle. Many cats are asymptomatic, or have mild symptoms that can mimic feline asthma or allergy, which may include gagging, open mouth breathing after exercise, lethargy and weight loss. Testing in cats is also more difficult, as they usually carry a much lower worm burden. Fortunately, prevention is very effective.
Heartworm is not directly transmissable from animal to animal, as the microfilaria, or baby heartworms, need to go through a two-week life cycle in a mosquito before they become infective.However, if a pet in one area is heartworm positive, we can reasonably make the assumption that other mosquitoes in the area are infected.
Heartworm disease is easily prevented. Your first step is to take your pet to the veterinarian for a heartworm check, to make sure s/he is not already infected. If negative, your vet will likely prescribe a monthly heartworm prevention medication, which effectively "sweeps" your pets' bloodstream every 30 days, thereby preventing the worms from developing. If your pet is already positive, blood testing and chest xrays can help stage the disease, and decisions will be made about the best course of treatment.
In dogs, the disease is treated with a lumbar intramuscular injection series. In cats, there is no known treatment, other than surgical removal of the worms from the heart, a very risky procedure. In either case, the damage done to the heart and lungs can be permanent, so prevention is the safest (and cheapest) way to go.
To learn more, visit www.heartwormsociety.org.