The mosquitoes also have something for our dogs and cats: heartworm disease. Interestingly, people can’t protect themselves against mosquito-borne diseases as efficiently as you can protect your dog against heartworm. Canine heartworm preventives really are effective; they can save your dog’s life. But you have to use one in order for it to work. According to a 2001 Gallop survey of 18,000 veterinary clinics across America, only 55 percent of the dogs were protected by a heartworm preventive. It’s astounding that nearly half the dogs had no protection against a potentially fatal but totally preventable disease.
Infected mosquitoes transmit a tiny parasite (Dirofilaria immitis) that is actually the larval stage of a worm. Once settling inside a dog, the parasite (which was minuscule enough to reside within the mouth parts of a mosquito) develops into a six- to 12-inch long worm that ultimately sets up shop in the heart and pulmonary arteries. Imagine a strand of spaghetti wound within the arteries of your dog’s lungs.
Most healthy dogs can deal with one single adult heartworm, or perhaps even a few. The problem is that most unprotected dogs are plagued with many of these worms. It’s not unheard of for dogs to have infestations of more than 100 worms, living and thriving for the duration of their natural five to seven year lives. With perhaps dozens of 12-inch long worms living in a dog’s pulmonary arteries, it’s no wonder the resulting signs include coughing, intolerance to exercise, impact on other vital organs and eventually, fatal congestive heart failure.
Dr. Sheldon Rubin, Chicago-based secretary-treasurer of the American Heartworm Society says, "No dog has to suffer heartworm disease." Dr. Jorge Guerrero is a board member of the American Heartworm Society. He goes a step further: "It’s absolutely shocking to still have to treat heartworm so often."
But the news gets worse. Of those who do treat their pets for heartworm, up to a third sometimes forget to give the medication (it’s just one dose per month). Owner compliance is a huge issue throughout veterinary medicine, but if you forget to dose your dog a few months in a row, your pooch might get heartworm.
This problem led one veterinary pharmaceutical company to develop a six-month injectable called ProHeart 6. Visit your vet as needed, once or twice a year, and your dog is a covered – no monthly pill to remember.
Some people have some concerns about alleged side effects or adverse reactions from ProHeart 6. But in many parts of the country, the odds of a dog becoming infected with potentially fatal heartworm when people forget to give him the monthly pill are far higher than the odds of the dog getting sick from ProHeart 6. Rubin says, "People rationalize, ‘It’s never going to happen to my dog." But heartworm is happening, and it’s happening to somebody’s dog. Of course, it can be your dog. The only way to ensure that it doesn’t, is to use a preventive."
The American Heartworm Society, a not-for-profit organization that furthers research and prevention of heartworm, is hosting a State of the Heartworm Symposium at the Conference of the American Veterinary Medical Association. One of the things they will be discussing is the new finding that there are specific bacteria inside the heartworms themselves that help the parasites to survive. Guerrero hopes the bacteria study will also assist in diagnosing heartworm in cats. While there is a test to determine if a dog has heartworm, there is no similar test for cats. Guerrero thinks that a test to determine the presence of these bacteria could possibly be created for cats.
Guerrero says canine heartworm can actually occur in people, and new research on this subject will also be presented at the symposium. He says that in humans, heartworm produces a dead end infection in the lungs, but it’s often misdiagnosed as a tumor in a lung.
The bottom line is that heartworm in dogs and cats is easy to prevent. Guerrero says, "You’re doing your dog no favor by not using a preventive. It doesn’t matter where you live – if there are mosquitoes, there may be heartworm."