Heartworm disease is a parasite that dogs can contract after being bitten by a mosquito. I have always found the method of transmission and the development of heartworm disease in dogs fascinating. Heartworm disease can be treated, but luckily there is a very easy way to prevent the condition by administering medication monthly.
The only way for a dog to contract heartworm disease is to be bitten by a mosquito. Five months after a mosquito bite, a worm migrates to the heart and can cause deadly consequences. A mosquito that bites an infected dog incubates the larval stage of the heartworm and then bites another dog. If the dog is not on preventative medication the worm goes into the tissue under the skin to develop. During its development over three to four months, the worm migrates through the tissue and somehow ends up in the pulmonary artery of the heart and in the right side of the heart.
The consequences of having these worms in the heart are severe. Early in the course of the disease there could be no signs of illness, but as the disease becomes chronic dogs can become weak, cough, spit up blood, and even develop heart failure.
There is a way to treat heartworm disease, but the therapy itself can be very toxic. Veterinarians inject a medication that slowly kills the worms. The drug is actually related to arsenic, which can have severe side effects. Generally a veterinarian will give two or three injections over the course of a month to your dog. It is very important to enforce strict rest for four to six weeks.
The good news is that there is an easy way to prevent heartworm disease. Administration of a medication monthly will kill the worms while they are still in the tissue under the skin. The worm never has a chance to migrate to the heart and cause damage. The medication is available in pill form or in a liquid that can be applied to the skin between the shoulder blades monthly. Your dog should have a yearly blood test, and if it is negative, monthly therapy should be administered year round. One benefit of giving the medication is that it also prevents many intestinal parasites that can be dangerous to dogs.
So heartworm disease is clearly a condition where prevention is so important. Because of the efficacy of today’s preventatives, no dog should ever develop heartworm disease. Luckily almost all of my patients take the monthly preventative, and I rarely see the disease.