Heartworm disease is a serious and potentially fatal condition affecting both dogs and cats. It's caused by worms living in the arteries of the lungs and sometimes in the right side of the heart.
The disease starts with an adult female heartworm releasing baby worms called microfilariae into an animal's bloodstream. As can be see in the Heartworm Life Cycle image by the American Heartworm Society, when a mosquito bites that animal, it becomes infected with microfilariae.
After two weeks in the mosquito, the microfilariae has developed and can be passed on to other animals when mosquitos bite them. It then takes about 6 months for the infective larvae to mature into adult worms. In dogs, the worms may live for up to 7 years.
An interesting fact is that the microfilariae cannot mature into adult heartworms without first passing through a mosquito (so they need that dreaded little bug). In addition, they really do look like little angel hair pasta pieces.
For both dogs and cats, symptoms of heartworm disease may not be recognized initially as it can take months for the heartworms to develop. Dogs eventually show signs, including a mild, persistent cough, fatigue, reduced appetite and weight loss. Cats show many nonspecific symptoms making the disease difficult to diagnose. Such symptoms include vomiting, gagging, difficulty or rapid breathing, lethargy and weight loss.
How do I prevent heartworm disease in my pets?
There are a variety of options for preventing heartworm infection in both dogs and cats, including daily and monthly tablets and chewables, monthly topicals and a six-month injectable product available only for dogs. These medications interrupt heartworm development before adult worms reach the lungs and cause disease; in other words, the worm never gets to grow-up.
All of these methods are extremely effective and, when administered properly on a timely schedule, heartworm infection can be prevented. And, as we all know, prevention is best.
~ Dr. Shae Martin, DVM