Dogs become infested with heartworm when bitten by a mosquito carrying microscopic, immature heartworm larvae picked up from another dog. Once injected by a mosquito, the larvae take several months to migrate through the body and develop into adult heartworms - up to 14 inches long - that can fill the heart and block blood flow to the lungs. Early signs of the disease involve a drop in energy and an unproductive cough. If left untreated the worms can cause organ damage elsewhere in the body, and can eventually lead to heart failure and death.
A pet with heartworms can be treated, but the cure is difficult, expensive and sometimes fatal. This is one case where prevention is much, much better than the cure, which is why heartworm prevention is so important. The American Heartworm Society estimates that 27 million dogs are not on preventive medicine - leaving them at risk for this deadly disease, which is present in all states except Alaska. The disease is most prevalent in the Midwest and Gulf Coast states. However, at our practice in San Ramon we routinely treat three or four dogs a year who are infected with heartworms.
There is no legal requirement that dogs be given heartworm preventative medication as there is for dogs to receive triennial rabies immunization. Rabies immunization laws are intended to protect the health of the human population although the incidence of rabies in dogs in the United States is extremely low. However, the prevalence of heartworm disease among the canine population vastly exceeds that of rabies, and for our canine companions, prevention of this disease should be considered equally important.
Heartworm preventative medication generally costs no more than a few dollars a month. The monthly medication also prevents the major intestinal parasites, protecting your dog's digestive health as well as their heart. The intestinal parasites prevented by this medication are actually contagious to humans, so prevention by this single medication will benefit you as well as your dog. Despite the importance and ease of preventing these parasites it is estimated that most dogs do not receive their heartworm preventative tablet every month.
If your dog isn't on heartworm preventive, my hope is to raise your awareness of this deadly - yet easily prevented - disease. Have your dog checked by your veterinarian to make sure he or she isn't already carrying this infection, and if not, put your dog on heartworm preventive today. If you love your dog, protect him or her. It's a really small price to pay for the companionship of a pet.
--Dr. Franklin Utchen, shown with his dog Tory, has been practicing veterinary medicine in the San Ramon Valley since 1989 and currently co-owns Bishop Ranch Veterinary Center & Urgent Care. For questions or comments e-mail firstname.lastname@example.org.