You may have seen ads about protecting your dog against heartworms, and wondered what a heartworm was. How does a dog get infected by heartworms, and why do they make it so sick? There are treatments for heartworms your veterinarian can administer; however, it is of course better to prevent the infection in the first place. Ask your veterinarian how generic Heartgard can help your pet avoid this debilitating parasite.
The heartworm is a parasitic worm (Dirofilaria immitis), from the phylum nematoda or round worms. A multi-celled animal with a rather complex reproductive and life cycle which involves an intermediary host, the mosquito, and unfortunately, your dog or sometimes other mammals, including you. The larval worms, or microfilaria, have developed inside a mosquito that then bites your dog. Inside your pet over a period of six to seven months, they undergo a series of molts as they migrate from just under the skin to congregate in the pulmonary vasculature as they reach adult stage and begin to reproduce. An adult female (which can reach 33 cm long) delivers live microfilaria into the bloodstream of the host. These larvae circulate in the blood until they are picked up by another mosquito, and so on. Heartworm infections have been reported throughout North America.
Mosquitoes are the agent that spreads these worms from mosquito to dog to mosquito and so on. This is the reason why heartworms infections are seasonal in most areas - the microfilaria require two to six weeks (depending on the temperature) inside the mosquito to reach the infective stage. At temperatures below 57 degrees Fahrenheit, the process halts entirely.
Your dog will have no symptoms in the months leading to the adult stage (prepatent period). It is when the worms reach adult stage and congregate in the branches of the pulmonary artery that symptoms can appear and range from none at all to heart failure and death. This heart failure happens as the right ventricle fails due to mechanical obstruction by worms, leading to the signs and symptoms of congestive heart failure and fluid overload.
Suspect heartworms when your dog has a significant cough, and he becomes exhausted with minimal exercise. These symptoms don't appear until the infestation is quite significant. It is important to see a veterinarian for a definitive diagnosis right away if you suspect heartworms.
The only way to cure a heartworm infestation is to kill all the adult worms. Your vet will usually use arsenicals (medicines containing arsenic) to achieve this. The patient's care and progress must be followed closely - serious complications, such as a pulmonary embolus, can arise from the death of the adult worms in the pulmonary circulation. The medicine is highly toxic and must be administered by a veterinarian.
You can see that in the case of these worms, an "ounce of prevention" is indeed "worth a pound of cure." The approaches to preventing an infection fall into two basic categories: stop the mosquito from biting the dog, or stop the microfilaria from maturing into adult worms. Ivermectin, (which is the generic name for Heartgard) is one of the drugs approved to prevent the maturation of heartworms.
Now you don't have to worry as much about canine heartworms. Take good care of that great family pet and talk to your veterinarian about protecting him with generic Heartgard.