Heartworm - A Serious Threat to Your Pet

Heartworm is a parasite that most dog owners and many cat owners have to be concerned about. The more you know, the better protected your pet can become.

Heartworm is an insidious disease that has spread to virtually all parts of the US and many parts of Canada since the early 1970s. It is spread only by mosquitoes; thus, areas heavily populated by these insects tend to have a greater incidence of heartworm disease.

Heartworm can strike both dogs and cats, although it is much more commonly seen in dogs. As its name implies, heartworm lives in the blood of a dog's or cat's heart and adjacent blood vessels. The adult heartworms living in the heart produce offspring, called microfilariae, which circulate in the infected animal's blood and can survive for about 2 years in the bloodstream.

When a mosquito "bites" an infected pet, it sucks out blood containing the microfilariae. After about two weeks in the mosquito, the microfilariae become infective larvae. This step is necessary for the transmission of heartworm. When the mosquito bites another pet, it picks up these larvae and can transmit the infection to other dogs and cats.

Heartworm Lifecycle 

Over time, the presence of the adult worms in the heart and pulmonary arteries causes an inflammation and thickening of the walls of the blood vessels which leads to an increase in blood pressure and in the hearts effort to push the blood through these vessels. As a consequence, the dog may develop heart failure, which can eventually lead to his death. Clinical symptoms usually appear only when the disease has reached a very severe stage (usually 3 to 5 years from infection). First signs consist of sporadic coughing and tiredness; as time passes, cough becomes chronic and is accompanied by difficult respiration, particularly during and after exercise. In advanced cases, the dog may collapse after even light physical exertion. Most dogs eventually develop congestive heart failure.

 Parasitic Heartworm Infected Heart

Treatment of heartworm infection is a long and risky process. Dying heartworms as well as their larvae may cause shock and embolism. During therapy, dogs have to be strictly controlled for side effects, and their activity restricted for a few weeks. However, in advanced cases, health will not be restored even after effective treatment.

For all these reasons it is now clear why prevention is so important.

In contrast to therapy for the disease, heartworm prevention is safe, easy and effective. Before prophylactic treatment is started, dogs should be tested for heartworm infection. A small amount of blood is all that's necessary for a preliminary heartworm screening test that is very accurate in detecting the presence of heartworm. Those found to be infected have to be treated against adults and microfilariae, before a prevention program is started.

Preventatives are now recommended monthly and year round to prevent heartworm.

Most of the preventatives are also effective against the two most common intestinal

parasites, which can be contagious to humans. Treating your dog or cat to these preventatives ensures complete protection of your pet.

Although heartworm is seen less frequently in cats, the disease poses a much greater danger. The outcome is often fatal. There currently are no drugs approved for fighting heartworm in cats. There are no consistent clinical signs of heartworm in cats. Common clues include coughing and rapid breathing. Other signs include weight loss and vomiting. However, all of these signs are also common in other diseases. Diagnosis is difficult for veterinarians and may include outside laboratory tests, radiographs, and ultrasound studies.

The good news is that there are heartworm prevention drugs available for cats. If you live in a heartworm infested area, or plan on visiting a heartworm area with your cat, your veterinarian can prescribe a preventive medication. These drugs are given once monthly and are very effective in cats and kittens and should be given to all cats with outdoor exposure.

There are several excellent, highly effective products to prevent heartworm disease in your pet. Heartworm disease is a serious threat to the health of your dog or cat. To protect your pet from heartworm disease, give a product such as Heartgard once a month year around or as directed by your veterinarian. Dogs 6 months of age and older should be tested for, and be negative for heartworm disease prior to being put on a preventative program. Dogs should be retested annually.

The heartworm preventatives are available only through a licensed veterinarian, so make an appointment to see your veterinarian today.