Heartworms are parasites that attack an animal's heart and cause congenital heart problems if not detected. They are transmitted from animal to animal, after one is bit by an infected mosquito. Heartworms normally live in the right ventricle of the heart and in the nearby blood vessels.

Adult male and female worms that are living in your pet's heart produce millions of baby parasites that circulate through your pet's body. When a mosquito bites an animal with heartworms, it sucks up the baby worms and transmits them to the next animal it bites. Those worms now live in the heart of the newly infected animal, where they become adults and begin to reproduce.

When the baby worms are transmitted into the new animal, it takes approximately 6-7 months for them to become reproducing adult worms. They are only detectable when they are adults, so an animal needs to be infected for at least 6 months before it can be diagnosed through blood tests or X-rays.

Since heartworms can be spread easily from animal to animal, it is important to use preventative measures to protect your pet. Veterinarians recommend heartworm prevention for all dogs and as knowledge on heartworms in cats is increasing, prevention for cats is also becoming common.

In order to protect your pets from heartworm disease:

• Make sure you have your pet tested for heartworms before you begin to give them preventatives- unless they are less than 7 months old. If your pet is over 7 months and is started on preventative heartworm medication without initial testing, they are at risk for serious reactions to the medication.

• Puppies should be given a heartworm preventative by the time they are 8 weeks old.

• Puppies should be tested once they are 7 months old even if they are taking preventative medication.

• Dogs should be tested on a regular basis. Testing should be done every 2-3 years if the dog is regularly given the preventative medication, and every year if any doses of the medication were missed.

• In cats, one heartworm can cause sudden death, but it is difficult to test in cats. You can start the preventative medication without an initial test.

• Cats do not display the same symptoms as dogs. The symptoms in cats are similar to those of other common cat diseases. It is important to remember the possibility that such symptoms can be because of heartworm.

It is important to protect your pets from heartworms because it can be a fatal disease. However, if they are detected in your dog, there are curable treatments to use. A series of injections cause the adult heartworms living in the heart to die. The worms then continually break up into smaller pieces until they are small enough for the body to absorb. While this is happening, the dog's heart is working harder than usual, so it is important that the dog does not do any strenuous exercise for 5 weeks. After 5 weeks, the dog is given a one day treatment to rid its body of the baby worms. Be sure that your dog receives a follow up test 6 months after the treatment to ensure that the heartworms are gone. There are currently no heartworm treatments for cats yet. The best way to treat a cat infected with heartworms is to begin using preventative medications to help alleviate your cat's symptoms.