This problem is caused by a worm that lives in the heart. The worm is spread by mosquitoes when it is very small and once introduced into the body of the dog or cat by the mosquito, it grows into an adult. The worm(s) presence causes irritation and can cause an allergic-like reaction. Most individuals with heartworms will develop heart and lung disease. These diseases can be life threatening. Although the disease can be prevented easily by a once a month medication, once the disease is present, it is very serious for the pet. The treatment to kill the worm is potentially very hard on the pet as well. Although cats are much less likely to develop heartworm infestation, even if bitten by an infected mosquito, they tend to have more dramatic and more serious problems, and diagnosing the disease in cats can be very difficult.

Although many areas of the United States and even California have been hotbeds of infection with heartworm, this area has always been one where we felt the disease did not exist, but lately, several dogs have been diagnosed with the disease that had to have been exposed locally. Because of this, we are recommending testing and the use of preventative medication in your pets, even if they do not travel out of this area. The risk may not be high that your pet will be exposed, but if it is, the consequences can be serious. If you do take your pet(s) to other areas, especially mountain areas or Central or Northern California, it is especially important to protect them from this disease causing parasite.

The test is a blood test that looks for antibodies to the presence of the heartworm. Once your pet is exposed to heartworm, it can take several months for the test to show positive, even though worms are present. If your pet has potentially been exposed to heartworm by having been in a high risk heartworm area, it may be necessary to wait awhile to test them or may require repeating a test several months later to be on the safe side.Testing for microfilaria as well can help pick up some of these infections. It is important to test your pet prior to starting heartworm medications because if your pet already has the parasite, the preventative medication will not kill the existing worms and they will continue to cause heart and lung damage until properly treated.

While it is easy to prevent heartworms in our pets, treating them is expensive and risky, as the treatments are often very hard on the pet, and any heart or lung damage already present will be permanent.