Source: Examiner.com, by Alexis Jenny

Dirofilaria immitis, also known as heartworm, is a condition in dogs caused by a parasite that uses mosquitoes as vectors. Heartworm can also affect cats and other animals.  This parasite attacks the heart tissue and can be fatal. There is treatment for heartworm, but the treatment is not a cure. Heartworm treatment can prolong the animal's life and make the animal more comfortable, but is time consuming and expensive. In comparison, preventative medicine is less expensive and easily administered.

In southern states and other warm climates, heartworm prevention should be given to pets throughout the year while mosquitoes are present. In northern states, like Pennsylvania, it is common practice to administer heartworm preventative 6 to 8 of the warmer months out of the year. This is because mosquitoes are rarely present during the winter months.

Heartworm preventative can be in the form of a chewable tablet, a pill, or a topical agent absorbed through the skin. The link below provides further information and comparable brand names.