What Are Heartworms?

• Heartworms are parasitic worms that mature in animals, but are originally passed as larvae through a mosquito bite. The worms continue to grow from 7 to 11 inches in the animal's body and reside in the heart or lungs of an infected animal. According to Bayer Advanced, there are more than 200 species of mosquito in the United States and 77 are in Florida alone. The Department of Health and Human Services, Centers for Disease Control states that mosquitoes are found worldwide except for Antarctica. Dog owners should administer heartworm prevention through the entire year to lower the chances of infection. Areas that experience freezing temperatures during the winter might be able to stop the preventative for a few months, but it is not recommended.
  
  

Heartworms in Animals

• A mosquito that feeds on the blood of an infected animal draws in the larvae of the worm. The worm larva is then passed on as the mosquito bites into its next meal. The mosquito can pass many larvae with one bite. The larva lives in the bloodstream of the newly infected animal until it matures into a worm and makes a home in the animal's heart and lungs. The worms grow, create stress on the animal's heart and lungs and eventually will cause blockages in the animal's blood flow.
  
  

Symptoms, Detection, Prevention

• Dogs with heartworms may show signs of fatigue, lose their appetite, lose weight and have trouble breathing. The symptoms may also be signs of other illnesses. Heartworms can be detected with a blood test or X-ray of the animal. Prevention of heartworms includes medicines such as Heartgard, Iverhart Max, Iverhart Plus and Interceptor. The preventatives are designed to attack the larva in the bloodstream prior to maturity. These preventive medicines will not kill an adult heartworm; for that, a compound must be administered to the animal.
  
  

Treatment for Dogs

• According to the American Heartworm Society, adult heartworms in dogs are killed using a drug called an adulticide, which is injected into the muscle through a series of treatments. The adult worms cannot all be killed at the same time. The dead bodies of the worms, if numerous, will block blood flow and cause heart failure. Dogs that do go through treatment must have follow-up visits to make sure that all of the worms were killed.