Heartworm: What it is and Why it is Vital to Give Your Pet Heartworm Preventative

What you need to know about Heartworm:

  • Heartworms can infect both dogs and cats.
  • The disease is transmitted when an animal is bitten by an infected mosquito. 
  • Heartworm disease has been diagnosed in every state, though it is more prevalent in states like Georgia, where the weather stays relatively warm all year.  Because mosquitos can come into your home, your pet is at risk even if it is an "indoor" pet.  


  • According to information from the University of Georgia College of Agricultural and Environmental Sciences, "there's almost 100% chance that a dog living in Georgia will have the disease by age 5 if its owners don't give it a monthly preventative."
  • Because dogs are a natural host for heartworms, the heartworms actually mate and produce offspring inside the dog.  This means their numbers can increase and, according to the American Heartworm Society, dogs have been known to have hundreds of heartworms in their bodies.
  •  Adult heartworms live in the heart, lungs and associated blood vessels of affected pets, causing damage to the heart and other organs, and compromising the animal's quality of life. 
  • In dogs, heartworm disease is FATAL IF LEFT UNDIAGNOSED AND UNTREATED, but 100%  PREVENTABLE when your pet is protected year round with a monthly preventative.
  • While it is possible to treat heartworm disease in dogs, prevention is much safer and easier on your pet. The currently recommended treatment protocol takes 3 to 4 months, during which time, the animal must be kept inactive -- think "crated" -- except for necessary trips outside to potty.  And the treatment is very expensive, usually between $500 to $1,800! 
  • All dogs should be tested annually for heartworm, even if they are on heartworm protection year-round, to ensure that the prevention program is working.  If one dose is missed, it can leave the animal unprotected.  And, even if you administer as prescribed, a pill can be spit out, and a topical application can be rubbed off. 


  • Although cats are also susceptible to heartworms, cats are not a natural host.  For this reason, heartworms do not typically survive to the adult stage where they are capable of reproducing; thus, there are usually fewer worms.  
  • Because there are fewer heartworms, cats are less likely to display symptoms of heartworm disease, and it often goes undetected unless a heartworm test is performed. However, it can still do damage and affect a cat's quality of life due to a condition known as "heartworm associated respiratory disease".
  • Unfortunately, according to the America Heartworm Society, there is no approved drug therapy for heartworm infection in cats.  While cats with heartworm can often be helped with excellent, ongoing veterinary care, the only way to protect them from the effects of heartworm is prevention.

Other resources you may find helpful:

Heartworm and Flea/Tick Preventatives Available at Vaccination Cllinics

American Heartworm Society: Heartworms in Dogs

American Heartworm Society: Heartworm in Cats

What is Heartworm Disease and How is it Treated? (article by Dr. Mavis McCormick-Rantze, Lanier Animal Hospital. Sugar Hill, GA)

Flea and Heartworm Prevention for Your Pets