Lucky Chance Rescue

Learn About Heartworms & Prevention

Heartworm disease is a serious and potentially fatal disease in pets. It is caused by foot-long worms (heartworms) that live in the heart, lungs and associated blood vessels of affected pets, causing severe lung disease, heart failure and damage to other organs in the body.


Heartworm Prevention for Dogs

Heartworm prevention for dogs is an important concern for every pet owner. Prevention is an important part of providing essential care, and heartworm disease prevention for dogs is something every owner can do. Consider this:

  • Heartworms are spread by mosquitoes
  • Dogs don’t just need prevention during warm-weather months. Heartworm preventives work by treating heartworms that already infected the pet within the past month or longer; meanwhile, preventives need to be given on time, every time to be effective. That’s why the American Heartworm Society recommends year-round heartworm prevention for pets.
  • The American Heartworm Society estimates that more than a million dogs in the U.S. have heartworm disease—and heartworm disease can be fatal.
  • Cats and ferrets can also get heartworm disease.
  • Heartworm preventives are safe, relatively inexpensive and easy to give, but if a dog becomes infected, heartworm treatment can be costly and difficult, requiring multiple veterinary visits and months of exercise restriction.
  • There’s no such thing as a “natural” heartworm preventives.

What are the signs of heartworm disease in dogs?

In the early stages of the disease, many dogs show few symptoms or no symptoms at all. The longer the infection persists, the more likely symptoms will develop. Active dogs, dogs heavily infected with heartworms, or those with other health problems often show pronounced clinical signs.  Signs of heartworm disease may include a mild persistent cough, reluctance to exercise, fatigue after moderate activity, decreased appetite, and weight loss. As heartworm disease progresses, pets may develop heart failure and the appearance of a swollen belly due to excess fluid in the abdomen. Dogs with large numbers of heartworms can develop a sudden blockages of blood flow within the heart leading to a life-threatening form of cardiovascular collapse. This is called caval syndrome, and is marked by a sudden onset of labored breathing, pale gums, and dark bloody or coffee-colored urine. Without prompt surgical removal of the heartworm blockage, few dogs survive.

American Heartworm Society
Heartworm Prevention

You Can Prevent Heartworms!


Have your veterinarian test your dog each year for heartworm infection. It takes roughly 6 months for an infection to be detected with a standard heartworm test, so if your dog becomes infected, this schedule helps ensure early diagnosis and treatment..


Skip testing just because your dog is on year-round heartworm prevention. While this will likely keep him or her heartworm-free, if you miss a dose, are late with it—or your dog spits out or rubs off the medication—it could create an infection opportunity


Give your dog his or her heartworm preventive on time, every time. Whether you give a monthly pill or spot-on medication—or you visit your veterinarian for a semi-annual injection—being consistent is essential.


Stop prevention just because you haven’t seen a mosquito lately. Heartworm preventives work retroactively, eliminating new infections that were transmitted months earlier. Rather than guessing at when it might be “safe,” keep your pet on prevention year-round.


Make sure the product you rely on actually is a heartworm preventive. With so many parasite protection products on the market, it’s easy to get confused. Far too many people assume their flea and tick product is protecting their dog from heartworms when it isn’t.


Forget that many heartworm pills and spot-on products protect against other parasites. Some protect pets from intestinal worms; others also protect against fleas and certain ticks and mites. Talk to your veterinarian about what product offers the protection your dog needs.

Lucky Chance Rescue

Saving Pets Is What We Do!

Helpful Information

We are committed to the ethical treatment of animals, through pet adoption, promoting spay and neuter to end overpopulation and unwanted animals, reuniting missing pets with their owners and educating pet owners on the importance of veterinary care. Below you find great information to help you on your journey of being a successful and happy pet owner.