Warmer temperatures and longer days are finally here! Sadly, so are unfriendly and potentially dangerous mosquitoes!

While most vets recommend keeping your dog on heartworm medication all year, if your dog has gone off heartworm prevention, there are some things you need to know.

First, let’s separate the facts from fiction

with the help of the American Heartworm Society!

Heartworm transmission infographic

Heartworm: The Facts
  • Heartworm (a type of roundworm or nematode) has been reported in all 50 states with greater risks in some states over others. According to the CAPCVet’s forecast for 2020, “we expect the prevalence to be much higher in areas along the Mississippi River, throughout the southern portions of the Midwest and along the Atlantic coast north into Virginia.”


Predicted Heartworm Cases Map 2020

  • It’s easier to prevent heartworm than treat it. Heartworm disease is a serious and potentially life-threatening disease.
  • While dogs can be effectively treated for heartworms, there is no known cure for felines (the treatment for dogs cannot be used in cats). Prevention is the only way to protect cats from heartworms. 
  • Dogs, cats and ferrets (and other wild mammals like wolves, coyotes, foxes, sea lions, seals and more) can only get infected through the bite of an infected mosquito.
  • Although it is very rare, humans can also get heartworm through the bite of an infected mosquito. 
  • Once a dog has been infected, it takes about 6-7 months for the larvae to mature into adult heartworms and for your dog to test positive (and why annual testing is so important). At that point, the worms begin to lodge in the:
    • Heart 
    • Lungs
    • Area Blood Vessels
  • Adult heartworms in dogs can: 
    • Grow up to 14” in length and
    • Live 5-7 years.
    • Cats: mature heartworms can live 2-4 years.
  • Dogs can be re-infected each mosquito season, and have up to 250 worms
  • Sadly, there are few-to-no symptoms of heartworm disease in the early stages. This makes prevention so important.  Even on a preventative, pets should be tested every year. If your dog has been off their preventative for 4-6 months, get them tested first to make sure they are not infected. If they test negative, you can safely resume their regular heartworm preventative. 
Heartworm: Fiction

Heartworm comes with its own set of myths that you might already know about. This helpful infographic from the American Heartworm Society gives details on the most popular tall tales about heartworm.

  • Dogs can’t catch heartworm directly from other dogs. It is spread by infected mosquitoes.
  • Heartworms can live any time of the year – and therefore infect our pets – even after summer is over.
  • Cats are susceptible to heartworm, and even one can be fatal. Remember, there’s no treatment for cats, so prevention is key!
  • Indoor-only pets, like other pets, require heartworm prevention too. Mosquitoes can travel into your home.
  • Pets should be tested even if they are on heartworm preventatives. Better safe than sorry for your beloved furry friends.
  • Prevention can be affordable, your pet’s health is what matters.
Heartworm: The NumbersHeartworm by the numbers infographic
  • The states with the highest cases of heartworm include Mississippi, Louisiana, Arkansas, Texas, Tennessee.
  • In Mississippi, more than one out of ten dogs tested, are heartworm positive
  • It is estimated that more than one million pets in the United States have heartworm.
  • There are over 22 different species of mosquitoes in Northern America can carry heartworms. They can also travel up to three miles, which puts many pets at risk of being infected.



Heartworm: The Symptoms

It takes one bite from an infected mosquito to give your dog, cat or ferret heartworm disease and without a heartworm preventative, they can be infected over and over each mosquito season. There is no “immunity” against reinfection outside of a medicinal preventative. 

By the time symptoms of heartworm disease appear, the parasites have already crowded the heart and lungs causing the infected canine to begin coughing. Other symptoms include:

  • Abnormal lung sounds
  • Being easily winded and unable to exercise as much as before 
  • Passing out (from loss of blood to the brain)
  • Retention of fluids
Heartworm: Prevention is the Cure

Finally, always work with your regular vet for year-round heartworm prevention and annual testing for your domestic pets. As the saying goes, “An ounce of prevention is worth a pound of cure.” 


 The Best Care for Your Best Friend!

Does your dog need some extra exercise? Or does your pet need some extra one-on-one attention with pet sitting? We will love and treat your pet like a member of our own family in the Davis, Woodland and Dixon areas of California!


Check out our Pet Care Services for your beloved pet and then reach out

to us via email or by calling 530-219-3656 today.

Additional Reading:

American Heartworm Society

Fetch by WebMD: Heartworms in Dogs: Facts and Myths

CAPCVet: Companion Animal Parasite Council

AVMA: Heartworm Disease


Image Credits (In Order of Appearance):

Image by Mylene2401 from Pixabay 

Infographic by American Heartworm Society

Map from HeartgardClinic.com by American Heartworm Society

Image by Mirko Sajkov from Pixabay 

Image by mathias70 from Pixabay 

Infographic by American Heartworm Society

Image by J C from Pixabay