Is Heartworm Contagious in Dogs & Cats?

This post is written by our holistic veterinarian at "I and love and you", Dr. Angie Krause, DVM, CVA, CCRT

Heartworm disease is common in the US, and regularly affects dogs and less often cats. Your dog or cat can be infected by a mosquito bite. When the mosquito bites your pet, immature heartworms living in the mosquito make their way into your pet’s bloodstream. In 6-12 months, the adult heartworms begin reproducing while residing in your pet’s heart and lungs.

Dogs and cats cannot transmit heartworms directly to each other. A mosquito must bite an infected animal and then bite another non-infected animal 10-14 days later for transmission to occur. For example, if your dog is playing with a heartworm positive dog, it is impossible for one dog to pass a heartworm infection to another dog. However, if your neighbor’s dog is heartworm positive, it is possible that a mosquito could transmit heartworms to your dog over time.

Heartworm Infections Are Preventable!

The good news is that heartworm infections are easy to prevent. There are medications given either orally or topically on a monthly basis that kill the immature heartworms in your pet’s blood. This prevents the worms from becoming adults and setting up shop in your pet’s heart and lungs. I prefer to use ivermectin based products, like Heartgard, in my practice as they have been shown to be very safe and are cleared from the body quickly. I recommend talking with your local veterinarian to get the safest and most effective prevention for your geographical area.

Testing For Heartworms

Your veterinarian can do a simple blood test to screen your pet for heartworms. This blood test can accurately detect adult heartworms. Yearly tests are recommended to ensure that your pet has not become infected.

Heartworms In Cats

Cats have less diagnosed heartworm infections compared with dogs. This is because cats seem to fight off infection more effectively. However, heartworm disease is more difficult to diagnose in cats and they show fewer symptoms. As a result, it’s possible that veterinarians are missing many of these infections. Your local veterinarian can help you decide if your cat could benefit from heartworm prevention.

If you have questions about heartworm prevention and your pet, I would love to hear from you! Leave a comment below!

With love,

Dr. Angie