With today being Valentine's Day, there's no better time to talk about heartworm prevention as an essential way of demonstrating how much we love our pets.

While easily preventable by relatively low-cost medications, heartworm disease leads to severe and potentially deadly respiratory and cardiovascular issues if left untreated.

What are heartworms?

Heartworms are parasites that inhabit dogs' cardiovascular systems, where they multiply and wreak havoc on animals' blood vessels, heart, and lungs. Adult heartworms can reach 12 to 14 inches in length, and as they grow in size in number, their health effects increase.

Treatment for heartworm-positive dogs is also expensive, though the cost varies based on the veterinary provider, the dog's size, and the severity of the individual case. While canines such as dogs, coyotes, and foxes are the preferred host for heartworms, these parasites also cause illnesses in ferrets, wild cat species, and domestic cats. While heartworms can't become fully mature in cats, the immature worms still cause potentially deadly problems. Unfortunately, cats can't be treated for heartworm disease with the currently available medication options, making prevention critical for kitties.

Can my dog catch heartworm disease from another dog?

Heartworm disease isn't contagious between dogs, and humans cannot catch heartworm disease. Heartworms are spread when a mosquito bites a heartworm-positive dog and ingests immature heartworms known as microfilariae. When that mosquito goes on to bite another dog, the parasite then enters the dog's bloodstream. If the dog is up-to-date on heartworm prevention, the medication will prevent the parasites from maturing and reproducing. According to the AVMA, heartworm disease is present in all 50 US states and prevalent globally, underscoring the importance of heartworm prevention.

What if my dog is heartworm positive?

If a dog develops heartworm disease, it's crucial for them to be treated, preferably early on and before the dog develops symptoms. Veterinarians typically screen dogs for heartworm disease annually, and if a dog is heartworm positive, they can recommend the best course of treatment. While heartworm disease is expensive, treatments have improved significantly over the years, and the most up-to-date treatment protocol has a 95% success rate.

During heartworm treatment, dogs must remain calm and maintain a low level of activity to prevent large pieces of dead heartworms from breaking off and traveling to the lungs, where they can cause a potentially deadly pulmonary embolism. Heartworm treatment is essential to restoring an infected dog's quality of life and lifespan.

How can I help LCHS dogs who are heartworm positive?

While LCHS provides heartworm preventative for all dogs in our care, many are already heartworm-positive when they enter the shelter. By donating to our heartworm treatment fund, you can help us to provide treatment for heartworm-positive dogs and start them on the road to recovery before they're adopted.

Another way to help is by fostering a dog that is heartworm positive or recovering from heartworm treatment. Because they need to stay calm during their recovery, recently heartworm treated dogs benefit greatly from staying in a quiet, comfy home. To apply to foster, please visit to fill out a foster application. Please give us 24 to 48 hours to review your application. Once your application has been approved, please email to arrange a time to meet with potential foster pets.