cat and dog

Prevent Heartworm in Pets Year Round

If you’ve been to a veterinarian’s office, chances are you’ve seen the photos on the wall of worms growing from the heart of a dog or cat. Although these images may be unsettling, the message is clear: Heartworm disease is fatal to pets. The good news: You can protect your pet from this disease.

“It’s a preventable disease, which is why it’s so frustrating as a practitioner when you see a case. Heartworm disease is very serious and the treatment is not very easy on infected animals,” says Melanie McLean, D.V.M., a veterinarian at the Food and Drug Administration (FDA). “It’s much easier and healthier for the pet to prevent the disease in the first place.”

Heartworms are carried by infected mosquitoes that transmit parasitic worms that grow in the arteries of the lungs and heart of dogs, cats, and other species of mammals. The heartworm larvae enter the bite wound and move through the pet’s body and can grow up to 12 inches long.

The disease is not contagious from one pet to another and heartworms in humans are very rare.

Putting Pets at Risk

Veterinarians often prescribe heartworm prevention medicine for pets to take year round. Due to the link to mosquitoes, some owners opt out of treating their pets during the winter months, but veterinarians see this as an unnecessary risk to the pet’s health.

“You never know when the first mosquito is going to come out, or when the last mosquito is going to die. Heartworms have been reported in dogs in all 50 states and just because you live in a colder climate state doesn’t mean that your dog is safe,” McLean warns.

Animal owners who stop giving heartworm prevention medication during the winter run the risk of their dog or cat contracting heartworms. If the animal becomes infected and the heartworm preventative is later resumed without testing, the owner may be putting the pet in danger. The preventive medicine can kill so many microfilariae (the offspring of adult, female heartworms) at once that it could shock the animal’s system, with potentially fatal results. Also, preventatives will not kill adult heartworms and they will continue to reproduce.

For this reason, testing your dog or cat prior to starting a heartworm preventive medication is essential, especially since pets that have heartworms may not show symptoms right away.

If your pet tests positive for heartworms, it’s crucial to the success of treatment to follow the veterinarian’s directions. Only one FDA-approved drug, Immiticide (melarsomine hydrochloride), is marketed in the U.S. to kill adult heartworms in dogs. Immiticide, which contains arsenic, is given by deep injection into the dog’s back muscles. And only one drug, Advantage Multi for Dogs (imidacloprid and moxidectin), is FDA-approved to get rid of microfilariae in the dog’s bloodstream. It’s applied topically to the dog’s skin.