Heartworm FAQs

Mosquitoes carrying heartworm larvae transfer the parasite and infect dogs. There's no other way to transmit heartworm disease, but one bite is all it takes. 

Heartworm disease has been reported in all 50 states. The Houston area has one of the highest rates of infection in the country. The good news is that it's easy to prevent. Moreover, it can be treated, though prevention is critical. Here's are the most frequently asked questions about heartworms.

What happens after an infected mosquito bites a dog?

Approximately seven months after the mosquito bite, larvae mature into adult heartworms. They lodge in the dog's heart, lungs, and surrounding blood vessels, where they begin reproducing. Adult heartworms can grow up to 12 inches in length and live five to seven years. A dog can have 250+ worms in its system.

If one of my dogs has heartworm disease, can he give it to my other dogs?

No. Again, only mosquitoes transmit heartworms. Even if a mosquito bit your infected dog and then bit your uninfected dog the same night, it wouldn't transfer the parasite. That's because there's an incubation period before the mosquito becomes infectious.

How can I prevent my dogs from getting heartworm disease?

There are monthly pills, monthly topicals, and a six-month injectable product to prevent heartworm. A year of protection costs between $50 and $200, based on the type of preventative you select and the weight of your dog. You will need to take your dog to a vet (or even select pop-up immunization clinics) for an annual heartworm test and prescription for preventive. It can be purchased from vets or even online.

What are the signs of heartworm disease in dogs?

In the early stages of heartworm disease, few dogs show symptoms. 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 build up.

What can I do if my dog has heartworm disease?

There are treatment options, known as "fast kill" and "slow kill." Each has advantages and disadvantages, so do your research. Our shelter offers the "fast kill" treatment (at the time of adoption for heartworm positive shelter dogs) at a highly subsidized rate. In many instances, treatment for our shelter pets is sponsored by volunteers or Facebook followers. We recommend you take advantage of the subsidized treatment, though you can opt to pursue treatment with your veterinarian. After treatment, most dogs go on to live full, healthy lives--we've treated hundreds of dogs that now show no signs of the disease or adverse effects.