A silent killer

Heartworms post year-round threat for Texas pets

BY: TIFFANY DITTO

Staff writer

Mosquitos are a nuisance for humans spreading diseases like the Zika virus, malaria, dengue fever, West Nile virus, yellow fever and many others. But they're not just a threat to humans, they're also a threat to your furbaby.

For Texas dogs, heartworms pose a year-round threat. Texas' warm, humid weather is the perfect breeding groundfor mosquitoes and all it takes is just one bite from an infected insect to give your baby heartworms.

Pets are more susceptible to heartworms in Texas because they contract them from mosquitoes, which stay present in Texas all year long," said Dr. Suzie Smith, a contract wellness veterinarian for Texas Coalition for Animal Protection. "Texas never has a full freeze that lasts long enough for mosquitoes to hibernate, or completely die off. In fact, I got bit by a mosquito when it was 54 degrees outside. Pets don't even have to go outside to be bitten by a mosquito because I have found them inside my suburban area home the day after it snowed!

Heartworms can grow up to a foot long and live in the arteries of dog's and cat's hearts and lungs. Since dogs are the parasite's natural host, this worms thrive inside of their bodies and can multiply until your pet has hundreds of worms living in their heart muscle — causing irreversible damage.

Dr. Beau Black, an associate veterinarian at Town and CountryAnimal Hospital in Aubrey, said these worms are easy to prevent, but especially dangerous if pet owner's don't keep their pet on prevention.

Heartworms are dangerous because they can infect un-protected dogs by migrating to the heart and growing in the pulmonary artery," Black said. "Enough heartworms can eventually obstruct the pulmonary artery, leading to right-sided heart failure. This damage can be permanent to the heart muscle, and lead to ascites (fluid in the abdomen) and liver failure.

Heartworms develop in the heart and bloodstream of infected pets. When they lay larvae these "baby worms" are distributed throughout the bloodstream. These larvae can then be sucked up by a mosquito when it bites your pet. Once this happens, the mosquito is now infected and able to transmit the disease to other cats and dogs.

For your pet to be diagnosed as heartworm positive, the worms must develop into adults. This process typically takes about 6 months. Because of this, the American Heartworm Society recommends testing your pet for heartworms once a year. Any test done before the worms develop into adults could result in a false negative, when in reality your pet is infected with the dangerous parasite.

According to the American Heartworm Society, symptoms of heartworm disease in dogs include a persistent cough, shortness of breath or reluctance to exercise, fatigue after moderate activity, weight loss, decreased appetite and sudden collapse from blood flow blockages. Many of these symptoms aren't present until the disease is in the advanced stages — meaning the worm burden on your pet's heart is large.

Heartworms can be silent killers," Smith said. "For some pets, there are no symptoms until the disease is more advanced. When it is more advanced, it can cause breathing difficulties, heart failure and even renal failure.

The best way to prevent your pet from getting heartworm disease is to keep your pet on year-round prevention. Different kinds of prevention exist. The most popular is once monthly chewable tablets of Ivermectin — a drug known to kill infant worms, preventing them from ever maturing into adults. These chews range in price, but many companies, like Heartgard, guarantee their product and will pay for your pet's treatment should they become infected with the parasite while on their prevention.

There are also injectable preventions like ProHeart 6 and ProHeart 12. These medications are administered by a veterinarian and last for either six or 12 months. All heartworm preventatives require a prescription from a veterinarian, so make sure the next time your pet is at the vet, you make it a priority to get your pet started on prevention or renew your pet's prescription.

Pets are diagnosed with heartworm disease by collecting a blood sample and then using a specialized antigen test to detect the presence of the worms. If your furbaby is diagnosed with heartworm disease it's not necessarily a death sentence, but it will cost you hundreds or even thousands of dollars to get your pet heartworm free. Furthermore, treating the disease is not easy, and requires that your pet follow a strict regimen of no activity for at least 4-6 weeks.

Heartworm treatment (immiticide) is the only recommended treatment by the American Heartworm Society for dogs with heartworm infestation," Black said. "The treatment consists of immiticide injections, which kill the adult heartworms. These dead worms have to decompose and worm fragments can lodge in the distal pulmonary arteries and capillaries in the lung lobes, resulting in a thromboembolism [blood clot] and cut off blood flow to a portion of the lungs. Increased blood flow and blood pressure increases the likelihood of permanent fibrosis [excess tissue development] and scarring of the lungs. This is the main reason it is so important to restrict exercise, especially the four weeks after the immiticide injections.

Immiticide injections are painful for pets, and veterinarians often have to give pets pain medication while they receive treatment. The best way to ensure that your pet stays happy and healthy is to prevent heartworm infection by keeping your pet on prevention.

Prevention is 99.9% effective at keeping your pets from having any of those heartworm related complications and there are so many cost-effective options," Smith said. "Treating heartworms, although effective, can be very harsh on your pet's body and does not undo the damage that heartworms inflict on your pet's heart and other vital organs.

For more information, visit heartwormsociety.org.

Texas ranks 4th in the nation for the most reported cases of heartworm infections, according to 2016 data by the American Heartworm Society.

Photo courtesy of American Heartworm Society

Twitter: @TiffanyDitto