Every dog owner in San Antonio should understand the connection between mosquitoes and heartworm disease. Unlike the many pest problems that are primarily a nuisance, this one is a genuine health risk to your pet. The good news is it is also very preventable, and keeping mosquito pressure down in your yard is a meaningful part of that prevention.
Quick answer
Yes. Mosquitoes transmit heartworm disease to dogs, and heartworm is endemic throughout Texas including the San Antonio area. A single infected mosquito bite can transmit larvae that develop into adult heartworms inside your dog's heart and pulmonary arteries over six months. Heartworm disease is serious, expensive to treat, and preventable. Monthly heartworm prevention and reducing mosquito pressure in your yard are both part of protecting your pet.
Want this handled for you?
Protecting your dog from mosquito-transmitted disease starts in your yard. Schedule a treatment with Mosquito Guard Pro and we will reduce the mosquito pressure around your home so your pets can spend time outside safely.
How Mosquitoes Transmit Heartworm
Heartworm disease (Dirofilaria immitis) is transmitted exclusively by mosquitoes. An infected mosquito bites a dog and deposits microscopic larvae into the bite wound. Those larvae migrate through the dog's tissue over the next few months, eventually reaching the heart and the large blood vessels of the lungs, where they mature into adult worms that can grow up to 12 inches long.
The worms live in the heart and pulmonary arteries and cause inflammation, blockage, and eventually organ damage. A dog with a heavy worm burden may show no symptoms for months to years, which is why the American Heartworm Society recommends annual testing even for dogs on prevention.
How Common Is Heartworm in San Antonio?
Texas is one of the highest-risk states for heartworm transmission in the United States. The American Heartworm Society's incidence maps consistently show significant heartworm-positive rates in Texas, particularly in the Gulf Coast region and the areas to the south and east of San Antonio. Bexar County's warm winters, high humidity, and abundant mosquito habitat make it an area where veterinarians see heartworm cases year-round, not just in summer.
The American Heartworm Society recommends year-round prevention for all dogs in the Gulf Coast and Southeast regions, which includes the San Antonio area, because the mosquito season is effectively twelve months.
Can Cats Get Heartworm From Mosquitoes?
Yes, though cats are not natural hosts and the disease presents differently. Cats often have fewer worms than dogs and may clear the infection on their own, but the immature larvae can still cause serious lung damage in a condition called heartworm-associated respiratory disease (HARD). There is no approved treatment for cats with adult heartworms; management focuses on supportive care. Prevention is the only reliable approach for cats as well.
Is Professional Yard Treatment Safe for Pets?
This is a common question, and it is a fair one. EPA-registered barrier treatments used by professional mosquito control companies are applied to vegetation and shaded surfaces, not to open turf where pets spend most of their time. The standard guidance is to keep pets off treated surfaces while the product is wet, typically 30 to 60 minutes after application, and to let the treatment dry completely before allowing pets back into the yard.
Your technician will give you specific re-entry guidance based on the products used. Professional barrier treatment is not a blanket spray of the yard; it is targeted application to resting and harborage spots, which reduces the exposure area significantly.
Reducing adult mosquito populations in your yard reduces the number of opportunities for infected mosquitoes to bite your pet. It is not a substitute for veterinarian-prescribed heartworm prevention, but it is a meaningful additional layer of protection.
What to Do on Your End
Keep your dog on a monthly heartworm preventive recommended by your veterinarian. Have your dog tested annually, even if they have been on prevention consistently, because no preventive is 100 percent effective and early detection makes treatment far more manageable.
Reduce standing water in your yard. Pet water bowls left outdoors are a common mosquito breeding site; empty and refill them daily. Check that outdoor pet kennels drain well after rain. If you use a kiddie pool for your dog, empty it after each use.
Professionally treating your yard for mosquitoes does not replace prevention, but it reduces the background pressure significantly, especially for dogs that spend a lot of time outdoors.