06/23/2026
This handsome guy is Woody, a dog recently adopted by Dr. Sutton from a local shelter. Just a few weeks after joining his new family, Woody tested positive for heartworm disease.
Many pet owners are surprised to learn that a dog can test negative for heartworms (as he did at the shelter) and then test positive shortly afterward. That's because heartworms have a long life cycle. When an infected mosquito bites a dog, it transmits immature heartworm larvae. These larvae take about 6-7 months to mature into adult heartworms. Heartworm tests detect proteins from adult female heartworms, so if a dog was infected recently, the infection may not show up on a test yet.
One of the most fascinating findings in Woody's case was seeing microfilaria under the microscope! Microfilaria are tiny baby heartworms that circulate in the bloodstream after adult heartworms reproduce. In the video attached in the comments, you can actually see these microscopic parasites moving through a drop of Woody's blood.
While heartworm disease can sound scary, the good news is that it is preventable. Cases like Woody's are exactly why we recommend year-round heartworm prevention for all dogs. Prevention is safe, effective, and much easier (and less painful) than treating an established infection.
The even better news? Woody couldn't be in better hands. Dr. Sutton and our team have already developed a treatment plan, and he'll be receiving the very best care every step of the way.
Please join us in cheering Woody on as he begins his journey to becoming heartworm-free!
