Remember Penny, our sweet little girl Kristin was fostering? Six weeks ago, when she was pulled from certain death and rescued by Kristin, she tested negative for heartworms. Although Kristin was able to find her a good home, she just couldn’t let her go. So we ran some basic blood tests on her to make sure she was perfectly healthy, and the heartworm test was repeated with our outside laboratory. This time it was positive! We repeated it with our tests, and sure enough, she is positive.

The “C” is for control, so it’s purple to show that the test is working. The “T” is for the test, and it is faintly purple, and therefore faintly positive for heartworms. So we were in an unusual position to know exactly when Penny became infected, and we thought it was a good time to review just how heartworms and heartworm tests work. So here we go (in a nutshell)….

Mosquitos transmit heartworms from one dog to another. The “baby” heartworms transmitted into the skin travel to the heart via the bloodstream, and they grow into large worms resembling small earthworms. This takes about 6 months, and heartworm tests will only detect adult worms. Therefore, a dog must be infected for 6 months before a test will show positive. This means Penny was infected 6-7 months ago, or sometime in June or July. Here, you see our ultrasound of the actual worm. They typically prefer the right atrium of the heart, but Penny’s is sitting in the right ventricle. Blood in the heart chamber is black, and the white striped spots in the middle of the black is the worm.

Penny has already been on heartworm prevention since her original test was negative. This heartworm prevention kills the “baby” worms, so they won’t be able to develop into more adult worms. We now will decide whether or not to inject her with Immiticide to kill the single adult worm or use homeopathic herbs to kill the worm slowly. Stay tuned and remember to keep your dogs (and cats) on heartworm prevention every month! Remember, we get mosquitoes year-round here, and mosquitoes come indoors too!