If your dog's been on consistent heartworm prevention and you miss a single dose, the risks are going to be pretty low. We just need to get started back on heartworm prevention as quickly as possible. The best thing to do in that situation, because it does kind of depend on the specific circumstances, would be to contact your veterinarian and get their advice as to whether there should be an additional heartworm test. At least find out when the next heartworm test should be, depending on how long there was a lapse. But if you miss a few days here and there, it's not likely to be a big deal, but it is still crucial to try to stay on time as much as possible.

Heartworms are on the rise, and it depends on the area. In the Southeast United States, they're pretty common in dogs not on preventatives. You can look at theheartwormsociety.org, and they have incident maps there that are interesting. And you can look and see how it has increased over the years. I believe the incidents in our area are up about 12% or something like that, but I might be wrong. And it changes all the time. If you're near a heat stamp or water or something like that, rural areas can be hot spots for heartworm. Some cities are warmer, so they promote mosquito growth for more extended periods. And how many positive reservoirs are running around? It depends on many things, but it's relatively common in dogs not treated or on preventative medication.

Heartworms are visible via ultrasound in some cases. You will not see them because they live inside the heart and the pulmonary arteries, so you’d need some advanced imaging to be able to see them.

It’s not painful, per se, but they feel sick, uncomfortable, and they're likely having difficulty breathing. They're not perfusing very well, so they don't feel well. Is it overt pain? I'm not sure.

A dog can show signs of heartworm as early as about six months. They typically don’t show any symptoms before that, as the infestation isn't mature enough at that point.

In a dog, typically, you're going to see coughing. And that's the most common sign. Sometimes, weight loss, you'll see that as well. Those are the two most common signs. Labored breathing, sometimes, as well. And then, as it advances, you can get heart failure and some other things, but those are the big signs. Anytime we have a dog coming in, coughing, gagging, and that's not on heartworm preventative, we highly recommend a test.