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.

Dogs that are outside or in pens all of the time can be inundated with mosquito bites compared to a dog that's more indoors. Of course, your field dogs, your hunting dogs, things like that probably have a higher risk. All dogs have risks despite their lifestyle, but certain dog lifestyles are higher risk, such as predominantly outside and athletic dogs.

If your neighbor doesn't treat for heartworms, you're also at a bit more risk than if everybody around you treats for heartworms, which you don't know.