The risks are pretty significant because if heartworm disease is left untreated and essentially unprevented, it's probably not going to end well for that dog. It may not be next week or next month, but at some point, that disease will rear its ugly head, and usually by the time it does, it’s not good. They basically die of heart failure.

That's a tricky question to answer. I guess you could look at it in three ways. So number one, heartworm prevention is extremely imperative. I recommend it to everybody. Very seldom do I see complications with just preventatives. And that kills the infective stage of the heartworm that the mosquito tries to give the dog. So the risk isn’t zero but it’s close. If an animal's positive for heartworms, that means they have adult worms there. And if we go through with that treatment, there's risk associated with that because you are killing these worms that live, again, in the right side of the heart. And as mentioned, they're pretty long (six to eight inches) so killing them is half the battle, but they're still there. So now the body and immune system have to break down that dead worm and dispose of it, for lack of a better word. Well, what happens if they don't do it properly? What happens when that dog's too active after treatment? Then that dead or dying worm, or even partly disintegrated worm, can still migrate and go to the lungs and cause problems there. And the drug itself, while I seldom see reactions or problems to it, it's a pretty harsh chemical. It's got to kill a bunch of big, active heartworms. Any time you put a chemical in the body of a living creature, things can happen that you don't want to happen or don't expect to happen. Do I see it commonly? No, I do not. But they can have pain at the injection site, soreness, and I’ve seen some dogs that are wobbly on their backend. The third and final portion of this long answer is that sometimes when dogs have adult heartworms, those adults will reproduce and cause microfilaria, or baby heartworms. That takes a different modality to treat it. Some preventatives treat that nowadays, but oftentimes we'll use a high dose of ivermectin or something to kill that. Can you have side effects from that? Yeah. It's a high dose of ivermectin. Ivermectin is commonly used as a dewormer or heartworm preventative, but not usually at these levels. You can have dogs that might have a sensitivity to ivermectin, which can cause neurologic signs. You wouldn't want to give that to a Collie breed type of dogs, so Border Collies, Collies, Australian Shepherds, or any of those kinds of herding breeds. You’ve got to be careful when giving high doses of ivermectin. So all these complications are very rare, but they can happen.

Unfortunately, yes, depending on where you live. Let me answer it this way—if you have mosquitoes where you live, then yes. They are how the disease is spread so, if you live, say, in Canada where there are no mosquitoes, it's not going to be a big deal to you guys. But here in South Louisiana, the Gulf Coast, and the majority of the United States, I would say it's a pretty big issue.

Why do they call it heartworm? Because the worms live in the heart. I'm not saying that to be silly, but anything that lives in the heart is obviously going to be detrimental. These worms can get pretty good-sized. Believe it or not, they can reach six to eight inches long, so that's a pretty good size. If you get one or two, it’s probably not a huge deal. If you get 10 or 12, it’s starting to become a big deal now. If you get more than that, well, you can imagine. Common sense would tell you that's going to begin to affect how efficiently and effectively that the heart can pump. Can those valves seal off? Is blood flow going to be impeded in going to the lungs to get oxygenated? All that stuff is a factor, so there are some very significant signs associated with the disease itself. And some of those changes are irreversible if they've been there for long enough, even if the dog is treated.

I get asked that one every now and then as well. The simple answer is, no. I can't really justify a reason for me to say that's better. I've been doing this for over 20 years and I can count maybe not on one hand, but probably on two hands, how many times an animal has died peacefully on their own at home. It just doesn't happen very often. They fight. They hang on. They just don't let go the way that we would want them to let go. So oftentimes it stinks, but we as veterinarians and sometimes you as owners have to make that hard decision for them. I encourage people to think of it not as being cruel because I, too, struggle with that. What gives me the right to do that? What gives me the power and the right to decide if an animal lives or dies? It's a weird power to yield, but I've come to realize that it's the last bit of love that we can give them. It really is. When you know that the end is there, there's nothing else you can offer and there's nothing that's going to make this animal turn around. Isn't it kinder to let them go with dignity, pain-free, in a controlled, loving setting where their owner can be right there with them, holding them, talking to them? I would like to go that way. I hope that that can be done for me one day, and I know it can't, but who wouldn't want to pass that way in that situation. So, yeah. I think it is much more feasible and humane for the animal to ease them in their passing, as opposed to drawing it out and just waiting and waiting and waiting for them to pass at home.