Don't Risk It: The Ultimate Guide to Heartworm Prevention!

Get ahead of heartworm season with expert guidance from Dr. Xenia Zawadzkas and Dr. Tyler Sugerman in this informative podcast episode. Learn why heartworm prevention is crucial for your pet's well-being and uncover the most effective preventive measures available. With practical advice and actionable tips, this episode empowers pet owners to take proactive steps in defending their beloved animals against this potentially deadly disease. 

In this episode you will learn:

• The importance of heartworm prevention for pets
• Common misconceptions about heartworm disease debunked
• Insights into the lifecycle of heartworms and their impact on pets
• Effective preventive measures and treatment options discussed
• Practical tips for safeguarding your pet's health and well-being
• Expert guidance on choosing the right heartworm prevention strategies
• Actionable steps to take for proactive pet care against heartworms

Resources:
American Heartworm Society

Transcript

Dr. Tyler Sugerman: 0:00

Today on Vetsplanation, we are tackling a silent threat lurking in the shadows for our pets. It's called heartworm disease. It's an often overlooked, but unfortunately, potentially deadly disease for our pets. Heartworm prevention is really the key cornerstone to trying to help prevent this disease for our cats and our dogs. Join us as we dissect the danger this parasite poses and arm yourself with the knowledge to be able to protect your beloved companion. From the life cycle of the heartworm, to the latest prevention strategies, we are covering it all. So welcome to Vetsplanation, the vet podcast for your pet. I'm Dr. Sugerman and we're gonna be joined today by Dr. Z. So tune in to learn why preventing heartworm isn't just a recommendation. It is a necessity. This episode could be the difference between a healthy pet and a heartbreak. So don't miss it. And don't forget, if you like our content and want to hear more of it, make sure to subscribe and leave us a five star review. Hey everybody, welcome back to another episode of Vetsplanation. I have our pretty much resident expert here now, Dr. Z with me again, and I am your host, Dr. Sugerman. So today I'm really excited, we're going to be talking about something that's apparently been a hot topic in our office, at least. We're going to be talking about heartworms.

Dr. Xenia Zawadzkas: 1:17

Yes. Heartworm disease. Another fun parasite to talk about in detail.

Dr. Tyler Sugerman: 1:23

Let's start off, what is heartworm?

Dr. Xenia Zawadzkas: 1:26

So heartworm is a, it's a worm. The Latin name is Dirofilaria immitis. If we break that down,'diro' means it's like dire, terrible, fearful, dreadful, formidable, that's what diro means. So it's a nasty one.

Dr. Tyler Sugerman: 1:42

Yeah, it has to be terrible. Yeah.

Dr. Xenia Zawadzkas: 1:44

And then filaria means like a thread-like worm, like filament. It's like a thread. And then immitis actually means harsh and cruel. So it's a very negatively named worm.

Dr. Tyler Sugerman: 1:57

It sounds terrible. I don't think I've ever heard any other worm named something like that.

Dr. Xenia Zawadzkas: 2:00

Yeah. I don't know if I've broken down the names of other words, but like I looked this one up, I'm like, Oh yeah, that makes sense. Not a nice worm. Yeah. So adult heartworms, they are skinny about a foot long when they're adults. So about the size of your forearm, usually length, I should say.

Dr. Tyler Sugerman: 2:17

Yeah. That's long.

Dr. Xenia Zawadzkas: 2:17

Yes, they're very long when they're adults. And they live in the heart and the lungs and the associated blood vessels. They infect many different animals. The big ones is dogs, of course. But they can also get into cats, ferrets, wolves, coyotes, foxes, sea lions, harbor seals, bears, muskrats, raccoons, red pandas, leopards, and wolverines. We've found them in all those kinds of animals. And those wildlife carriers are important, unfortunately they keep the parasite going. So they can get into these other species. Even they've been into humans before, too. Like people have found them incidentally. An x-ray of their chest and there's like a spot in their lungs and then they biopsy and they find like heartworms. It's like a granuloma that was just subclinical hanging out in there. So pretty nasty. Even can get in people. But that's not the main host so they don't really do much else besides make a small little spot. That's not a big deal. So don't worry too much.

Dr. Tyler Sugerman: 3:16

Good. Good.

Dr. Xenia Zawadzkas: 3:17

For people. Let's see. They really prefer the canids though. That's their definitive host, and that's when they can complete their full life cycle, as we'll go into. But since they're in all these wildlife species, and they can get into other animals, it's just impossible to eradicate them, probably. We will always be dealing with them, and it's important to continue to protect our pets and ourselves from these kinds of parasites.

Dr. Tyler Sugerman: 3:39

And the wildlife.

Dr. Xenia Zawadzkas: 3:40

Yes.

Dr. Tyler Sugerman: 3:40

I actually have seen a harbor seal that had heartworm.

Dr. Xenia Zawadzkas: 3:44

Did you? See? Interesting. I've heard about the seals getting it because they sun themselves and I'm sure the mosquitoes are out there.

Dr. Tyler Sugerman: 3:49

Exactly. I mean, they're just so far out though, like it is interesting like how, but I guess they do come closer and closer, especially when people start feeding them fish.

Dr. Xenia Zawadzkas: 3:55

Yeah. The city harbors, there's seals everywhere.

Dr. Tyler Sugerman: 3:57

Exactly. Exactly.

Dr. Xenia Zawadzkas: 3:59

So because the wildlife are harboring these worms. And keeping them around. It's very similar to rabies. Like that's a virus. It's not a parasite. But it's because it's in the foxes and the bats and the wolves and other places it's constantly a threat and there's probably no way we're ever gonna be rid of it. Yeah, we just can't get it out of those wildlife populations. So yeah, the companion pets that we have are like our buffer from rabies. So if we keep them vaccinated, then we won't ever get rabies. Hopefully it happens sometimes, that's the idea. And that's why rabies is so important to like, that the governments are like, you have to vaccinate. It's required by law. It's not like similar for heartworm because it doesn't kill people like rabies does, but my point is that the wildlife harbors it, and we just can't ever be rid of it, and it's always a threat.

Dr. Tyler Sugerman: 4:47

That makes a lot of sense.

Dr. Xenia Zawadzkas: 4:47

Yeah.

Dr. Tyler Sugerman: 4:48

So I know you always have like fun facts for us. Do you have any fun facts for us about heartworm?

Dr. Xenia Zawadzkas: 4:52

Yeah, just some historical things. I was trying to look up the history of heartworm, and there's not a lot out there, but apparently in 1586, there was some person, I forgot his name, but I tried to look him up and I couldn't find anything on him. But apparently he drew a picture of a monster worm. Like it was a worm that was like a monster, had a monster face on it. And it was in the heart of a horse. And so that was like the first documented possibility of heartworms being found. But really they pop up more in South America. They were documented in the 1800s and then by 1856 they were found on the southeast coast of the U. S. area. And then almost a century later, 1974, is when the American Heartworm Society was established. Those are my little historical factoids about Heartworm.

Dr. Tyler Sugerman: 5:41

I will say, so my daughter came home the other day and she was talking about how there's this crazy blood death worm. And I thought about your Heartworm stuff, and I was like, I wonder if that was the same thing that they were writing about. But I don't know.

Dr. Xenia Zawadzkas: 5:53

You should ask.

Dr. Tyler Sugerman: 5:54

Yeah she had it in a book at school, so I'd have to ask her to, to which book it was.

Dr. Xenia Zawadzkas: 5:57

I'm curious which worm it was.

Dr. Tyler Sugerman: 5:58

Yeah

Dr. Xenia Zawadzkas: 5:59

Blood death worm?

Dr. Tyler Sugerman: 6:00

A blood death worm. I don't think it's a real thing from what I looked up, because it she said the title was, like, the very true story of, so I feel like it maybe is not a true story,

Dr. Xenia Zawadzkas: 6:10

Yeah, I think there's a lot of myth around worms in general and, monsters.

Dr. Tyler Sugerman: 6:14

Exactly. They're creepy.

Dr. Xenia Zawadzkas: 6:16

They are super scary.

Dr. Tyler Sugerman: 6:16

Exactly.

Dr. Xenia Zawadzkas: 6:18

It makes everybody's skin crawl.

Dr. Tyler Sugerman: 6:20

Yes, exactly. So how does a pet get heartworm?

Dr. Xenia Zawadzkas: 6:23

So they are transmitted by mosquitoes. Straightforward, they get bit by a mosquito. That's how they get it. And we'll go into the whole life cycle, but to answer that simply.

Dr. Tyler Sugerman: 6:34

Perfect. And then I think you mentioned this before both dogs and cats get heartworm, is that correct?

Dr. Xenia Zawadzkas: 6:39

Correct? Yeah, so dogs again are their natural host, but the parasite can complete its life cycle best in those species. Cats can get them too, they just don't usually get very far, because the cat's immune system is just better at killing the baby heartworms on its own. And occasionally one adult will make it to the heart, but usually it's just one worm that we find incidentally. Or up to three, I think has been reported. There are like three total adult worms, but in dogs on the other hand, hundreds of them can get into their heart eventually.

Dr. Tyler Sugerman: 7:09

Wow.

Dr. Xenia Zawadzkas: 7:10

Yeah. Cats also, they can't tolerate the adulticide treatment, like to kill the adult worms. Like it will kill the cat. So you just, there's no treatment for it in cats. So your best bet is to just prevent it. And when cats get the baby heartworms circulating around usually they just get into their lungs, the baby heart worms, and then they get coughing is the big symptoms. So they look like they're asthmatic.

Dr. Tyler Sugerman: 7:30

Asthmatic, yeah.

Dr. Xenia Zawadzkas: 7:31

They like just have a cough. And that's usually, we just treat'em the same. We just give them steroids and stuff to get the inflammation down and get them to cough less. But you can't really treat the worms themselves, unfortunately, in, in cats. You can kill the baby ones with the preventatives, but you can't kill the adults. So it's a bum deal if a cat gets them.

Dr. Tyler Sugerman: 7:51

I know, right?

Dr. Xenia Zawadzkas: 7:52

Yeah.

Dr. Tyler Sugerman: 7:52

Poor cats.

Dr. Xenia Zawadzkas: 7:53

It's bad for the dogs too, obviously, but at least we can do something or try to do something for them.

Dr. Tyler Sugerman: 8:00

So how do the heartworms actually get into the heart then? You have to be bit by the mosquito, but then how does that go to the heart?

Dr. Xenia Zawadzkas: 8:06

Yes. Let's review the anatomy of the heart, if you don't mind, real quick, for people that don't really know. I think most people know there's four chambers in the heart two ventricles and two atriums, or atria. So the ventricles are on the bottom, and then the atriums are on the top. So there's the right side and the left side. Blood travels from the body through the veins, back into the right side of the heart. First it goes into the right atrium, and then from there it goes down into the right ventricle, and then that ventricle is very, the muscular, big muscular part. So that pumps it right from the right ventricle up into the lungs. That's where the right side of the heart is going. In the lungs is where we breathe, we get oxygen, and then the blood is oxygenated. And then it goes right back to the heart. the left side, and to the left atrium, and then the left ventricle, and then that left ventricle is even more strong, and it pumps the blood all the way to the rest of the body again. So we then get our fresh, oxygenated blood for the rest of the body. So that's the path of the blood. So when these little baby worms are traveling, And migrating through the body of the dog, they are making their way into the veins and back into the heart. So eventually they'll get into the right side of the heart and that's where they love to be. That's where the adults end up maturing. So they're mostly in the right ventricle and up into the pulmonary artery that goes up into the lungs. Yeah. So they're actually mostly in the lungs rather than in the heart.

Dr. Tyler Sugerman: 9:31

Yeah. You think it'd be called the lung worm but that's a totally different thing.

Dr. Xenia Zawadzkas: 9:34

Totally different. Yeah, those are actually in the airways whereas the heartworms are in the blood that's going to the lung. So it's a little different, a lot different, but just so people know that's where they're hanging out. They like, actually, the less oxygenated blood and they like to stay right there in the pulmonary arteries.

Dr. Tyler Sugerman: 9:52

It's so weird that they want to go into a less oxygenated thing.

Dr. Xenia Zawadzkas: 9:55

Yeah. I think they just evolved that way because they're pumped that way towards the heart once they start migrating.

Dr. Tyler Sugerman: 10:01

Yeah.

Dr. Xenia Zawadzkas: 10:01

I don't know. Let's go through the whole life cycle. It's a pretty crazy life cycle and it's pretty impressive. When I first learned about it years ago, I was like, wow, this is just nuts. How they developed to do all these things and the fact that it works, that they can complete a life cycle in this way. It's just blows my mind.

Dr. Tyler Sugerman: 10:21

It reminds me of the salmon poisoning, like that life cycle.

Dr. Xenia Zawadzkas: 10:23

Yes. With the fluke, and the rickettsial.. And yeah, that's another'Wow, so many things have to come together for this to actually work.'

Dr. Tyler Sugerman: 10:30

Yet we see it so often.

Dr. Xenia Zawadzkas: 10:31

Yeah, but it's somehow very successful.

Dr. Tyler Sugerman: 10:33

Yeah, exactly.

Dr. Xenia Zawadzkas: 10:36

So if the conditions are right, and we'll talk about the conditions, but the whole life cycle takes around seven to nine months to complete, to go from the baby to an adult heartworm. And if we understand this life cycle, I call it know thy enemy, just like with any parasite, if you know their life cycle, again, that's the best way then to fight them and to prevent the problem. So let's start with the adults. They are in the heart and the pulmonary arteries they mate there's males and females and they mate and they produce little babies and then the females give birth to these millions of them. They're called microfilaria. So micro just means tiny, right? Microscopic. And filaria, again, is like little thread. So there's high numbers of these circulating in the blood. And I really have to think about how tiny they are. Like, you can't see them unless you look on a microscope. Not much longer than a few red blood cells put together. So they're really tiny. And these are compared to the adult heartworms and the other stages, they're actually relatively harmless to the dog. Like they're circulating in the blood and the dogs, I think that's why they're a definitive hosts. They don't really have a response to them normally, like they don't mind them being in their bloodstream. So they're just circulating in high numbers all the time and the dogs are okay with this. And these actually they can be passed through the placenta to unborn puppies. So puppies can actually be born with these microfilaria.

Dr. Tyler Sugerman: 11:56

Okay.

Dr. Xenia Zawadzkas: 11:56

But it's important to note that these microfilaria will never turn into adult heartworms. They have to go through a mosquito first. So even though puppies may be born with microfilaria they're not gonna get adults from that. So they're just having them in their blood. These microfilaria before I move on they can live for about two years in the bloodstream before they die of like old age yeah, so..

Dr. Tyler Sugerman: 12:19

That's a long time.

Dr. Xenia Zawadzkas: 12:20

Yeah, they're there. They're a problem. And when they're circulating, that dog is infectious then. It's going to be able to expose other dogs to heartworms by a mosquito. So that's the next step. So the mosquitoes come along and they bite the dog and they suck up some of these baby microfilarias because there's tons of them in there and they're just sucking them up right with the blood that they're getting. Inside the mosquito, over about two weeks is how long it takes, these microfilaria start to molt and grow up. And they go through two different molts. So they start, they go to L1 and then L2, actually three molts, and then L3.

Dr. Tyler Sugerman: 12:58

Okay.

Dr. Xenia Zawadzkas: 12:58

We don't call the microfilaria L1s. The microfilaria are their own thing.

Dr. Tyler Sugerman: 13:01

Just your own thing.

Dr. Xenia Zawadzkas: 13:02

Yeah. And then it goes L1, L2, L3. So once they become L3s inside the mosquito, then they can go back into the next dog. Which is crazy, I know. But then the mosquito will bite another dog and it's carrying the L3s. They don't just inject the L3s. It's interesting, there's videos on YouTube like really, yeah, you can see the mosquito bite and it makes a hole where it's sucking blood and it also spits. Mosquitoes spit a little bit..

Dr. Tyler Sugerman: 13:29

Gross.

Dr. Xenia Zawadzkas: 13:30

Yeah, so there's like a little bubble of spit, like next to where they're biting. And in that spit is where those L3s go, and they're just like swirling around in this mosquito spit. And then the mosquito leaves, but that bleb of spit is still there with the baby worms, on the skin, yeah, on the surface of the skin. And they're just swimming around and then they're like, Oh look, there's that hole that the mosquito just made. And then they like swim down into the hole that the mosquito made with his bite.

Dr. Tyler Sugerman: 13:56

Yeah.

Dr. Xenia Zawadzkas: 13:57

And so then those L3s get into the dog. And that's when they can continue along their life cycle. Over the next six months about take six months for these L3s to continue growing up. I call them teenagers Teenager heartworms.

Dr. Tyler Sugerman: 14:15

Yeah.

Dr. Xenia Zawadzkas: 14:15

They are L3s and then they go to L4s. So then they're like tweens, right? And they migrate through this skin and the muscle and then they finally get into the bigger veins and blood vessels, and then they find their way to the heart and the pulmonary arteries, and that's where they finally become adults. And do a final molt and become, we used to call them L5s, but I was told, nope, now they're just adult. Yeah, there's no L5. They're no longer a larva. They are an adult. Yeah, so it goes microfilaria, L1, L2, L3 in the mosquito, L3, L4 in the dog. The next dog. And then not L5, but adults become into the heart.

Dr. Tyler Sugerman: 14:57

Okay.

Dr. Xenia Zawadzkas: 14:58

So then they breed and produce new microfilaria and the whole thing starts all over again. And one other note I wanna make is that those adults if they're not killed by a treatment, they live five to seven years before they die of old age. In a cat, they don't live quite as long, two to three years has been documented.

Dr. Tyler Sugerman: 15:18

When they're an adult, then they go back to making more microfilaria, right? And then we're just doing this whole process all over again.

Dr. Xenia Zawadzkas: 15:23

You got it. Yep.

Dr. Tyler Sugerman: 15:24

Okay. Sheesh.

Dr. Xenia Zawadzkas: 15:26

I know, it's a nutsy.

Dr. Tyler Sugerman: 15:27

It is crazy. From a dog, back to a mosquito, back to a dog.

Dr. Xenia Zawadzkas: 15:32

You can imagine that they need to have high populations of dogs and high populations of mosquitoes to establish themselves and keep going with this life cycle

Dr. Tyler Sugerman: 15:42

Yeah, well then where are these heartworm found?

Dr. Xenia Zawadzkas: 15:46

Yeah, so warm climates are the big ones especially near water river basins. And that's where mosquitoes tend to be happiest And again, where there's large populations of dogs and mosquitoes. But they can establish themselves in less desirable areas. If some of these conditions are met, at least part of the year. They're found all over the world, especially the tropics and the warmer climates. But besides the US, they are found in Africa, Europe, Asia, Australia, and New Zealand where they haven't been found is like the colder areas. So like Antarctica, Greenland, yeah. Also, I noticed on the maps I was looking at, Sweden, Norway, and Finland don't have heartworm. Too cold there, I think. In the U. S. they're very strongly established in the southeast. Especially where the Mississippi River basin is. Louisiana, Alabama, Georgia and areas of Texas as well. That's where some of the resistant strains too, which I'll talk about a little bit. There's some resistant, unfortunately heartworms out there and they're coming from that area, the Mississippi River area. But really they're in all the southern states, including Texas and the southern coastlines. The American Heartworm Society has amazing maps and they count every year or two and they put a new map out showing where they are in the country.

Dr. Tyler Sugerman: 17:02

How they've moved.

Dr. Xenia Zawadzkas: 17:03

How they've moved. Yes, that's a big point.

Dr. Tyler Sugerman: 17:07

So do we have it here in the Pacific Northwest?

Dr. Xenia Zawadzkas: 17:09

Yes. So they're not as established here as they are elsewhere, but they are here. They're being documented more all the time. And they've detected the heartworms actually in all 50 states of the U. S. One way or another, they have been documented. Since 2018 the Washington State Department of Agriculture did actually have 418 cases reported just for Washington since 2018. But I think that's underreported because I've actually diagnosed quite a lot of heartworm the past few years.

Dr. Tyler Sugerman: 17:41

Or we've given you quite a lot of heartworm cases. Yes.

Dr. Xenia Zawadzkas: 17:42

And I didn't know that I was supposed to report it, honestly. Like I didn't, I don't think I reported any of those. And I imagine there's a lot of other vets like that too, that just, don't think to do it.

Dr. Tyler Sugerman: 17:51

Exactly.

Dr. Xenia Zawadzkas: 17:52

So I feel like there's probably more than 418 since the last few years. Interestingly, the Washington State Department of Agriculture is considering calling it endemic here now, too, because they've noticed that it's under reported. And that people aren't really following reporting directions.

Dr. Tyler Sugerman: 18:07

Yeah. They're like, oh, I'm supposed to do that?

Dr. Xenia Zawadzkas: 18:10

Testing directions and everything, yeah. But I actually had Jackie pull some reports for our hospital and there was an 18 total count here in the hospital. Nine of these we treated here. Two of them were also, these were ones that I saw, they were positive for microfilaria, which was shocking to me, because that was the first time. here in this very hospital that I saw an infectious dog. And I was like, wow, this dog has baby heartworms. A mosquito is going to bite this dog and then bite another dog and infect that dog with heartworms. So I was at that point like shocked and convinced that it's a problem here too. And that we should, it's an easy way to keep our dogs healthy. Just put them on a preventative. So I'll get into that more. All of these dogs though that we've documented anyway, came from outside the Washington. So most of them were from Texas. I had one from Mexico and there was one from Georgia. So I haven't yet seen any that got it here. Or, were documented you have actually been infected here. It's just a matter of time I think, but I haven't actually seen one. However, I am on a Facebook group for DVM moms, and there's a subgroup for Washington, like just here, and we talk on Facebook occasionally, and I just asked them recently, I'm like, have any of you seen heartworm positive dogs that didn't travel? And a few of them said yes, there was probably four or five that had said, absolute. Yep.

Dr. Tyler Sugerman: 19:34

Yeah.

Dr. Xenia Zawadzkas: 19:34

They were born and raised here. Heartworm positive. Yeah, so that's just another thing that's telling me, oh shoot it's here now. Yeah. And the big problem is just generally though, I think it's happening because there's this huge business to rescue dogs from elsewhere and bring them here. It's very lucrative for these rescue operations. Unfortunately, people have soft hearts and they, you know, they always have pictures of these poor dogs on the street and they're like, will you save this dog? Of course, I'll save it and then it takes a long time to treat a heartworm positive dog and to do it right. And some of these rescue operations just don't have the funding..

Dr. Tyler Sugerman: 20:10

Or if they have a test for it I just found out we had one that came from I think I remember correctly from the Czech Republic to Germany and then Germany to here. It was heartworm positive. And we, I was like it has to be on, it has to have been negative because it travels, right? And they're like no, you don't have to have that to travel here.

Dr. Xenia Zawadzkas: 20:28

Yeah. It's more about rabies. Yeah. But maybe we should also be testing for heartworm. I think a lot of the rescue operations are aware and are doing it, but they're not always fully treating them. And then I think it's hard for the owners too, because it's such a crazy life cycle and it's involved and detailed trying to treat them, they just don't understand the importance of taking them right away to a vet when they get here and test them and be like, okay, is there anything else we need to do? Like some of them, it's like a whole year, Oh, we've been here for 18 months we're from Texas. I'm like, Oh, did you get tested for heartworm? Yeah. Oh yeah. They said they treated. And I'm like let's take a look and see if they're still heartworm positive or not. Cause it's, it takes forever. And a lot of them were actually positive and then we're like shoot, this dog's been here for 18 months and microfilaria positive. And then we're just now getting on treatment. So that's why it's becoming a spreading. This huge movement of dogs and the ignorance around heartworm, I think is a uphill battle.

Dr. Tyler Sugerman: 21:27

Yeah. Which is funny because like in Texas, like they're, they are very used to heartworm. And just don't think about it when you move somewhere else, like to Washington, where it really wasn't endemic before.

Dr. Xenia Zawadzkas: 21:36

Yeah. And a lot of the vets here just. Oh, we don't see it. We don't care about this. And you don't need to worry about heartworm preventative. And then a lot of the times they don't even ask where the dog came from. We don't think to ask the travel history or the owner moved here 3 years ago and they forgot about it, yeah, it's just a lot of that kind of is making it difficult and making it possible for these heartworms to spread here.

Dr. Tyler Sugerman: 21:59

It makes a lot of sense.

Dr. Xenia Zawadzkas: 22:00

Yeah.

Dr. Tyler Sugerman: 22:01

Then how do you test for heartworms then?

Dr. Xenia Zawadzkas: 22:04

Yeah, so blood tests we do. The first one is just a screening heartworm antigen test. It's quick blood draw. It's very specific to female adult worms, especially pregnant ones. It'll come up positive on that test if there's adult female worms. There's also an antibody test, which detects the body's response to heartworms. Not necessarily an active or current infection though. I think this would be more useful for cats if you really wanted to know if they had heartworm because they will produce an antibody to them.

Dr. Tyler Sugerman: 22:33

And if they just have one worm to get like the antigen from that.

Dr. Xenia Zawadzkas: 22:36

They might be negative for the antigen test unless they have an adult worm. And they might not have one at all. Or the one adult that they have could be a male. And then it's just secretly hiding there. So I think antibody is something we'll do more often in a kitty. There is a microfilaria test too that tests for those babies. You basically just look under the microscope. And there's ways to concentrate them. It's called a Knott's test where you look harder for those babies. And you can get different counts of, how many per field there are and see how many are circulating. But basically it's a positive or a negative if they got the babies or not.

Dr. Tyler Sugerman: 23:10

You still send that out?

Dr. Xenia Zawadzkas: 23:12

Yes.

Dr. Tyler Sugerman: 23:12

Do you usually look on the microscope here?

Dr. Xenia Zawadzkas: 23:14

You can. I remembered learning in vet school.

Dr. Tyler Sugerman: 23:17

Yeah. I was like, I did it too.

Dr. Xenia Zawadzkas: 23:18

Yeah. Yeah. I think I did too. It was so long ago though. And honestly, I wouldn't know how to do it now, other than looking at a blood smear and be like,

Dr. Tyler Sugerman: 23:25

So true. I know. I think I did it on this last one. The one that I had that was positive and I was like, I'm not really sure if it was like looking at it. I'm like, I know what it looks like. I've seen one before in school, but

Dr. Xenia Zawadzkas: 23:38

Yeah.

Dr. Tyler Sugerman: 23:38

I didn't see any.

Dr. Xenia Zawadzkas: 23:39

I think it's just like a little tiny worm right next to the red cells. Like you have to not stain it. Maybe you'll see a dead one, but you can see the live ones like on a wet mount. I think that's how they do it at the lab. But I, yeah, I just send those out.

Dr. Tyler Sugerman: 23:53

Yeah, exactly.

Dr. Xenia Zawadzkas: 23:55

Because I would be worried I would miss them. Yeah, so there is one other test too, blood wise occasionally dogs that have had heartworm for a long time, they will produce antibodies to them, and then those antibodies stick to the antigens and hide them from the test. It's called an antigen antibody immune complex. So if you heat the blood sample up, it'll break up that bond of the antibody and antigen and then it'll show up positive.

Dr. Tyler Sugerman: 24:20

Okay.

Dr. Xenia Zawadzkas: 24:21

So we don't have to do that much here because we don't see a ton of heartworm. But like in the south, that's like a big thing that they'll do, especially if they're confused, like they suspect heartworm and it comes up negative. You can do the heat test to just double check.

Dr. Tyler Sugerman: 24:33

So it sounds like if they do come from the south, that's definitely something we should do here though, right?

Dr. Xenia Zawadzkas: 24:37

Maybe if you're suspicious for heartworm and, or like they're positive for microfilaria, but negative for the antigen, like that makes zero sense, right? Like how can they have babies if they don't have adults like giving birth to them? So then they probably have just the complexes that are hiding the antigen. Yeah, there's just a way to double check that if you're suspicious. As far as further testing though, we can also take x-rays and look at the heart. There is, if they have really bad heartworm, they can have physical changes to their heart, like the right side gets really big, full of worms. And then you can see the worms on an echo, on an ultrasound of the heart. The cardiologist can actually look and see adult worms.

Dr. Tyler Sugerman: 25:18

Yeah, they're real creepy.

Dr. Xenia Zawadzkas: 25:19

Have you seen them?

Dr. Tyler Sugerman: 25:20

Yeah. Yeah, in California actually. It was a dog that traveled there. Yeah, we saw the little heartworms in the heart.

Dr. Xenia Zawadzkas: 25:26

Wow.

Dr. Tyler Sugerman: 25:27

Weird.

Dr. Xenia Zawadzkas: 25:27

Yeah. Yeah. So that's, that can be done. Those are all the tests that we have.

Dr. Tyler Sugerman: 25:32

Yeah. So how is heartworm treated then?

Dr. Xenia Zawadzkas: 25:35

It's a lengthy treatment. I always follow the American Heartworm Society protocol. They have one.

Dr. Tyler Sugerman: 25:40

Luckily they have one. Otherwise I think all of us would be like, what do I do?

Dr. Xenia Zawadzkas: 25:44

Yes, I always just, they tell you step by step and it's fantastic. Because it's complicated. I would just refer you there if you ever wanted to know. They do what's called an adulticide treatment. Adult meaning the adult worms and cide is killing. So you kill those adult heartworms in a predictable manner so you can know what to expect. So the goal is to kill the adults in a predictable manner but also kill and prevent all the babies and the larval stages too so that they don't get new adults. So you have to hit all the life cycles, unfortunately. You can't do much for what's happening in the mosquito, but you can try and repel mosquitoes too. That can help, that can be part of the treatment. And you want to do all of this while minimizing the deleterious effects, right? These adult worms are dying. You can imagine if they're a foot long and dying, they're going to let go and start shooting around the dog's lungs and body, and it's just, you can imagine the reactions from that. Yeah, they get lodged in there and clog up things and they can get embolisms from that. So a pulmonary thromboembolism or a PTE, we call it is when like something, it doesn't have to be a worm, it could be a blood clot or whatever blocks up those little arteries in the lungs and then you get an associated inflammatory response and you can sometimes not breathe in that area and it can be fatal. You can die from that and you can have lasting scarring and fibrosis and like changes in your lungs that are chronic and never going to go away. Even after the worms are dead and gone, you can have these chronic lesions in your lungs from it. So you have to try and deal with that and treat that as you go through this treatment. There's also, I have to mention before I go into the treatment protocol, there is a bacteria that lives inside of these heartworms. They're called Wolbachia. And they are pretty fascinating. They are what we call endosymbiotic to the worms, meaning endo is inside so they live inside the heartworms and symbo is like together, and then bio is life. So they're living inside them and helping each other. They both like the Wolbachia obviously needs to live inside the heartworm and then the heartworm does a lot better when they have Wolbachias inside of them. They help them live longer. They help them just be robust and healthy. It's like a probiotic for a heartworm. It's the good bacteria for the heartworm. But so if we kill those Wolbachia, then we are putting a big dent into those heartworms lives, and helping them wither and not live as long. And then also they don't react as much when they die. The dog is more reactive to those Wolbachia when they expose themselves after a heartworm dies and they get a bigger inflammatory response to them. So if the Wolbachia aren't there, the dogs don't react quite as much to the dead worms. Yeah. So really helps prevent the anaphylaxis and allergic reactions that we see if we don't pre treat with the antibiotic first. And that antibiotic is of course doxycycline. Our favorite. Helps with so many parasite problems.

Dr. Tyler Sugerman: 28:59

Exactly.

Dr. Xenia Zawadzkas: 29:00

Yeah. So doxycycline kills the Wolbachia and all of these protocols, they recommend doing a month of doxycycline before you even think about killing the adult worms, and that just helps those heartworms wither and weaken. Their lifespans are shortened and it also prevents the L3s in the mosquito, if a mosquito sucks up microflaria from a dog, and then they change into the L3s inside the mosquito, but then they are just unable to go past that. Like they aren't able to mature into adults eventually. So even though a mosquito might infect an L3 into the dog, or the dog is on doxycycline then those L3s don't turn into the adults. Yeah. Yeah. So it really helps in many areas of the life cycle if we have doxycycline on board. Yeah.

Dr. Tyler Sugerman: 29:47

Is that like because that's where the Wolbachia is getting..

Dr. Xenia Zawadzkas: 29:50

I mean,there must be something about Wolbachia that helps those L3s turn into adults eventually. Yeah, like really helps with their maturation.

Dr. Tyler Sugerman: 30:00

Yeah. Interesting. Okay.

Dr. Xenia Zawadzkas: 30:02

Yeah. That's just when I researched it, it's one of the things that Doxycycline does for us. Yeah. If we get the Wolbachia out of there, that helps. We also want to before we start treatment, we want to look at the dog and see how far along they are with their heartworm, like how many how many worms they have, if we can figure that out, but just like how what the symptoms are for their worm load. So what I've only seen are usually the asymptomatic ones. And I've only again seen five or six cases ever. And so they were maybe had a cough, but maybe it was also just a kennel cough or something not related to their heart worms. But that's what we consider mild symptoms, either no symptoms or just a little bit of a cough. When it becomes moderate, besides a cough, they also have exercise intolerance and abnormal lung sounds. You can hear crackles and wheezes, and they're coughing all the time, and they can't run around very much, they just get tired quickly.

Dr. Tyler Sugerman: 30:55

Okay.

Dr. Xenia Zawadzkas: 30:55

That's called moderate heartworm symptoms. Severe is when they have all the above, plus they just can't breathe very well. You can hear a murmur usually at that point. And they can have fainting spells, where they just don't pump blood well enough and they can just collapse. And they end up usually going into right sided heart failure, because the worms again are on the right side of the heart.

Dr. Tyler Sugerman: 31:16

Yeah.

Dr. Xenia Zawadzkas: 31:17

So when they have right sided heart failure, blood kind of backs up into the right side of the body. And so you can get like a big liver, because the liver is right there, and it will fill up with extra blood. And then because the pressures are so high in those veins, like fluid starts to seep out of those bloods and they can get ascites or fluid building up in their belly and they have these big bellies full of fluid. You can imagine if this goes on, they'll eventually die from the heartworm. But this is really severe and I've never seen one that bad. When you were in California, did you ever see such a bad heartworm?

Dr. Tyler Sugerman: 31:48

Never. Yeah. Like even the one that we had seen, we were doing an echo on. It never got that bad. It was like literally there for a cough. Somebody thought it had heart failure. They sent it to the cardiologist.

Dr. Xenia Zawadzkas: 31:58

Okay.

Dr. Tyler Sugerman: 31:58

And ended up having heartworm.

Dr. Xenia Zawadzkas: 31:59

Oh, interesting.

Dr. Tyler Sugerman: 32:00

So it wasn't even sent there for it.

Dr. Xenia Zawadzkas: 32:02

Okay.

Dr. Tyler Sugerman: 32:02

Because even then, that cardiologist said that she didn't see very many of them in California.

Dr. Xenia Zawadzkas: 32:07

Yeah. Yeah. So I think if you're not practiced at looking for them, you miss them easily.

Dr. Tyler Sugerman: 32:11

Yeah. Yeah. Exactly.

Dr. Xenia Zawadzkas: 32:13

Crazy. But I think like in down south where there's a lot of untreated dogs, Mexico, those sort of places. They probably have dogs like this with severe heartworm disease.

Dr. Tyler Sugerman: 32:21

Exactly.

Dr. Xenia Zawadzkas: 32:22

There is one further step past the severe category called caval syndrome and this is when there's so many worms, like this is the one dog that has hundreds of worms in his heart, they actually start to block the tricuspid valve from actually being able to close at all.

Dr. Tyler Sugerman: 32:38

So that's the first valve between the right atria and right ventricle.

Dr. Xenia Zawadzkas: 32:42

Correct. It's usually closed so that the right ventricle can then pump blood to the lungs. So if that valve can't close, it's like that blood isn't getting into the lungs anymore. Not very well anyway.

Dr. Tyler Sugerman: 32:52

Yeah, it just pushes right back up to the right atria.

Dr. Xenia Zawadzkas: 32:54

Yeah, so it just the heart stops doing its thing. So with the caval syndrome, there's just like a sudden onset of lethargy and they also get hemoglobin building up in their blood, in their urine. I'm not sure why..

Dr. Tyler Sugerman: 33:08

It's'cause all the red blood cells are lysing. So the hemoglobin builds up in there.

Dr. Xenia Zawadzkas: 33:12

That makes sense. Just'cause it's so turbulent inside the..

Dr. Tyler Sugerman: 33:14

Yeah. All the turbulence plus trying to go back to the tricuspid. Trying to go back through all of those worms. It'll just break all the red blood cells down.

Dr. Xenia Zawadzkas: 33:21

Okay. So they get the hemoglobin building up everywhere. And then, the other big symptom for caval syndrome is they'll get pulses visible in their jugular vein. Normally the veins don't have a pulse because the blood's just slowly going back to the heart. And we see pulses in our arteries, because that's where it's being pumped out from the heart. But if we start seeing blood pulses going the wrong way, that's because the blood is not pumping the right way anymore. And so that's like the key symptom with caval syndrome is they'll get the jugular pulses. And then usually if that goes untreated and you don't take those worms out surgically, and they will die within two days, if not sooner, once you start seeing that. So super severe. And yes, it can kill a dog.

Dr. Tyler Sugerman: 34:02

Yeah. Yeah.

Dr. Xenia Zawadzkas: 34:03

It takes a long time, I think, to get to that point, but that's certainly the end stage heartworm disease. Unfortunately.

Dr. Tyler Sugerman: 34:10

It's terrible.

Dr. Xenia Zawadzkas: 34:10

I've never seen that either, but I've heard about it.

Dr. Tyler Sugerman: 34:12

Yeah, I've seen videos of it like I'm removing it from the vene cava.

Dr. Xenia Zawadzkas: 34:17

Yeah, so I've never referred anybody for that kind of a treatment but that's another way to treat is to, you know have a specialist go in. I think they go in through the veins right and

Dr. Tyler Sugerman: 34:30

To the jugular vein.

Dr. Xenia Zawadzkas: 34:30

Yeah. And then into the heart through there. And physically pull out adult heartworms. Like in bunches.

Dr. Tyler Sugerman: 34:38

Yeah.

Dr. Xenia Zawadzkas: 34:38

I've seen videos of it.

Dr. Tyler Sugerman: 34:39

It's so crazy.

Dr. Xenia Zawadzkas: 34:39

Yeah. I doubt they could get all of them but they'd probably get a lot of them so that the valve can actually close again. Yeah. And we can save them that way. Yeah. So let's go into now that we know that background let's go into the actual American Heartworm Society treatment protocol. It's about a year long protocol and they have it, they go month by month on it. So the 1st step is to confirm that the dog's positive. So say we're just screening and the antigen surprise comes up positive. You want to test again to make sure before we go through all of this. So you test one more time, and on that second test, you should do a microfilaria test as well if you haven't already, just to see are they infectious or not, and do we need to deal with those microfilaria first or not. And then they also recommend at that point putting a mosquito repellent on, which is new, and since I just went through this again, they didn't say that before, but they're saying that now. It totally makes sense, right? You want to try and keep the mosquito bites down. While you're treating all this. There's a few different just over the counter flea medicines that also cover mosquitoes. So these would be like Frontline or Advantage or Vectra, which we have in the hospital. They're actually pretty good at repelling mosquitoes. So I would double up on that. Double up with your heartworm preventative plus add on a topical mosquito repellent at this point. Yeah. And then, at this point, you're going to also determine the severity of the disease, are we mild, moderate, severe, or caval syndrome?

Dr. Tyler Sugerman: 36:03

Yeah, or terrible.

Dr. Xenia Zawadzkas: 36:05

And yeah, slash terrible, yes. Again, all the ones I've seen have always been mild, so I didn't have to do a whole lot more at that point. But, assuming they are, like, in heart failure or something, you've got to take measures to try and stabilize that. Heart medications, diuretics, whatever it takes to get their heart working better as it can. And then you want to start your doxycycline like right away. Basically day one you're gonna start your doxycycline for four weeks course is recommended to help those Wolbachia die and it starts those worms to withering and all of that. If they have symptoms like they're coughing or if they're positive for microfilaria, you want to start steroids at this point too. It'll help with reactions to dying baby heartworms and help with the coughing and the inflammation in the lungs. So you do doxycycline and prednisone usually right in the beginning. Also it says if they have microfilaria, you could do some Benadryl as well. Just get them on Benadryl too. Why not? Yeah. And then you give your first heartworm preventative, and I always use Simparica Trio, but there's a bunch of them out there, and I will go through those later. And then at this point, you're going to start exercise restriction, which is one of the hardest things with these heartworm treatments. You can imagine if the dog's running around and his heart's beating really fast, and we start having baby worms dying and everything, they're just shooting around even faster. And more likely to have anaphylaxis problems and pulmonary thromboembolisms and all of that. So you have to, through all of this, restrict their activity. You don't have to be super strict at this point, but you're going to start thinking about it, and you're not going to go on runs and play with your dog and have them fetch the ball and stuff. You have to just walk and yeah, walk everywhere. Yeah. Okay. Then on day 30, so a month after starting all that you give your second monthly preventative. So another dose of Simparica Trio. And they say here you put on another mosquito repellent. So another dose of Frontline.

Dr. Tyler Sugerman: 37:58

Okay.

Dr. Xenia Zawadzkas: 37:58

And then you're just gonna wait the next month. Don't do anything after that because if you give a month after the doxycycline finishes then for sure all those Wolbachia bacteria are gonna die and it just helps in the studies that they've done over time there's a lot less reactions to everything if you just give a good month after the doxycycline to just help those worms wither. Okay, then on day 61 you give another dose of Simparica Trio. Because we're on the third month now and then you do your first big adulticide treatment. And this is the only way to kill those adult worms is basically a big arsenic shot. It's a poison. It's called melarsomine, but it's like similar to arsenic.

Dr. Tyler Sugerman: 38:38

Right.

Dr. Xenia Zawadzkas: 38:38

And we have to do a big shot in the muscles in the back. And it seems like best tolerated by the dogs in that spot. That's still very painful. Some dogs, I've been able to do awake. Other ones are crazy and moving. And I've actually just sedated them so that they're quiet while I give the giant shot.

Dr. Tyler Sugerman: 38:54

Not so painful.

Dr. Xenia Zawadzkas: 38:55

Yeah, it's not a giant shot. It's usually a mL or two, but it's just creepy. I'm always like shaking when I'm doing it. I don't like it. And I've noticed on some of the first ones I treated they were like Nicole's dog, actually. He was positive. And so he was very drooly and like shifting after I gave it and like nauseous. And so I started treating him on the future shots with Cerenia and Gabapentin and it totally changed and made it all much better. So now I just do that for all of them. They get Cerenia and they get Gabapentin. So Cerenia, for those that don't know, treats nausea, makes them less nauseous. And then Gabapentin is a nice painkiller. It's also sedating, which is nice because we want them to be real quiet when we're doing all of this. I might just give a few weeks of gabapentin. You can just keep using it if you need it. At this point also, when you start the melarsomine shots, you want to do pred again. So another whole tapering course of it to help prevent reactions to the dying worms. And then this is where you start your strict exercise restriction. So you basically have them in a crate all day. And you take them out on a leash. Don't let them run out in the backyard to poop and pee. You go out there on a leash, poop and pee, come back and get in the crate. So you basically have to be quiet for a good couple of months at this point. You know, cage restriction unfortunately. The American Heartworm Society has some really nice links and tips to keeping your dog entertained while they're caged, just food puzzles and, toys and stuff that they can chew on in the crate, to keep their mind from going bonkers. Yeah, and we can certainly help with drugs like Gabapentin and Trazodone and just keeping them sleepy most of the time. It'll help them get through this without trouble.

Dr. Tyler Sugerman: 40:35

Yeah.

Dr. Xenia Zawadzkas: 40:36

Also, prednisone causes weight gain and it has side effects, they drink a lot, they pee a lot, and then they're not moving, and so you can expect some weight gain at this point, which is like almost impossible to prevent. Although I did have one pug owner that her little positive pug, she was really good about restricting food and he didn't, I'm sure she was miserable. But she didn't gain weight. She stayed steady. I was very proud of those owners.

Dr. Tyler Sugerman: 41:01

Nice. Especially for a pug.

Dr. Xenia Zawadzkas: 41:02

Yeah, I know. Must've been awful at home, but.. Yeah, the inactivity and the pred, it's usually, it's not fun but you got to do it, you got to crate them.

Dr. Tyler Sugerman: 41:13

Yeah.

Dr. Xenia Zawadzkas: 41:13

Day 90 another dose of Simparica Trio, and then we give the second melarsomine injection. We give another course of pred, if we tapered it off, we have to restart it again the next month. And then day 91, so the very next day, we do the third and final melarsomine shot.

Dr. Tyler Sugerman: 41:29

Oh wow, that's real fast.

Dr. Xenia Zawadzkas: 41:30

Yeah. So basically there's three melarsomine shots, to recap. You give one, and then you wait a month, and then you give two more a day apart.

Dr. Tyler Sugerman: 41:38

Okay.

Dr. Xenia Zawadzkas: 41:39

So there's three total. And then after that third melarsomine shot, so day 91, you have to continue the strict exercise restriction for another six to eight weeks following the last injection. So basically those first three, four months, you're keeping your dog super quiet.

Dr. Tyler Sugerman: 41:56

Yeah.

Dr. Xenia Zawadzkas: 41:57

Yep. And then you just keep going after that with the monthly preventative. So keep going every month, Simparica Trio afterwards, you can let the pred wear off at that point. And hopefully the weight gain isn't so bad after that.

Dr. Tyler Sugerman: 42:11

Hopefully.

Dr. Xenia Zawadzkas: 42:11

Yeah. And then on day 120, it says to test for microfilaria. You just want to see, have we cleared microfilaria or not. The two positive dogs that I had that were positive for microfilaria, they were negative at that point. So I was like, Simparica Trio works. We're no longer infectious. And then after that you just wait till the year mark. So this would be about nine months after the final melarsomine shot. If you test before then, you're probably still going to be antigen positive because, again, it's just detecting those adult heartworms. They're probably not completely dissolved and absorbed by the dog at that point. Even though they're dead, they're probably still there and hanging out in the lungs in bits. And coming up positive on the test. So they say after the nine month mark, though, if you killed them all, they should be negative at that point for the antigen test. And the few that I've done were negative at the year mark. Thank goodness. So I did see it all work.

Dr. Tyler Sugerman: 43:08

Yeah, this does work.

Dr. Xenia Zawadzkas: 43:10

Yeah. If they're still positive though, then there's directions on the American Heartworm Society. You're supposed to retreat with another month of doxycycline and then do two more melarsomine shots 24 hours apart. So basically you repeat it all and keep testing. And I would say. I'm wondering why, what the scenario would be, why they would still be positive. I guess the melarsomine just failed and didn't kill all of them. Yeah. Or they got infected again.

Dr. Tyler Sugerman: 43:38

Yeah, I was gonna say, maybe they just got infected again. Especially in that one month when they're not on anything.

Dr. Xenia Zawadzkas: 43:42

Yeah. If they didn't give the Simparica Trio every month, they could have a window where another mosquito bit them. Yep.

Dr. Tyler Sugerman: 43:49

Then so there's been a slow kill method now that I've heard talked about. Can you tell me about that?

Dr. Xenia Zawadzkas: 43:55

So yeah, the slow kill method doesn't involve the melarsomine injections because it's horrible to go through that. And then a lot of people just don't want to do that to their dog. And a lot of the shelters, not a lot, but there's been a couple of the rescue operations, they're like, Oh, we just do the slow kill here. And that's what we're giving your dog as we ship it to you in Washington. But it's a misnomer cause you're not actually killing the adult worms at all. So the preventatives, like ivermectin.. I'll just go into it. So there's the macrocyclic lactones are all the options for heartworm prevention. Those include ivermectin, selamectin, milbemycin oxime, and then moxidectin. So those are the four options. The brand names for those, like the ivermectin is in Heartgard Plus, or Iverhart, there's a lot of them out there, and then selamectin is in Revolution, that's the topical prescription one, and then we have milbemycin oxime, which is in Interceptor and Sentinel, I believe, and Trifexis has milbemycin. And then there's Nexgard Spectra, which I don't think they make anymore. That had milbemycin oxime in it, but now they have Nexgard Plus, which has the moxidectin in it. And so does Simparica Trio. Simparica Trio has moxidectin. And I think of all of them, moxidectin is the best from what I can gather. But I wanted to point out moxidectin is the one that does actually get the resistant strains of heartworm that are emerging from like the Mississippi river basin. That's where these resistant heartworm worms are. That's where they're showing up. And so the milbemycin, and selenamtin, and ivermectin, the older heartworm preventatives, they don't touch those resistant heartworms at all. They just don't work at all.

Dr. Tyler Sugerman: 45:33

So would it be fair to say you could use one of those other ones first, and if that doesn't work, then you have to go to the..

Dr. Xenia Zawadzkas: 45:41

Moxiedectin. Yeah, I mean you can. They're still available and they still work great on most of the other heartworms. Yeah, there's a very small amount of these resistant ones they don't seem to be thankfully that prevalent. Yeah, so I think any heartworm preventative is better than none but it seems like the moxidectin works the best against these resistant ones, so maybe those are the ones we really should be using, just so we don't have to worry about resistance strains.

Dr. Tyler Sugerman: 46:08

Great.

Dr. Xenia Zawadzkas: 46:09

Simparica Trio has moxidectin. Advantage Multi has a topical with moxidectin in it, those work for resistance strains too. And then the ProHeart injections that's really a high dose of moxidectin is in that one.

Dr. Tyler Sugerman: 46:23

Okay,

Dr. Xenia Zawadzkas: 46:24

So yeah I just wanted to make sure I mentioned that's what covers the resistance

Dr. Tyler Sugerman: 46:29

I think it's the newest one as well, if I remember correctly.

Dr. Xenia Zawadzkas: 46:32

It's actually an old medication. It's been around a long time. It's also in Advantage Multi, which is a topical medication. And it's, yeah, it's been labeled for many different dewormer treatment. But yeah, so those slow kill methods use just a preventative with one of those medications in it and they just give it every month. And they say, okay, eventually the adults will die on their own. And then we're just..

Dr. Tyler Sugerman: 46:55

Five to seven years.

Dr. Xenia Zawadzkas: 46:56

Exactly. So for five to seven years these dogs still have adult heartworms, and so yeah, maybe you're killing their babies slowly and preventing any new ones from becoming additional adult heartworms but they're not killing the adults at all.

Dr. Tyler Sugerman: 47:10

Or the Wolbachia.

Dr. Xenia Zawadzkas: 47:12

Yeah. But there is another slow kill method that follows that they call it the Mox-Dox slow kill method.

Dr. Tyler Sugerman: 47:18

Okay.

Dr. Xenia Zawadzkas: 47:19

So they use moxidectin, either in Advantage Multi or Simparica Trio or Nexgard Plus and they give doxycycline as well for a month. And then so then the Wolbachia are withering the adults and maybe they don't live as long. So maybe two to three years if we're lucky instead of five to seven. But still it doesn't kill those adults. So they're still dealing with those. Also, I think moxidectin at higher doses has been shown to kill some of the adult worms or maybe they die a little bit more quickly. Again, because their lifespan is shorter, but we just don't know when they're going to die. And so that's another risk for these types of protocols. Cause at least with the American Heartworm Society, when we know when they're dying, we know when we have to exercise restrict them during this eight week period, they have to be cage rested. If you're doing slow kill, they could just randomly have an adult die whenever. And then they're like, boom, running around one day and they die from anaphylaxis, so it's less predictable. And less safe, in my opinion. And it's not recommended by the American Heartworm Society. It's only, they advise against it unless it's like a salvage procedure, which, when they just can't even consider adulticide treatment at all for whatever reason.

Dr. Tyler Sugerman: 48:31

Costs maybe..

Dr. Xenia Zawadzkas: 48:32

Maybe. It's not that bad. I want to say it's a few hundred dollars to buy the melarsomine.

Dr. Tyler Sugerman: 48:38

Yeah.

Dr. Xenia Zawadzkas: 48:39

And then there's like the rechecks and stuff, but it's, I don't know, it's not an extremely expensive treatment.

Dr. Tyler Sugerman: 48:43

Yeah.

Dr. Xenia Zawadzkas: 48:44

So I really see no reason to do the slow kill method. You can imagine physically worms in the heart are just constantly banging around in there as the heart's beating and causing damage to the heart and the lungs chronically.

Dr. Tyler Sugerman: 48:56

Yeah.

Dr. Xenia Zawadzkas: 48:57

It's good to get them out as soon as possible.

Dr. Tyler Sugerman: 48:59

As soon as possible. About 5 to 7 years.

Dr. Xenia Zawadzkas: 49:01

Yeah.

Dr. Tyler Sugerman: 49:01

Yeah.

Dr. Xenia Zawadzkas: 49:02

Yeah. So I don't recommend the slow kill method.

Dr. Tyler Sugerman: 49:04

Okay. So then can you recap from like how you prevent heartworm and so that we don't have to go through this right? So we don't ever have to go through the melarsomine injections.

Dr. Xenia Zawadzkas: 49:14

Yeah, that's the idea. It's not have to end up doing any of that. So back to the macrocytic lactones, those are our big choices for prevention. And what they do is kill the, basically all of them kill the L3s and the L4s.

Dr. Tyler Sugerman: 49:28

So before the adult.. Right before then.

Dr. Xenia Zawadzkas: 49:30

So they get bit by a mosquito that has an L3 and those L3s are then capable of turning into adults into the heart of the dog. So if we give them a monthly preventative, they're killing the L3s and the L4s before they become adults. Some of them will kill the microfilaria too, but they do it with different degrees of effectiveness, I should say. A lot of them are combo products too. Like they're just trying to make it easy because there's more than heartworm that we need to worry about, right? Fleas and ticks like we talked about before and they bring their own problems. And so they've just basically added heartworm preventatives to those other kind of treatments. Besides the orals that I already mentioned. There is an injection called ProHeart. ProHeart is just straight moxidectin. And it's a very slow release formula. So you give it a shot under the skin, and it just over six months slowly dissipates and kills baby heartworms and L3s and L4s. There's also a 12 month one, which is crazy, but it lasts for a whole year, so there's a 6 month and a 12 month now. Yeah, Zoetis came out with it, we don't have that here because we just don't see a lot of heartworm, but it's a big product in the South for vet clinics. So you could just do that and just take care of heartworm with that, but here we see so many other parasites too that we just added it to the oral combo products and there's always better ones coming out. Who knows what I'll be recommending five years from now?

Dr. Tyler Sugerman: 50:58

Or even a year from now.

Dr. Xenia Zawadzkas: 50:59

I know, yeah, it's crazy. And then adding in the mosquito repellents seems to be helpful too, especially in the beginning, or if you're in an area with a ton of mosquitoes, you should probably be doing that on top of the heartworm preventative.

Dr. Tyler Sugerman: 51:11

Right, and that was the Advantage and the Frontline you were talking about.

Dr. Xenia Zawadzkas: 51:14

And Vectra, yeah. You don't want to put DEET on your dog like the stuff that we use when we're hiking.

Dr. Tyler Sugerman: 51:21

Yeah

Dr. Xenia Zawadzkas: 51:22

It's just a little more toxic to dogs and cats, but also they are more likely to lick themselves like humans don't usually go around licking our arms after we spray DEET on there. But dogs and cats will often lick and ingest some of that DEET and then it's really bad. Yeah, they have all kinds of neurologic.. I'm sure you've talked about it or seen it.

Dr. Tyler Sugerman: 51:40

I've seen one before. I haven't talked about it yet, but I've definitely seen one.

Dr. Xenia Zawadzkas: 51:43

Yeah, so it's not good. I don't recommend the DEET products at all. But the ones that are labeled for dogs and cats Advantage, Frontline, and Vectra can be repellent as well. And also I mentioned I don't know if you remember in the flea one and the tick one, the isoxazolines do actually kill mosquitoes too. They kill lots of insects, but.. So after the mosquito bites it will die, which is nice. So it won't go on to infect another dog with, yeah, heartworm.

Dr. Tyler Sugerman: 52:08

Yeah.

Dr. Xenia Zawadzkas: 52:08

But it doesn't prevent it from biting though. So if you want to have some repellent activity, you can double up with one of those topicals. Yeah. Seresto collars too will repel. Yeah. They have the flumethrin, I think, in their collars. Yeah. Which helps they don't like the smell of it. And they don't land on the dog. Yeah.

Dr. Tyler Sugerman: 52:25

Nice. And so I remember learning that all dogs should be tested before we give heartworm prevention. Because apparently we could kill the dogs right if we just go ahead and give it. So is that true?

Dr. Xenia Zawadzkas: 52:35

Actually it's not true. It's always a concern, right? If you have a high burden of microfilaria, baby heartworms, circulating and then you start killing them. Yeah, there's a chance the dog's gonna have some allergic reactions to all of those baby dying heartworms. However, it's not as bad as you think.. You don't need to bother testing puppies that are less than six months old. Because there simply is no way that an adult worm can develop that quickly. It takes about at least six months for a teenager heartworm to turn into an adult heartworm and get in the heart. And the tests that we have unfortunately only test for the heart adults. Like you don't, you can't test for the teenage. Like L3s and L4s, yeah, you can only detect the adults once they're there. So there's really no reason to test a puppy less than six months before starting a heartworm preventative. Just go ahead and start those young puppies on a preventative and it'll kill any teenager heartworms that, you know, even if they were bit by a mosquito when they were first born and given some teenager heartworms, those aren't going to get into their heart for six months. Yeah, just go ahead and start those puppies on the preventatives. They've done some pretty amazing studies. Like giving dogs heartworms. I don't know how they do it.

Dr. Tyler Sugerman: 53:49

Infecting them?

Dr. Xenia Zawadzkas: 53:50

They implanted, and I was reading the study, 24 dogs were implanted with adult heartworms. 10 females and 10 males.

Dr. Tyler Sugerman: 53:58

That's so weird.

Dr. Xenia Zawadzkas: 53:59

I wonder, like, how they actually do it. Like, where do they get these adult heartworms? And then how do they like, they go in the vein?

Dr. Tyler Sugerman: 54:05

Do they do it with a jugular again? Just, I don't know.

Dr. Xenia Zawadzkas: 54:07

Crazy.

Dr. Tyler Sugerman: 54:07

That's weird.

Dr. Xenia Zawadzkas: 54:08

But they do it. And then they wait for those adults to set up house and start making babies. And then they documented they were all microflaria positive. And then they gave them, I think the specific study I'm thinking of was on Simparica Trio, and they gave them one dose and three times the dose. And without any pred or benadryl or anything. And they all were fine. A couple of them, I think two out of the 24 dogs had transient fevers and that was it. Like a day of a fever and they were fine. But there was no anaphylaxis or anything else. So after reading that, I'm like a lot more comfortable with, oh, it doesn't really matter if you're positive, you're going to, we're not going to hurt you, but that said, it's always a good idea to test first, right? It's always, and it is recommended by the American Heartworm Society. Like we should be checking every year, pretty much all dogs for heartworm, especially before putting them on a preventative. Not just to make sure they're not positive for microfilaria, but also to start documenting and not missing so many cases because we're starting to see more and more. So I feel like, yeah, we should be screening for it more in general.

Dr. Tyler Sugerman: 55:09

And if we don't, we're essentially just doing the slow kill method again and not actually treating them because we don't know that they're positive.

Dr. Xenia Zawadzkas: 55:15

And that's why I think these rescues think, oh, it's fine we're just giving them the Simparica Trio or Heartgard every month and eventually their heartworms will die and we're not going to hurt the dog with it. So yeah, the test is not imperative to do before you start treating. And again since we don't see it a lot I don't really harp on it as much as I probably should and I have enough to talk about during the appointment but the only product I think that they insist on the label testing first is the ProHeart 6 and 12 because it's a really high dose of moxidectin and I think you're probably going to kill the babies off really quick.

Dr. Tyler Sugerman: 55:52

Yeah, that makes sense.

Dr. Xenia Zawadzkas: 55:53

Yeah. And moxidectin is one of those drugs. Like the more you give it, like the longer repeating courses of it, the higher effectiveness it is. So like it won't kill all the baby heartworms right away. It takes a few months for them all to die. And that's why on the protocol, they recommend not testing for microfilaria until day 120 because by then enough, like three or four months of the Simparica Trio should have killed all the baby heartworms by then.

Dr. Tyler Sugerman: 56:16

Right.

Dr. Xenia Zawadzkas: 56:17

Yeah, but it might still be positive a month or two before that. Yeah, so..

Dr. Tyler Sugerman: 56:20

That's really good to know we actually had a patient who we weren't sure their symptoms that.. They were like anaphylactic symptoms were from them starting heartworm prevention when we knew now that the dog was heartworm positive. So..

Dr. Xenia Zawadzkas: 56:32

Yeah.

Dr. Tyler Sugerman: 56:33

It's good to know.

Dr. Xenia Zawadzkas: 56:33

Yeah, it's okay to go ahead and just start it.

Dr. Tyler Sugerman: 56:35

Yeah, okay. And then so is there any over the counter heartworm preventions that we can use?

Dr. Xenia Zawadzkas: 56:40

No. Simply.

Dr. Tyler Sugerman: 56:41

Yeah.

Dr. Xenia Zawadzkas: 56:41

Nope.

Dr. Tyler Sugerman: 56:43

Just mosquito repellent.

Dr. Xenia Zawadzkas: 56:44

Yeah. Yes. Yeah, you can repel the mosquitoes with over the counter products, but you can't kill baby heartworms or adult heartworms with over the counter meds. Nothing works.

Dr. Tyler Sugerman: 56:53

Yeah. All pretty much veterinary drugs.

Dr. Xenia Zawadzkas: 56:56

Yep. And it's important to have a vet help you through it, too, because it's such a tricky thing and you've got to do it carefully and keep checking and monitoring to see how we're doing.

Dr. Tyler Sugerman: 57:05

Yeah. And also to give as little drugs as possible, so that way you're giving other drugs for fleas and ticks and..

Dr. Xenia Zawadzkas: 57:10

Yeah.

Dr. Tyler Sugerman: 57:11

Yep.

Dr. Xenia Zawadzkas: 57:11

Yeah. There's so many parasites. That's why I really like Simparica Trio just because it makes it so easy. You just do everything in one. And the owner doesn't have to think twice about it.

Dr. Tyler Sugerman: 57:22

Exactly.

Dr. Xenia Zawadzkas: 57:22

Yeah. One thing I'll mention about Nexgard Plus, because that also has moxidectin in it and I think it would be another good option. But the moxidectin dose is a lot lower than Simparica Trio, and so it's actually not as certain that it'll kill the babies or microfilaria. I prefer the Simparica Trio because it's got a higher dose of moxidectin.

Dr. Tyler Sugerman: 57:43

Yeah, nice.

Dr. Xenia Zawadzkas: 57:45

As far as sources go, I encourage everybody listening to just check out the American Heartworm Society website. It's amazing. They have all kinds of resources. They go over the life cycle in detail and they have client handouts and like easy to read things that kind of show you why we recommend this and that, and busting myths and that kind of thing.

Dr. Tyler Sugerman: 58:02

Yeah.

Dr. Xenia Zawadzkas: 58:03

And then, yeah, I looked at good old Wikipedia and

Dr. Tyler Sugerman: 58:07

I saw that.

Dr. Xenia Zawadzkas: 58:08

Yep. There's some great info there. And VeterinaryPartner.com is a good resource.

Dr. Tyler Sugerman: 58:13

I love that.

Dr. Xenia Zawadzkas: 58:13

Like for any kind of vet questions. Yeah.

Dr. Tyler Sugerman: 58:15

I will say when you do veterinary partner, you do have to make sure that you've spelled whatever it is correctly.

Dr. Xenia Zawadzkas: 58:20

Okay.

Dr. Tyler Sugerman: 58:20

Like If you accidentally misspell heartworm. It's spelled H A instead of H E A. It will not pop up.

Dr. Xenia Zawadzkas: 58:26

Interesting.

Dr. Tyler Sugerman: 58:26

Yeah. You do have to actually spell it correctly for things to pop up.

Dr. Xenia Zawadzkas: 58:29

That's good to know. Didn't know that. Yeah. And then the American Animal Hospital Association, AAHA. They had a lot of good info on heartworm as well. And when I was trying to figure out like the history of heartworm, I actually ended up at the Encyclopedia of Arkansas.

Dr. Tyler Sugerman: 58:44

Of Arkansas.

Dr. Xenia Zawadzkas: 58:44

Yeah, that's where I found like the years that the monster heartworm was found. And then there is one good article about the safety of moxidectin for microflaria positive dogs that I actually sourced there for anybody if they want to read the whole study.

Dr. Tyler Sugerman: 58:59

Yeah, absolutely. And we'll post that on there in our links as well too.

Dr. Xenia Zawadzkas: 59:02

Good, good.

Dr. Tyler Sugerman: 59:03

Perfect. Was there anything else that you wanted to add to this?

Dr. Xenia Zawadzkas: 59:06

No, you always ask me a question.

Dr. Tyler Sugerman: 59:08

I do always ask you a question. So my question today is actually going to be like, how did you get into parasites in general? What is it about parasites that, that you love so much?

Dr. Xenia Zawadzkas: 59:19

I don't know. I don't have a good answer. I'm trying to think. Like I..

Dr. Tyler Sugerman: 59:24

I thought you were going to say it because you can prevent them, because you can treat them.

Dr. Xenia Zawadzkas: 59:28

Of course. I was trying to imagine the, like a, something that happened to me and made me hate parasites and want to kill them all. And I can't think of any one thing, except like I really hate mosquito bites. And I hate flea bites too. I've been bit by fleas and I think I'm allergic to them because I get like a welt the size of a quarter. And it's 20 times as itchy as a mosquito bite. And I'm miserable.

Dr. Tyler Sugerman: 59:51

Yeah.

Dr. Xenia Zawadzkas: 59:51

Yeah. And they're there for a week before they finally go. It's just, so I really hate fleas like with a passion.

Dr. Tyler Sugerman: 1:00:00

That makes sense. Yeah.

Dr. Xenia Zawadzkas: 1:00:01

Yeah. Can I ask you a question?

Dr. Tyler Sugerman: 1:00:03

Oh yeah, sure.

Dr. Xenia Zawadzkas: 1:00:05

What is your favorite color?

Dr. Tyler Sugerman: 1:00:08

So my favorite color is blue. It always has been blue. Like even since I was little, yeah. I even had a little blue parakeets. I had.. I don't know, like six of them because they kept dying, but all six of them are named baby blue, which is baby blue one, two, three, four, five, and six.

Dr. Xenia Zawadzkas: 1:00:23

That's hilarious.

Dr. Tyler Sugerman: 1:00:27

Yeah, I know it's a really common color for all boys to like, but yeah, definitely blue is my favorite color.

Dr. Xenia Zawadzkas: 1:00:31

That's funny. Mine's green. I just like greens. Peaceful, calming.

Dr. Tyler Sugerman: 1:00:35

Yeah. I think it's actually too because my, so I have the same eyes as my grandpa and he had very blue eyes that turned like grayish eyes. And so I always remember like his very blue eyes.

Dr. Xenia Zawadzkas: 1:00:44

Oh, that's super nice.

Dr. Tyler Sugerman: 1:00:45

Yeah.

Dr. Xenia Zawadzkas: 1:00:46

You have blue eyes too, I just noticed.

Dr. Tyler Sugerman: 1:00:47

I do have blue eyes, yes. They did start to turn gray, just like his, but yeah, they were like a very bright blue when I was little.

Dr. Xenia Zawadzkas: 1:00:53

Super nice.

Dr. Tyler Sugerman: 1:00:54

Yeah.

Dr. Xenia Zawadzkas: 1:00:54

Blue's a good color.

Dr. Tyler Sugerman: 1:00:55

Yeah. Thanks for asking me a question.

Dr. Xenia Zawadzkas: 1:00:57

Oh, yeah. I was like, I should ask him a question. I love it. Keep it simple. Yeah.

Dr. Tyler Sugerman: 1:01:01

Nobody ever asked me a question.

Dr. Xenia Zawadzkas: 1:01:04

I'll have to think of a better one next time.

Dr. Tyler Sugerman: 1:01:07

All right. Perfect. Thank you, Dr. Z I appreciate this so much coming on to talk about heartworm. I know how much work you put into this.

Dr. Xenia Zawadzkas: 1:01:12

Oh, thanks.

Dr. Tyler Sugerman: 1:01:12

To like come up with this today. So I really do appreciate that'cause it's gonna help us, especially like us in the clinic since we don't know a lot about it too. A lot of times we just send it over to you,

Dr. Xenia Zawadzkas: 1:01:22

Yeah. Which I'm happy to take it, but I think it helps if everybody knows about it.

Dr. Tyler Sugerman: 1:01:26

Exactly.

Dr. Xenia Zawadzkas: 1:01:26

And is aware of the increasing numbers. That this is something we should start really, helping dogs with and preventing.

Dr. Tyler Sugerman: 1:01:34

And also just to know what we should start with to give doxycycline and prednisone before we have an appointment with you.

Dr. Xenia Zawadzkas: 1:01:40

Yes, and the other big point I'll make, if you get a positive on a screen test, send it out again and do the microfilaria test too. Do both. And then start your doxycycline and then send it over to me.

Dr. Tyler Sugerman: 1:01:49

Perfect. Alright, thank you again, and thank you to everybody listening. As always, make sure to keep your pets happy, healthy, and safe. Thank you guys. Bye. I just want to say thank you again to Dr. Z for all of this really important information that she has given to us about heartworm disease and heartworm prevention. Our goal is to really help people to be able to save your pet's life. Also, thank you to Sumner Vet Hospital for allowing us the space to be able to record, to Shawn Hyberg for doing our editing, and for Kelly Dwyer for doing our website. In the next coming weeks, we're going to be hearing from the ophthalmologist to learn more about how an ophthalmologist helps our pets. We'll see you next week.